MVN User Manual User Guide MVN, MVN BIOMECH MVN Link, MVN Awinda Document MV0319P, Revision N, June 2015
Revisions Revision Date By Changes N June 2015 HBE Changes made to accommodate MVN Studio 4.2 9.3 Add comments after recording 15.3 Software Activation Tool: Offline License Activation or Updating a License 15.4 Software Activation Tool: Applying an Update 15.5 RUS Utility: Rehosting a Sentinel protection key © 2015, Xsens. All rights reserved. Information in this document is subject to change without notice.
Table of Contents REVISIONS ................................................................................................................................................. II TABLE OF CONTENTS................................................................................................................................. III ABBREVIATIONS AND TERMS .................................................................................................................... IX DEFAULT FOLDERS ........................
5.4 SYNC STATION ................................................................................................................................ 14 5.5 BATTERY CHARGER .......................................................................................................................... 15 5.5.1 Using your Charger ............................................................................................................. 15 5.5.2 Charging ................................................................
7.2.10 System Status..................................................................................................................... 33 7.2.11 Suit Configuration............................................................................................................... 33 7.2.12 Scenario............................................................................................................................. 34 7.2.13 Accept Systems .................................................................
10.3.1 Selection of samples ........................................................................................................... 63 10.3.2 Contact point editing options .............................................................................................. 64 10.4 REPROCESSING ............................................................................................................................... 66 10.5 MULTI-PERSON EDITING ...............................................................
15.3 SOFTWARE ACTIVATION TOOL: OFFLINE LICENSE ACTIVATION OR UPDATING A LICENSE ........................................ 91 15.3.1 Step 1: Retrieve the license information from a Sentinel protection key ................................... 91 15.3.2 Step 2: Send the C2V file...................................................................................................... 91 15.3.3 Step 3: Apply the received v2c file using the Software Activation tool...................................... 91 15.
19.8.1 Euler Extractions for the joint angles .................................................................................. 120 19.8.2 Shoulder angle definitions ................................................................................................. 120 19.8.3 Joint angle outputs ........................................................................................................... 121 19.9 XKF-HM ............................................................................................
Abbreviations and Terms API Application Programming Interface AP Access Point: The method of transporting data from the body pack to the PC BP Body Pack, on-body controller unit for the motion trackers, connects to power and wireless transmission of data to host PC via the Access Point .BVH Biovision Hierarchy character animation file format .C3D Coordinate 3D export format Character Subject in 3D view .
Default Folders Description Files Location Main program MVN Studio.exe C:\Program Files\Xsens\MVN Studio \MVN Studio Documentation MVN Quick Setup Sheet.pdf C:\Program Files\Xsens\MVN Studio \Documentation Document MV0319P.N x © Xsens Technologies B.V.
1 Introduction The Xsens MVN inertial motion capture system is an easy to use, cost efficient system for full-body human motion capture. MVN is based on Xsens' state-of-the-art miniature inertial sensors and wireless communication solutions combined with advanced sensor fusion algorithms, using assumptions of biomechanical models. MVN is a completely portable system; it is not restricted to a studio or lab. It can be used anywhere: outside, in the office, and on the work floor.
2 Content overview 2.1 MVN Link suitcase with contents Figure 1: Suitcase containing the MVN Link System 2.2 The MVN Link System arrives in a strong, durable and watertight case. The case has wheels and an extendable handle for easy transportation. The suitcase dimensions meet the requirements for most airline hand-luggage.
2.3 Body Pack (BP), Battery Pack, and Access Point (AP) Figure 5: Access Point (AP) Figure 4: Body Pack (BP) Figure 5 shows the Access Point. The Access Point pairs with the Body Pack to handle the data traffic between the BP and the computer. This Access Point connects to the PC or laptop via Ethernet cable or wirelessly and is powered using a proprietary power adapter or laptop battery. One Access Point can connect to multiple MVN systems. For more information about the Access Point, see Section 5.6.
2.5 MVN Awinda backpack/suitcase with contents The MVN Awinda arrives in durable backpack with protective frame, which contains: 18 Wireless Motion Trackers (MTw) 1 Awinda Station 1 Awinda Dongle 2 Awinda Chargers MTw full body Velcro straps, including 3 shirts, headband, footpads, 2 pairs of gloves 1 Segmometer Quick Setup sheet Figure 7: Suitcase containing the MVN Awinda System 2.
2.8 MVN Awinda Charger The MVN Awinda Charger is capable of charging six motions trackers. Charging from empty to full takes about one hour. Figure 11: MVN Awinda Charger 2.9 “The Suit” Depending on the system, either a Lycra suit or a set of mounting straps are provided. The Lycra suit, has been designed for MVN Link and the straps for MVN Awinda. The generic term for either mounting type is simply “The Suit”.
2.10 Motion Trackers on the extremities The motion trackers are secured to the extremities – the head, hands and feet, using a headband, gloves and a foot pads, as can be seen in the figures below. Figure 14: Headband Figure 15: Gloves Figure 16: Foot Pads 2.11 MVN Ethernet Camera The MVN Ethernet camera is the Allied GigE Ethernet camera (supplied with MVN BIOMECH). Permits capture of synchronized video with MVN data. For more information about the MVN Camera, see Section 5.7.10.
3 Getting started 3.1 Installation of software Note: Do not connect your MVN System (either Access Point or Awinda Station) until software installation is complete (software installation includes installation of relevant drivers which can be finalized, when the hardware is connected). Run the downloaded MVN Installer (mvn_studio#_setup.exe). Install with “Administrator” rights. Follow the on-screen instructions. See 4.1 for details. 3.
Click the Calibration tab. Select N-pose or T-pose and follow the instructions to perform a sensor to segment calibration. Additional calibration poses are also possible if expert calibration routines are enabled. See Section 8.2. Pay attention to the calibration quality displayed in the Messages for Calibration window before applying the calibration to the character. See Section 8.2.6. Preview and Record. See Section 9. The live character can be seen in MVN Studio viewport. See Section 9.1.
therefore decrease performance. For optimal performance the ambient temperature should remain constant as much as possible during the measurement. NOTE: Never expose the motion tracker to strong magnetic fields. Xsens MT’s contain the absolute possible minimum amount of ferromagnetic materials (‘hard’ and ‘soft’ magnetic materials). Nonetheless, some minor components can be magnetized permanently by exposure to strong magnetic fields.
3.4.3 Suit, shirt, short maintenance To wash the suit, shirt, shorts remove all cables, BP and MT’s. Follow the instructions on the label inside the suit: Machine wash at 30°C – 85 F Do not bleach Do not iron Do not dry clean Do not tumble dry For the headband and gloves, remove the MTx and use only cold hand wash. 3.4.4 FabriFoam Velcro Straps Do not place in washing machine or dryer as this may damage the material. Hand wash in warm water. Use mild detergent if soiled. Rinse well.
4 Software As mentioned in Section 2.12, the MVN system is controlled MVN Studio. The installer of the software can be downloaded from www.xsens.com/mvn-studio-download. The instructions below detail the installation procedure. 4.1 Software Installation Note: Do not connect your MVN System (either Access Point, Awinda dongle, or Awinda Station) until software installation is complete. Run the downloaded MVN Installer (setup.exe).
