Trigno/Vicon System Integration

Transcription

1 Delsys and Vicon Analog Integration Motion capture systems will often have the ability to sample analog data channels as a convenient means for synchronizing external data streams with motion capture data. This Technical Note provides specific instructions for interfacing the analog outputs of Trigno EMG systems with the data acquisition inputs of Vicon MX motion capture systems. Delsys Trigno Analog Outputs The Trigno System provides simultaneous analog signal reconstruction of data being detected by all active sensors. These signals are made available on the 68-pin connectors located on the Base Station. EMG signals at these outputs are amplified by a factor of 909, with full dynamic range of ±5V. Similarly accelerometer signals are presented with a nominal full range of ±5V. These must be calibrated according to their selected operational range (±1.5g, ±6g). Note that EMG signals exhibit a fixed 48ms delay from the time the sensor detects the event to the time the analog signal is reproduced. Similarly accelerometer signals exhibit a 96 ms delay. Refer to Technical Note TN304 for a detailed explanation of why this is so. Vicon motion capture systems, as with many others, offer screw terminal connections at the ADC (analog-todigital converter) inputs. Delsys can supply a cable assembly that mates with the Trigno Analog Output connectors and breaks out the individual channels onto single conductors (DC-A22 Unterminated Output Cable). Prior to making any connections ensure that the power is disconnected from both the Trigno and the Vicon systems. Figure 1 a) DC-A22 Unterminated Analog Output Cable. b) Trigno Base Station with analog connection cable. The pinout of this connector replicates the pinout of the Bagnoli desktop EMG systems to facilitate connectivity between shared equipment. Only EMG signals are provided on this connector. It is compatible with many National Instruments data acquisition modules and should not be used with the DC- ACC cable. This connector makes available all 64 analog output channels in the 68-pin connector and is to be used with the DC-A22 cable. This connector is compatible with some 80-channel data acquisition modules from National Instruments. Technical Note TN305 1

2 Take care when inserting the output cable to the Trigno Base Station, ensuring correct orientation and securing the connector thumbscrews. Do not connect the DC-A22 Analog Output Cable to the connector labelled EMG The DC-A22 should only be mated with the port labelled Vicon ADC Terminal Box The unterminated analog output cable from the Trigno Base Station should be inserted into the Vicon ADC screw terminal box. The individual wires should be screwed into the corresponding Vicon ADC terminal following the designated colour coding reference (See Delsys Trigno User Guide, P25 and App II). Pay careful attention to the screw terminal labelling, as incorrect connections may damage equipment. Connect all 4 Trigno Analog Ground wires to any 4 screw terminals labelled SGND. Do not connect these to the DGND terminals as these are reserved for digital signals. Cable Harness SGND CH22 Trigno Analog Signals Vicon System CH44 DGND Figure 2: Vicon ADC Terminal Box. The Trigno Analog Output Cable should be fed through the enclosure opening and secured with the cable harness once all connections are made. Pay careful attention the channel labelling as miswired connections may damage equipment. Technical Note TN305 2

3 Figure 3: a) Close-up of screw terminations. Ensure that the individual wires are tightly clamped in the terminals. Visually inspect the striped section wire prior to termination to ensure that it is intact. b) The assemble screw termination box once all conections have been made the cable secured in the harness. Inspect each individual conductor when installing to ensure that the wire is undamaged. Excessive bending over time and other mechanical stresses may fatigue the conductors causing them to weaken and eventually break. If this is the case, simply strip a section of insulation off the conductor (approx. 1 cm) to expose a fresh segment of wire. Once all cables are secured in the terminals and correspond to the correct colour references,proceed to fix the ADC housing lid and to connect the Vicon ADC connector. In order to operate the Delsys Trigno Base Station and configure the sensors, proceed with powering up the Trigno System, connecting the USB cable to the computer and following the software instructions below. Delsys Analog Output Software Included with the Delsys software package is the Trigno