Extension licenses or upgrade licenses can be activated on the dongle using the Software Activation tool, which can be started from Start Menu > Xsens > MVN Studio 4.x > Software Activation. 4.2.3 Network License Key When using a network license key, the red dongle needs to be used on a pc (server) that is running a service called ‘Sentinel LDK License Manager’. This service needs to be started by running an installer, which can be downloaded from: Xsens website: https://www.xsens.
5 Hardware 5.1 MVN Link The standard MVN System consists of a combination of hardware and software. The previous section described how to install the software. The following will provide an overview of the hardware, which includes the MTx’s, Body Pack, Sync Station and Access Point; and how to assemble the devices into the mounting system (Lycra suit or MVN Mounting straps). 5.
5.3 Body Pack (BP) and Battery Figure 18: Body pack and battery The Body Pack (BP) interconnects multiple strings of MTx’s and retrieves their data ensuring exactly synchronized samples. The collected data is transmitted by an optimized 2.4 or 5.0 GHz spread spectrum wireless link to the Access Point connected to the PC or via Ethernet cable. On the top of the Body Pack there are 4 connectors.
5.5 Battery Charger The CH5000 is a standalone desktop smart, standard battery charger with the added ability to recalibrate the fuel gauge on smart battery packs. 5.5.1 Using your Charger Place the charger on a flat, level surface away from sources of heat and moisture. Plug the DC connector from the power supply into the back of the charger and connect the power supply to the mains AC supply using the cable supplied. 5.5.
To recalibrate the fuel gauge, press the button on the front of the charger. The charger will automatically begin to charge the battery if the button is not pressed. The blue LED will flash to indicate that the battery is undergoing the recalibration cycle. During calibration the discharge resistors will be cooled by the fan. Removing the battery, or pressing the calibration button again will re-start the process from the beginning.
5.5.5 BP Power on/off and status LED Each BP has one push button with integrated LED, which controls its power state. Power on: Press button once, a single beep will sound and the LED will begin to blink slowly: 1 second on, 1 second off Press button three times, three beeps will sound and the LED will stop blinking. Power off: 5.5.6 BP Status LED The status LED changes color depending on the BP state. See Table 1 for an overview.
https://tutorial.xsens.com/video/wps-connection 5.6 Access Point (AP) The MVN System comes with one Access Point (AP) which handles the data traffic between the BP and the computer. The Access Point should be connected to the PC via Ethernet cable through the Ethernet port or using the supplied Ethernet to USB adapter. 1. LAN 1~4 LED Off: No power or no physical connection. On: Has physical connection to a local area network (LAN). 4. 2.4GHz LED / 5GHz LED a. Off: No 2.4GHz or 5GHz signal. b.
a. Press this button to power on or off the system. 9. Power (DC-IN) port a. Insert the bundled AC adapter into this port and connect your router to a power source. 12. LED On/Off button a. Press this button to turn on/off the backlight LED on the panel. 13. LAN 1 ~ 4 ports a. Connect network cables into these ports to establish LAN connection. 14. Reset button a. This button resets or restores the system to its factory default settings 5.6.
5.7 MVN (BIOMECH) Awinda 5.7.1 Wireless Motion Trackers (MTw) The MTw provides 3D angular velocity using rate gyroscopes, 3D acceleration using accelerometers, 3D earth magnetic field using magnetometers, as well as atmospheric pressure using the barometer. Combined with Xsens algorithms, 3D drift-free orientation is provided.
5.7.2 MTw LED Indications The following lists the LED indications of the MTw, which are a combination of the device states and the Awinda protocol states of the MTw. State Description Power-up Blinking. Docked and fully charged ON Charging Slow fade from ON to OFF as a percentage [%] of battery status. A slow cycle means an almost full battery. A quick cycle means an almost empty battery.
5.7.5 Awinda Station Front view of the Awinda Station, showing the LEDs. A description of the LEDs is provided in Section 5.7.7 below. On top are docking spaces for 6 MTw’s with recessed micro USB connectors. On the side is a foldable and rotatable 2.4 GHz antenna for maximum range. The external antenna of the Awinda Station enables a wireless range indoor/outdoor: 20/50 m (60/150ft).
5.7.7 Awinda Station Status LED The Awinda Station has five LED indicators. From right to left, these indicators are: LABEL LED DESCRIPTION CHRG OFF GREEN: When 12V power supply is connected (mains power supply). [CHaRGer functionality] STAT When no mains power supply is connected to the Awinda Station. OFF [STATus of the Awinda Station] OFF: When no power supply is present and when MVN Studio is not started. Power is from mains power supply and / or USB.
5.7.8 Awinda USB Dongle The Awinda USB dongle has the same wireless capabilities as the Awinda Station, in that it can accurately control the reception of data of up to 32 MTws. Given that the Dongle does not have an external antenna its range is shorter than the Awinda station; indoor/outdoor 10/25m (30/75ft). 5.7.9 Awinda USB Dongle LED The Awinda USB dongle has one white LED. State Description Radio Off LED off. Scanning for MTw’s Pulsating LED.
Straps are suitable for a majority of the adult population and can be placed directly on the skin for the close contact, or on top of the clothing for comfort. If worn over clothing, it is advisable to wear relatively tight-fitting clothes. The motion trackers are provided with a code indicating segment position. ‘L’ or ‘R’: left or right side of the body. Segment: An abbreviation of the segment name. While the straps are not labelled, the dimensions give an indication of their intended locations.
5.9.2 MVN Lycra suit A Lycra suit is provided with the MVN Link system. The MVN Lycra Suit is available in 5 different sizes (S, M, L, XL and XXL). Before putting on a suit, ensure that the size is appropriate; refer to Table 7 in the appendix for this information. The suit must be tight fitting, therefore choose the appropriate suit size. Note that the fabric is stretchable, a medium size suit can fit to both a short muscular athlete (e.g., 1.60 m, 70 kg) and a tall slim person (e.g., 1.75 m, 65 kg).
https://tutorial.xsens.com/video/preparing-hardware-mvn-link 1. 2. 3. 4. Unzip all zipper channels on the suit Secure each MT into the suit using the Velcro patches on both the trackers and the Lycra. Connect the cables between strings of trackers. Ensure that all MT’s are in the approximate locations as indicated in the tutorial video. 5.9.3 Putting on the remaining Motion Trackers When the suit has been put on, motion trackers for the head, hands and feet will remain outside of the Lycra.
Table 2: Description of MT locations Location Abbreviation Optimal position Foot FOOT Middle of bridge of foot Lower leg LLEG Flat on the shin bone (medial surface of the tibia) Upper leg ULEG Lateral side above knee Pelvis PELV Flat on sacrum Sternum STERN Flat, in the middle of the chest Shoulder SHOU Scapula (shoulder blades) Upper arm UARM Lateral side above elbow Fore arm FARM Lateral and flat side of the wrist Hand HAND Backside of hand Head HEAD Any comfortable positio
6 MVN Studio MVN Studio is easy-to-use software, which can be used for real-time viewing and recording. Off-line playback, analyzing and editing of previously recorded sessions are also possible with MVN Studio. Figure 20 shows a typical view of MVN Studio when a recording has been made. Figure 20: MVN Studio interface The main tool bar at the top of the MVN Studio interface is displayed in Figure 21 below. Using this toolbar, much of the functionality of MVN Studio can be called.
6.1 Status Bar At the bottom of the MVN Studio interface is the status bar. It is important to pay attention to the icons shown here, as they give important information about the status of the system.
7 Workflow and Functionalities in MVN Studio MVN Studio is designed for optimal flow of the steps required for recording and analyzing motion. Different workflow items become active at various stages. Figure 23: The workflow toolbar gives the user an optimal interface setup per functionality: Hardware and Fusion Setup, preview and record, playback and editing and analysis 7.1 New session A new session is created during the workflow stage “Hardware and Fusion Setup”.
Sync Station, see 7.5 Configuration Group, see 7.6 7.2 Configure an MVN System When the user has clicked “Add Configuration” and selected “MVN System” the following configuration window will appear. The image below shows the expanded and views and details how to modify the settings. Note that the Sync Settings dialogue is available only with an MVN BIOMECH license. Expanded view Collapsed view 7.2.
7.2.7 Expanding and Collapsing Views On first use, one system is detected and the expanded view is enabled. It is possible (likely) that after a number of times using the system, or if many configured items are in the list this detail is no longer required. For this reason it is possible to still have an overview of the system status in a more compact view. 7.2.8 View Hardware Status For MVN Link this view is only needed for troubleshooting or relocating trackers.
7.2.12 Scenario Depending on the type of measurement you will carry out, select the type of scenario that will ensure the best results, and minimize post-processing. The scenarios available include: Single Level Multi Level Pelvis Fixed Pelvis Fixed Tight Soft Floor This scenario assumes that the subject will be walking on level terrain This scenario assumes that the subject will be walking on terrain or varying height, e.g. climbing stairs.
Figure 25: Example of camera configuration window If no pictured is displayed, if the image is jagged, or no camera is found, install the dedicated driver, found in C:\Program Files\Allied Vision Technologies. You may have to restart MVN Studio for the camera to be found after this is installed. If no video data is displayed, check or uncheck the Use jumbo packets option to resolve the issue.
7.5 Configuring the Sync Station The Sync Station is dedicated hardware for synchronizing between MVN BIOMECH Link and third party systems. The user will note that when MVN BIOMECH Link is selected, the text beside Sync Settings states “Not sync capable”. The Sync Station must be inserted for synchronization with MVN BIOMECH Link. Click 7.6 to configure the sync settings. For details about each setting, refer to Section 23.
7.8 Hardware Status To view the Hardware Status, Select the or in the configuration window. Hardware status shows a list of all trackers and masters detected by MVN Studio. The figures below show the hardware status interface and Table 3 details the meaning of the colored markers. This menu can be edited while the Configure Session window is also open, instructions for editing can be found below. When the Configure Session is not open, this interface is read-only.
When all trackers have been detected, it may take some time (up to 30 seconds) to secure the network and for the 3D character to appear. Additionally, it may take several seconds for the battery status to display, please be patient to allow the information from each tracker to be transmitted to MVN Studio. 7.8.1 Relocating motion trackers Each Xsens motion tracker has a unique location ID which relates them to the limb segment they should be placed on.
7.8.3 MVN Awinda: Changing Radio Channel In the Hardware Status window, either right click or double click the number under the letters “Ch”. A small menu appears providing the option to change radio channel, reject unused trackers or “forget” system. In general, when working in an environment known to have a lot of WiFi traffic, it is best to select channel 11, 15, 20 or 25. See Section 19.12.1 for background information. 7.8.
The prop tracker must be configured in the menu Options >Configure Props. Here, the type of prop can be selected (crutch, sword, gun, diemaco, golf club, prop [this is simply a right-handed axis]), which can be assigned to a given suit and a given motion tracker ID. Generally the motion tracker on the prop is detected automatically when clicking ‘Apply’ in the Prop Configuration window. If this does not occur, go to Tasks >Re-initialize suit(s).
MTw MTx 7.10 Navigator When a new session has been created, suit-specific variables can be viewed in the navigator. This generally appears automatically on the left side of the window. If not, it can be found using View >Navigator. In the navigator, parameters of the suit can be seen, including the Suit ID and the color of the indicator above the head of the 3D character. While this is possible with only one system, it becomes essential when multiple systems are being recorded at once.
8 Setup The setup workflow stage consists of three parts; input the subject’s body dimensions, data fusion and sensor to segment calibration. The calibration procedures are only available once the MVN system is connected and the 3D Character has appeared in the view port. When a file has been recorded this icon remains active to enable changes to body dimension inputs. NOTE: It is not possible to save a calibration file, when a recorded file is open.
Figure 31: Error generated if recording attempted without subject height and foot length. In addition to these basic measurements, other body segment dimensions can be adjusted for subjectspecific anthropometry. The model-based values are presented between brackets, as Figure 30 shows, e.g. Knee Height (48.6). The scaling model is based on the height of the subject without shoes. The shoe sole height can be added as an offset to the feet.
8.1.1 Offline Body Dimensions In order to facilitate data collections, body dimensions can be measured and input into MVN Studio without connecting an MVN suit through the ‘Offline Body Dimensions’. This feature allows users to save body dimensions as an MVNA file prior to instrumenting a subject. Later, when the system is connected, the file can be loaded again from the Body Dimensions panel.
Figure 32: T-pose with body segment dimensions Acromion Ant. sup. iliac spine Greater trochanter Lateral epicondyle Lateral epicondyle Radial styloid Lateral malleolus Figure 33: Anatomical landmarks on leg (left) and arm (right) Document MV0319P.N 45 © Xsens Technologies B.V.
8.2 Calibration Segment calibration is the step required to align the motion trackers to the segments of the subject. Watch the video on the tutorial portal for instructions on how to perform the calibrations: https://tutorial.xsens.com/video/setup-and-calibration-mvn-link. Creating a good calibration is of utmost importance in order to ensure accurate results. For this reason, the calibration procedure should be carried out in a magnetically-sound environment.
calibration). For short recordings, the drift of the character is typically limited to a few cm. With multiperson capture, the characters can drift apart after a while. Usually this can be fixed in the animation package used for retargeting the motion data to a virtual character.
8.2.4 Expert Calibration: Hand Touch It is important for the operator to determine if the hand touch is required - in general it is not necessary. Sometimes it is difficult to get very accurate hand data, even when the N or T pose has been carried out well. For this reason it is sometimes needed to carry out a Hand Touch calibration. Note that a good Npose is necessary to obtain the best results. When performing the calibration, take care of the following: Place the palms of the hands together.
There are four levels of calibration quality: good acceptable poor fail Generally, a ‘good’ or ‘acceptable’ quality indication is sufficient. If the calibration result is not ‘good’, the reason is indicated in the text below. Read the advice provided to improve the result. If the result is “acceptable”, consider repeating. A ‘poor’ quality indicates that there is too much movement during the calibration or the magnetic field is disturbed.
9 Preview and Recording 9.1 Preview During the Preview and Recording stage of the workflow, the viewport is active. There are a number of viewing possibilities, the 3D character in the 3D viewport and orthogonal views. Select the number of windows to view at one time. Figure 39 is an example of a four window view showing the 3D view and three different orthogonal views. To select which type to view, Right Click and select from the drop down menu, as indicated in the figure (or use the shortcut keys).
9.1.1 Viewport Icons The icons above the viewport can be selected to show and hide various parameters, as detailed below.
9.1.2 Views Right click on the screen (or use the shortcut key) to choose one of the following camera viewpoints: Menu command (+shortcut) Action Free move (V) The camera is still. The character may go out of view of the screen. Trailing (T) The character is always in view. The pitch of the camera is fixed. The distance of the camera to the character is fixed. The height of the camera follows the height of the pelvis. The camera heading is determined from the previous and new character position.
It is important to note that when a reset is carried out, the subject should stand still in a magnetically clean environment. Depending on the rest, some time is needed to build up good history again. Character Reset (menu > Tasks > Character Reset, or Ctrl+Alt+F): This command partially resets the filters, but keeps valuable information that was stored; the result is that the character will remain in its horizontal position, and a shorter stabilization period is required (up to 30 s).
9.1.5 Save and Restore Layout To the right of the graph icon are two icons indicating the possibility to save and restore layouts of the interface. To save a layout, use the icon directly to the right of the graph icon, the layout currently in view will be saved. Give the layout a name, in the drop down menu that appears. To use a saved layout, click the rightmost icon “Restore Layout” and select the name from the drop down menu that appears.
9.3 Add comments after recording Adding comments after a recording has finished can be very useful in a later stage when you are opening the recordings. The popup dialog to add comments after a recording can be enabled or disabled (menu > Preferences > Interface > User Interface Show popup dialog for file comments after recording). To view the comments from the open file dialog in MVN Studio or Windows Explorer, you will have to add the ‘comments’ column.
recovery file (MVR) that can be used to recover the data captured. A message will ask if you want to use a recovery file. This file has the same name and location as the corresponding MVN file but with a “MVR” extension. The file is used by MVN Studio to recover the corrupted MVN file. 9.5 Markers During or after recording, markers can be added to the timeline to indicate events. During recording, add a marker by clicking the Add Marker icon or by using the ‘+’ key or ‘space bar’.
9.6 Network Streamer The network streamer sends the poses of the active window (playback or real-time), both UDP and TCP are supported by the network streamer. The UDP Protocol is unidirectional, and contrary to TCP (Transmission Control Protocol, RFC 793) it is stateless and does not require the receiver to answer incoming packets. This allows greater speed. You can use a network monitor on another or same PC to receive this stream, or write your own receiver in another application.
Figure 42 above shows the Network Streaming preferences. The table below summarizes the functionality of each selection. Please refer to the Real-Time Network Streaming Protocol Specification for further details. Datagram Description Position + Orientation (Quaternion) Positions and orientation of each body segment, orientations in quaternion format, position units are in meters. This is the most accurate and preferred format for new application development.
9.7 Network Monitor MVN Studio also implements a Network Monitor that can receive the MVN network stream of motion data. Note that this is mean only to monitor a network stream and no further functionality is provided than viewing (i.e. no saving, recording, editing etc). To open a network monitor in MVN Studio, go to File >Open Network Monitor or press “Ctrl+M”, to obtain the menu shown in Figure 43.
10 Playback and editing When a file has been recorded, various new elements become possible, including playback of the recorded file; depending on whether or not the video was used, this will also involve synchronized video data. Furthermore, although intended for the analysis workflow stage only, graphs are available during the Playback and Editing workflow stage to help in some post-processing tasks. Graphs are described in detail in Section 11.1.
However, if there is a larger offset between the MVN and video data, time-synchronization can be manually corrected using the sliding bar under the video. Drag the bar or use the numbers or the arrows to change the offset [ms]. The offset is applied to the whole file. Any clock skew between the camera and the MVN system is automatically estimated and corrected. Figure 44: Video synchronization sliding bar 10.
Figure 45: Contact point Table 5: Potential contact points in MVN Studio Contact point Description HeelFoot Heel of the foot FirstMetatarsal Inside ball of foot FifthMetatarsal Outside ball of foot PivotFoot Center ball of foot TibialTub Bony elevation on upper part of the shinbone (tibia) GreaterTrochanter Eminence on the upper part of the femur IschialTub Buttock (left and right) Sacrum Base of the Spinal Column Central Buttock Buttock PX Bottom of sternum T4SpinalProcess Vertebra
To scrub, drag the time line scroll bar ( ) to the left or right. Step through the time frames using the left and right cursor or keep it pressed to move very slowly though the file, frame by frame. Figure 46: Contact points on the 3D viewport and the contact editing menu 10.3.1 Selection of samples The left mouse button (and drag) will set a contact for the selected contact point. The color of the userdefined contact point will be slightly darker than the color of the original detected contact point.
10.3.2 Contact point editing options 10.3.2.1 Remove user-defined Revert to the original recording for the selected samples. Remove user-defined aiding refers to the positions and floor levels set, as remove user-defined contacts refers to the contact points of the segments. Reprocess to apply changes (see Section 10.3.2.7). 10.3.2.2 Ignore contacts globally Removes all detected contacts for all segments. Figure 48: Example of ignore contact globally 10.3.2.
Note: in MVN Studio, height is indicated by ‘Z’. Figure 49: Set position menu during contact point editing The SD slider sets the standard deviation, which is an indication of how much the aiding point can be trusted in combination with the computed position of the MVN Fusion Engine. This option can also be used creatively for example to create a “soft” landing on a mattress. With the ‘Force no contacts’ options, no other contacts will be detected during the selected frames.
10.3.2.6 Floor level Sets the height of the floor. Multiple floor levels can be set in one file. The current floor level is presented in the dialog; see Figure 51 for an example. Figure 51: Set floor level menu Right mouse click on a contact bar to set the floor height to the height of that contact. The contact detection will now be applied on the new floor height for all following samples. Left mouse click and drag on the advanced bar allows you to set a floor height for a range of frames 10.3.2.
Reprocess progress bar Figure 52: Contact editing reprocess bar If many contacts have been inaccurately detected specifically on one side of the body, it is likely to be caused by inaccurate calibration. Check that the MT’s of the legs and pelvis have not moved. Also check that the body dimensions are correct. If necessary, repeat a basic calibration (N or T pose).
11 Data Analysis The final stage of the work flow is ‘Data Analysis’. The major feature of the analysis stage is kinematic graphs. 11.1 Graphs In the analysis workflow stage, a graph appears in the interface. To view a graph of a given parameter, click and drag the parameter from tree view to the graph. Two types of graphs are possible: time vs. parameter and parameter vs. parameter (Coordination [or phase] Plots). 11.1.1 Parameter vs.
11.1.3 Graph handling Zoom and pan in the graph using the icons in the toolbar. The time on the time vs. parameter graphs conforms to that shown in the time bar. 11.1.
11.1.7 Pan To use the pan function, enable “no auto scaling”, click in the graph area with the left mouse button and drag up or down, to pan. Note that it is not possible to pan to an area with no data. When data is available beyond the limits of the vertical axis it is possible, using the cross bar to pan, and also using a purple scroll bar, which appears on the side of the graph when there is a large difference between vertical values, as Figure 54 shows.
11.2 Cascade / Tile windows Multiple trials can be opened simultaneously and played and edited. Viewing a live performance is also possible in playback. Use the ‘Window >Cascade / Tile’ menu to select the window layout. 11.3 Linked views When multiple windows are active, their views can be linked. Upon enabling Linked Views, the scene of all windows will be reset such that the origin faces the same direction. When the view in one window is changed, the view in the other window will change accordingly.
12 Saving and Exporting When a recording has been made, two files are created and saved automatically, one with the file extension “.mvn” and the other with the file extension “.mvns”. If synchronized video data is recorded, a movie file “.mpg” is also saved automatically. MVN (MVN native file) is the most comprehensive format and contains all measured inertial sensor data, and all kinematic data of each segment. It is a binary proprietary format and can only be used by MVN Studio or by using the SDK.
12.1.2 Output filtering: LXsolver The MVN fusion engine allows some laxity between joints to allow for small errors due to for example soft tissue movement. In the FBX export file, the positions and orientations of all segments as captured are exported. In BVH, only the position of the root (pelvis) is exported. The other segments are rigged, based on Euler angles with respect to the previous segment.
In the default BVH hierarchy, the character is in a T-pose. Use the 3ds Max exporter to write a neutral pose (arms parallel to body). Use the Poser exporter to reduce the number of chest segments from 4 to 2. The motion section begins with the keyword ‘MOTION’. This line is followed by the number of motion frames by the keyword ‘Frames’ and ‘Frame Time’, indicating the sampling rate of the data.
Figure 56: BVH Preferences Menu 12.2.1 Frame skip The frame skip number (n) is used to reduce the frame rate of the output. The exporter will perform down sampling by skipping every n frames (n = 0 to 10) of the original file (after smoothing) in the output. Note that if no smoothing is specified, no smoothing will be applied when using frame skip. The output rate is given by: original sample rate / (1 + skip factor).
12.3 C3D C3D means “Coordinate 3D”; as the name suggests it is a file format designed to contain 3D coordinate data, usually in the form of bony landmarks. It has also been designed to contain analog data. The 3D and analog samples are interleaved, frame-by-frame, throughout the data in a straightforward manner. C3D data can contain 3D, 2D, analog data or a combination.
12.3.1 Points exported in C3D Exporter For an illustration of the location of the points, see Figure 68.
12.4 FBX Figure 58: FBX Preferences Menu FBX (Filmbox) is a platform-independent 3D file format which gives you access to content authored in software packages such as MotionBuilder, Maya, Unity or Softimage. For some software packages, an FBX plug-in should be installed. FBX files contain both position and orientation information of all 23 segments. The FBX file will also contain the frame time format. Go to >Options >Preferences >Exporters >FBX … and select the timestamp output mode.
12.5 MVNX MVNX (MVN Open XML format) files are provided. These are XML files that can be opened in programs such as MICROSOFT EXCEL, ACCESS and MATLAB; see section 22 for help importing these files to MATLAB and EXCEL. MVNX contains as default, 3D segment and position data. Additional values can be exported as Figure 59 shows, including: 3D Position, linear and angular acceleration and velocity of all 23 segments. 3D Joint angles of 22 joints.
The entire MVNX structure is as follows: X Y Z =“r11 r12 r13 r21 r22 r23 r31 r32 r33” X Y Z etc. etc.
etc. The MVNX file starts with the XML version number and a reference to the DTD (Document Type Definition). Then the root element “mvnx” with a reference to the XSD (XML Schema Definition) and the MVNX version This is followed by a field “mvn”, containing the MVN Studio version and build details with which this MVNX file was produced, followed by the comments that were added to the original recording:
The sensor data is simply a list of the names of segments measured with the MT’s: < sensor label ="Pelvis"/> < sensor label ="Head"/> < sensor label ="RightShoulder"/> etc. The “joints” section is a list of the names of joints contained and the segments and connections a given joint: Pelvis/jLeftHip LeftUpperLeg/jLeftHip etc.
The selection in the preferences menu determines the MVNX contents. Orientation and Position are mandatory, all others are optional and may depend on the license.
The numbering is presented in the table below.
12.6 Export Movie Exporting movie data enables the user to export the 3D viewport of MVN Studio to either .m4v or .avi. this facilitates presenting MVN information to audiences without the need for installation of MVN Studio, Select the export format, resolution and export frame in >Options >Preferences >Exporters >Movie Exporter. Document MV0319P.N 85 © Xsens Technologies B.V.
13 Features of MVN Studio A range of additional features become available when using another license for MVN Studio PRO. These are summarized in Table 6.
13.1 Plug-ins MVN Studio PRO and MVN Studio BIOMECH are equipped with the following plug-ins: MVN Time Code and Remote Control Plug-in The MVN time code and remote control plug-in is designed in case synchronization of single or multiple MVN systems with other systems is required. The data of a MVN system is time stamped during recording, so it can be lined up afterwards with data of other systems i.e. cameras, audio, etc.
14 MVN Ethernet Camera MVN Studio 3.0 has the ability to record synchronized MVN and video data. This is possible using the Ethernet camera (Prosilica GS650) provided with the PRO system. The camera is a high quality professional GigE camera with a C mount. The GigE interface enables the use of long cables (max 100m) and standard 1 Gigabit Ethernet cards for interfacing.
14.2 Camera driver The camera should be available to MVN Studio when connected. The camera driver is installed together with the software. However, depending on your network card specification and the setup used, in some cases MVN Studio does not find the camera, or the performance is not as expected, re-installing the driver may solve this issue. A dedicated driver (Prosilica GigE Filter Installer 1.20.exe) is available and can be found in folder ...\Program Files (x86)\Allied Vision Technologies\ 14.
Please check the Ethernet Network Card settings in the Windows Device Manager to enable support for “Jumbo Frames” and adjust it to its maximum value. The “Jumbo Frames” might also be called “Maximum Frame Size”. Figure 61: Screenshot illustrating setting the correct Jumbo Frame settings in the Device Manager dialogue. 14.
15 Xsens Peripheral Software 15.1 Magnetic Field Mapper (MFM) When a motion tracker is mounted to an object that contains ferromagnetic materials, the measured (Earth) magnetic field can become distorted, causing errors in measured orientation.
15.4 Software Activation Tool: Applying an Update You can use the Software Activation tool to apply an update to the licenses stored in your Sentinel protection keys. To update the licenses in the Sentinel protection keys: 1. Launch the Software Activation tool from the start menu or help menu in MVN Studio 2. Click “Show advanced options”. 3. Click “Apply license file (V2C)”. 4. Click “Next” and browse to the V2C files you have received to open it The license is activated/updated. 15.
16 Troubleshoot Problem Solution Device driver error Awinda Station with docked MTw’s results in "Driver Software Installation" error. See figure to the right displaying the pop-up warning: This is a timing issue because Xsens motion trackers send data to the PC continuously to guarantee a fast set up time. To solve, remove the tracker from the station then redock. The suit does not connect. Check battery levels. Check ‘Hardware status’ menu (Section 7.8). Check Suit configuration (Section 7.2.
Problem Solution Live preview is active but recording is not possible Enter the subject dimensions: body height and foot size (Section 8.1). Perform an N-pose calibration (Section 8.2.2). Make sure to apply. MVN Awinda: Make sure that no Synchronization settings have been saved to the Awinda station Directly after the T-pose calibration, the axes of rotation of the subject do not correspond with 3D character. Place MT on the pelvis flat on the sacral bone with Z axis pointing away from subject.
Problem Solution See Section 19.13 for the specification of the recommended computer system. During recording, the rotations of some segments do not correspond with the 3D character. Check if MT’s have not moved in the suit. Perform a new calibration. Move calmly for 10-20 seconds directly after calibration. Check for magnetic disturbance (Section 19.2). Stand still and perform a Character Reset (Ctrl+Alt+F). During recording, the rotations of some segments are not smooth. Check wireless connection.
Problem Solution Check to make sure that all trackers are in the correct locations Character walks in place or is seen flying across the screen Contact support www.xsens.com/support for assistance. The battery from one MTw tracker drains much faster than the other trackers MVN Studio fails to connect with suit. Error code #40 Contact support www.xsens.com/support for assistance. Document MV0319P.N 96 © Xsens Technologies B.V.
17 Warranty and liability Xsens Technologies B.V. warrants the products manufactured by it to be free from defects in material and workmanship for a period of 2 years from the date of delivery. Products not subjected to misuse will be repaired, replaced or credit issued at the sole option of Xsens Technologies B.V. Contact support: www.xsens.com/support for return material authorization (RMA) prior to returning any items for calibration, repair or exchange.
18 Regulatory Notices MVN Awinda 18.1 Radio Frequency Exposure and Emission The MTw2, Awinda dongle and station contains a small radio transmitter and receiver. During communication with the Awinda Master it receives and transmits radio frequency (RF) electromagnetic fields (microwaves) in the frequency range 2400 of 2500 MHz. The output power of the radio transmitter is very low. When using the system, you will be exposed to some of the transmitted RF energy.
Radiation Exposure Statement for Awinda Station: This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment should be installed and operated with minimum distance 20cm between the radiator & your body. This transmitter must not be co-located or operating in conjunction with any other antenna or transmitter. This MVN Awinda product contains FCC ID: MTw2: QILMTW2-3A7G6 Awinda Station: QILAW-A2 Awinda Dongle: QILAW-DNG2 Document MV0319P.
18.3 Declaration of Conformity 18.3.1 CE Declaration of Conformity MTw2, Awinda Station, Awinda Dongle Document MV0319P.N 100 © Xsens Technologies B.V.
18.3.2 FCC Declaration of Conformity MTw2 Document MV0319P.N 101 © Xsens Technologies B.V.
18.3.3 FCC Declaration of Conformity Awinda Station Document MV0319P.N 102 © Xsens Technologies B.V.
18.3.4 FCC Declaration of Conformity Awinda Dongle Document MV0319P.N 103 © Xsens Technologies B.V.
19 Appendices 19.1 Lycra suit sizes overview Table 7 is an overview of the typical height and weight of a subject that will fit into a given suit size. While this is generally accurate, it is an indication, therefore test the suit size, to ensure that it is tight enough to keep MTx’s in place during measurement while remaining relatively comfortable. Table 7: MVN Lycra Suit sizes Size Body height Weight S 1.55 - 1.65 cm 5'1'' - 5'4'' ft. 50 – 65 kg 110 – 143 lbs. M 1.65 - 1.70 cm 5'4'' - 5'6'' ft.
Figure 62: Show magnetic disturbances In Figure 62, the MT on the left hand shows a warning and is probably close to a wall or an iron object. The rest of the circles are green which indicates that the magnetic field is suitable to perform a calibration. The advice is to move to a different location in such way that the red circle becomes yellow or (preferably) green. When some circles are green and some are yellow or red, try to find a spot in the room or building where the red circles disappear.
right foot. The lower graph coincides with the colored indicators in the 3D and orthogonal views of MVN Studio, when the magnet icon is active. As Figure 63 shows, the magnetic field indicators are green; this is represented as a line close to zero in the Mag Field Norm plots shown for the head and the right foot. This shows that the magnetic field is sound for measuring. Figure 63: Mag Field Norm coincides with green Mag Field indicators. Top graph is Mag Field of the MT on the Head.
From the same recording, Figure 64 shows that when the subject has moved, they have approached a ferromagnetic material. This is known because the Mag Field Norm increases, in particular for the right foot, as it increases above 1.5. If this value increases further and remains high for longer than a few 30 seconds (usually less than 2 can be dealt with in the algorithms used in MVN Studio) then this area should be avoided, in particular during calibrations, but if possible, also during measurements. 19.
q0 2 q12 q2 2 q32 R = 2q1q2 2q0 q3 2q1q3 2q0 q2 2q1q2 2q0 q3 q0 q q2 q3 2 2 1 2 2q2 q3 2q0 q1 2q2 q3 2q0 q1 q0 2 q12 q2 2 q32 2q1q3 2q0 q2 2 1 2q2 2 2q32 2q1q2 2q0 q3 2q1q3 2q0 q2 2q1q2 2q0 q3 1 2q12 2q32 2q2 q3 2q0 q1 2q1q3 2q0 q2 2q2 q3 2q0 q1 1 2q12 2q2 2 For further information on quaternion operations and rotations, refer to the book: J.B. Kuipers. Quaternions and Rotation Sequences.
Global reference frame: X positive when pointing to the local magnetic North (red). Y according to right handed co-ordinates (West) (green). Z positive when pointing up (blue). Local coordinate frame: Body: segments in anatomical pose: Origin: center of rotation (proximal) X forward. Y up, from joint to joint. Z pointing right. This difference in coordinate systems will not affect results. After the calibration procedure, the right heel of the character is set at the origin (0,0,0).
BY A Body frame BZ BX A A Segment A S YA Sensor frame S XA BY C BZ B BX GZ B Segment B Global frame Sensor GY GX Figure 66: Global and local coordinate frames in MVN Studio 19.6 Anatomical model 19.6.1 Definition of segment axes To describe motion capture data in clinically meaningful data, e.g. joint rotations, it is necessary to define a coordinate reference frame attached to the body segment.
19.6.2 Bony/anatomical landmarks The positions of bony/anatomical landmarks with respect to the joint origin of the related segment are presented in the MVNX file, see the tag in the section. Segments are assumed to be rigid bodies. Positions of anatomical landmarks in the global frame (G) can be found by rotating the vector of the landmark in the body frame (B) to the global frame and adding the global position of the origin.
Upper body T8, ribcage, neck and shoulders Right arm and shoulder Left leg and foot Pelvis, L5 and right upper leg Document MV0319P.N 112 © Xsens Technologies B.V.
pPIJ pPX Figure 68: Selection of anatomical landmarks. Above, anterior view. Below, posterior view. Document MV0319P.N 113 © Xsens Technologies B.V.
19.7 Segment axes definitions and Origin Definitions Note: To ease comparison between the MVN segment co-ordinate systems with the International Society of Biomechanics recommendation, currently based on optical position tracking systems, the ISB recommendation is presented next to the MVN definition. The MVN segment axes definition and origins have been chosen as closely as possible to the ISB recommendation where whenever possible.
19.7.2 Neck: Segment 6 MVN ISB O jT1C7 Not described in ISB X Perp. to Y and Z Pointing forward Y jT1C7 to jC1Head Z Pointing right Note: The neck segment is not measured directly in MVN; it is calculated using a model of the neck. 19.7.3 Head: Segment 7 MVN ISB O jC1Head Not described in ISB X Perp. to Y and Z Y jC1Head to TopOfHead Z Left Ear to Right Ear Note: Position of Ears are not measured but assumed to be on the same height. 19.7.
will move with segment T8 which is measured with the MT of the sternum. MVN does not measure the clavicle and is undefined in MVN. 19.7.5 Upper Arm (Humerus): Segment 9 Right and Segment 13 Left There are two segment coordinate systems described in ISB. The system described below is option 1. MVN ISB [iii] O jRightUpperArm GH jLeftUpperArm GH GH X Sagittal plane Pointing forward Line perp.
19.7.7 Hand: Segment 11 Right and Segment 15 Left MVN ISB [iii] O jRightWrist jLeftWrist ISB defines origins and axes for each: Of the 5 Metacarpals 14 phalanges X Pointing forward Y Top of Hand to jRightWrist/jLeftWrist Pointing Vertical Z Perp. to X and Y Pointing right Note: In MVN, the joint center is the midpoint between the styloids. No metacarpals are measured in MVN. This description is for the anatomical pose.
Note: In ISB and MVN, the origin is in center of hip rotation, which is the head of the femur. Della Croce [iv]: midpoint LE and ME. In the MVN model, the lateral and medial epicondyles are on the same height. 19.7.9 Lower Leg (Tibia/Fibula): Segment 17 Right and Segment 21 Left MVN ISB [ii] O jRightKnee jLeftKnee IM IM X Perp. Y and Z Pointing forwards Line perp. to torsional plane of tibia/fibula. Pointing anteriorly Y Right: jRightAnkle to jRightKnee Left: jLeftAnkle to jLeftKnee Line perp.
19.7.10 Foot (Calcaneus): Segment 18 Right and Segment 22 Left MVN ISB [ii] O jRightAnkle jLeftAnkle IM IM X Sagittal plane forward Line perp. to frontal plane of tib/fib in neutral configuration. Pointing anteriorly. Y Vertical (aligned with gravity, pointing up) Line coincident with long axis of tibia/fibula, in neutral configuration. Pointing cranially Z Perp. to X and Y Pointing right Line perp. to x- and Y- Note: In the MVN model lateral and medial malleoli are on the same height. 19.7.
Note that all representations of the joint angles are based on the same quaternion or rotation matrix. The differences lie only in how the angles are extracted (represented) from this rotation. The International Society of Biomechanics (ISB) has proposed standards for rotation sequences for the lower [Wu et al, 2002ii] and upper body [Wu et al 2005iii]. 19.8.
19.8.3 Joint angle outputs Below is an overview of all joints available in MVN and a short description.
19.9 XKF-HM Xsens Motion tracking works on the basis of Kalman Filtering. In its simplest form, it combines the different information sources to calculate the desired parameters. This has an impact on how the systems should be used. The more historically correct data has been measured (in good magnetic environments for example and with enough physical movement of the motion trackers) the more robust the filter can be. For this reason we advise to calibrate in a magnetically sound environment (See Section 3.
If a reset is required during measurements, it is also advised that the subject stands still when the reset is enabled and remains still for 30 seconds thereafter. In these 30 seconds, the gyroscope biases are estimated and the uncertainties minimized. If there are issues regarding problematic magnetic field distortions follow the instructions below: 1. Configure the system (see section 7.1). 2. Move all motion trackers in smooth 3D, circular motions. This can be done with hardware 1.
MTw's across the wireless network to within 10 microseconds, achieving 'wired like' system performance. The Awinda protocol is developed such that no data is ever lost. If individual packets are missed, there is some room to contain data temporarily. This buffered data is then retransmitted.
19.13 System Specifications Recommended computer system Operating system Windows 7/8 (64 bit) Processor Quad core or higher (2.7 GHz or faster) Hard drive SSD 256 GB or more Memory 8 GB RAM (64-bit) Graphics card Hardware acceleration for DirectX 11 Dedicated memory 512 MB or more Network card Gigabit Ethernet, support for jumbo frames (9014 Bytes) USB ports USB 2.
Communication Interface Wireless (WiFi or Awinda Protocol) Wireless range radius (max) MVN Awinda Station Awinda dongle Outdoor 150 meter (492 ft.) ~50m (164 ft.) ~20m Indoor open space 150 meter (492 ft.) ~20m () ~10m Indoor office 50 meter (164 ft.) ~20m () ~10m Wireless receiver units: MVN Link MVN Awinda Number of Wireless Receivers 1 Access Point 1 Awinda Station or Awinda Dongle RF technology WiFi 2.4GHz, 5.0 GHz IEEE 802.15.4 PHY 2.4GHz Interface Ethernet USB 1.1 or 2.
Tracker Performance Static accuracy (Roll/Pitch) 0.2 deg Static Accuracy (Heading) 0.5 deg Dynamic Accuracy 1 deg RMS Accelerometer range MTx: ± 160 m/s2 (16 g) MTw: ±160m/s2 (16g) Gyroscope range ± 2000 deg/s MVN Performance MVN human model MVN uses a 23 segment biomechanical model with 22 joints. Each joint is specified by statistical parameters for 6DOF joint laxity. An advanced spine and shoulder model is used that computes the kinematics of the spine and shoulder blades.
MVN Fusion Engine 3D translation capture ~1% error in traveled distance (without external aiding). Advanced external contact model detects body-world contacts, to enable crawling, sitting, cartwheel etc. Various friction models (slippage etc.) are possible.9 Seamless fusion with aiding technologies possible, e.g. 3D position from optical/GPS, or 2D image correspondences.9 Magnetic environment Local, permanent disturbances Full immunity to any magnetic distortions of knee and ankle joint.
20 Contact point editing examples The following section illustrates how to use the contact editing toolbar. 20.1.1 Example 1 In the originally recorded MVN file, a contact on the mid foot has been wrongly detected. The result is an unlikely position of the foot segment with respect to the lower leg and a discontinuity in the position of the total character. Removing this contact will improve the data. Click on the foot segment.
After editing the contact points, press the reprocess button or ‘Ctrl+Shift+P’. The MVN Fusion Engine will now re-compute all kinematics using the original inertial sensor data taking the overruled contact points into account. 20.1.2 Example 2 In the originally recorded MVN file, the foot is already on the ground but the contact is detected too late. The result is that the character seems to stick at a wrong contact and the foot slides back. Click on the foot segment.
21 Working with different applications 21.1.1 Autodesk 3ds Max In 3ds Max, a Biped system provides direct input of BVH files, including keyframe reduction and footstep extraction. Choose the 3ds Max output format when exporting to BVH. The exporter will apply a neutral pose hierarchy instead of the T-pose hierarchy. The neutral pose for the Biped places the figure upright along the +Z axis, facing forward along the -Y axis, left hand on the +X axis.
Poser 7 note: There is a known issue in Poser 7 regarding figure orientation. It will introduce an odd twist in the orientation of the segments. Please contact Poser support for information about an update. 21.2 MotionBuilder workflow To import FBX in MotionBuilder, the MVN script called MKMVN01.py (which can be found in %AppData%\Xsens\External\MotionBuilder\Templates\MVN) should be copied to one of the following folders: Windows 7 64-bit, MotionBuilder 64-bit installed: C:\Program Files\Autodesk\Motion
4. The skeleton is a character in MotionBuilder and the control rig contains the captured motion. You can now simply merge another character in the scene and transfer the animation by using the character input option of MotionBuilder. You can also save the animation in the character controls. Document MV0319P.N 133 © Xsens Technologies B.V.
22 Importing MVNX files to other programs 22.1.1 Import to Microsoft Excel File and open the MVNX file. It is likely that the following warning is generated. Click YES. Next the following menu will pop up: As in this example, select the XML source pane option. Another warning message appears: Click OK. The window will now look like: Document MV0319P.N 134 © Xsens Technologies B.V.
The information of use is in the panel on the right hand side. This data contains all of the data that was exported. To view data, select the data of choice e.g., joint angles from the list of parameters (sensors, segments, points, frames). Go to frames, joints angle and drag that label to e.g. Cell A1. A title box will appear. To view data, click refresh: It is clear that data is present, but it is still not defined. Document MV0319P.N 135 © Xsens Technologies B.V.
Document MV0319P.N 136 © Xsens Technologies B.V.
To work with the data, go to the data menu (Data Tab in Excel 2007). Select “Text to Columns”. The data is delimited. Document MV0319P.N 137 © Xsens Technologies B.V.
Using Tab and Space. The list of labels is also contained in the right panel, click and drag the parameter labels to the worksheet. See Section 12.5, for the details of the MVNX structure. Document MV0319P.N 138 © Xsens Technologies B.V.
22.1.2 Import to MATLAB Import MVNX files using the MATLAB files in the MATLAB Installer of MVN Studio. Below is a copy of the information stored in “main_mvnx.m”. This file intended simply as an example. The user is expected to expand upon this for their own use, depending on data they have exported to mvnx. The example code contains: main_mvnx.m and load_mvnx.m. The file main_mvnx is detailed below. It calls the function load_mvnx.m, which is based on the MATLAB function for reading XML files.
23 Synchronization with Third Party Devices 23.1 The Hardware MVN BIOMECH Awinda uses the Awinda Station for synchronization. From MVN Studio 4.1 and onwards, a Sync Station is provided with MVN BIOMECH for synchronization purposes. Details on initializing the synchronization of MVN are provided in Section 7.2.14. The purpose of this section is to provide some in-depth information about the synchronization possibilities.
23.2 Sync In Sync In means that a third party device sends a control signal to the Awinda Station. The Awinda Station can detect polarity changes on the input lines. This trigger may be a rising or falling edge as illustrated in the following figures: When a trigger is detected on one of the input lines, the Awinda Station can be configured to perform a certain action.
23.3 Sync Out Sync Out is the command that enables the Xsens system to send a trigger pulse for synchronization purposes. A control signal is sent via the Awinda/Sync Station, from MVN Studio to the third party hardware. Sync Type Description Start Recording Upon clicking the record button in MVN Studio, the Awinda Station starts the recording and consequently sends a start recording trigger to the third party system.
23.3.1 Settings in MVN Studio Once the spanner has been clicked, a new menu appears: Figure 70: Sync settings window in MVN Studio To add a synchronization type, click “Add”, all settings become available, to be set manually or using the drop down menus. Note that the Awinda/Sync Station can accept both rising and falling edges. The Pulse Polarity should be chosen depending on the requirements of the third party device.
frames since data received in a given frame is measured in the previous one. Therefore, delaying the recording in this way ensures that data is not recorded prior to the external trigger indication. In the same way, recording should not be stopped between frames, since data received in a given frame was measured during the previous frame. Therefore, the Awinda Station stops recording immediately after the current frame. 23.4.
23.7 Synchronization Examples 23.7.1 Start and stop recording of third party devices using single pulse Third party device starting and stopping recording of Xsens system, on Line 1 of the Sync In port.
Click “Add” Sync Type: Start Recording Sync Line: Out 1 Pulse Polarity: Rising Edge Pulse Width = 0µs12 Skip first = 0 Skip factor = 0 Trigger Once: Uncheck Click “Add” Sync Type: Stop Recording Sync Line: Out 1 Pulse Polarity: Falling Edge Pulse Width = 0µs[12] Skip first = 0 Skip factor = 0 Trigger Once: Uncheck Note: Stop recording time may not be on the last sample recorded. In any synchronization situation, there should only be one master.
23.7.3.1 Awinda Station Sends Sync Signal (Noraxon Receives Sync Signal) Hardware requirements: Noraxon Hardware Wireless EMG transmitters 1 TeleMyo DTS (plus antenna) Xsens Hardware MVN System Awinda Station Both systems of course also need related cables to connect to each other (with BNC connectors at each end) and a USB cable to connect to the PC. In addition to the normal MTw hardware setup, also connect the BNC connector from the TeleMyo DTS to Sync Out 1 on the Awinda Station.
Go to the drop down menu beside “When Channel”, select “Sync”; Select Rises Above (ensure that this is also the direction indicated on the mini-receiver); Input e.g. 0.5V Longer than 5ms Repeat settings for Stop Recording. Navigate further through the software. The Noraxon software initializes the EMG signals. When this screen is reached, click record, on the bottom left hand side of the screen on the Noraxon software. Document MV0319P.N 148 © Xsens Technologies B.V.
The software indicates that it is waiting for the trigger. Press Record in MVN Studio, and the Noraxon software indicates that recording has started. Repressing record in MVN Studio will stop the recording on both systems, where Noraxon will again indicate waiting for start trigger. 23.7.3.4 Awinda Station Receives Sync Signal (Noraxon Sends Sync Signal) For the Xsens system to send the synchronization commands, the mini-receiver from Noraxon is not needed. Document MV0319P.N 149 © Xsens Technologies B.
Hardware requirements: Noraxon Hardware Wireless EMG transmitters 1 TeleMyo DTS (plus antenna) 1 TeleMyo mini-receiver (plus antenna) Xsens Hardware MVN System Awinda Station Both systems of course also need related cables to connect to each other (with BNC connectors at each end) and a USB cable to connect to the PC. In addition to the normal MTw hardware setup, set up the hardware of the Noraxon system as follows: USB port of TeleMyo mini-receiver to USB of PC.
The rest of the software setup is as described in Section 23.7.3.6. However, instead of clicking Record in MVN Studio, press the hardware trigger from Noraxon to generate a manual trigger to both systems. 23.8 More Synchronization Examples Visit the Xsens website for synchronization examples of Xsens tried and tested with a number of third party hardware systems. While these examples are currently on the MTw page, the parameters have also been proven for MVN.
24 References i Wu G, Cavanagh PR (1995). ISB recommendations for standardization in the reporting of kinematic data. J. Biomech. 28: 1257-261 ii Wu G., Siegler, S., Allard, P., Kirtley, C., Leardini, A., Rosenbaum, D., Whittle, M., D’Lima, D., Cristofolini, L., Witte, H., Schmid, O., Stokes, I., (2002). ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion—part I: ankle, hip, and spine. J.
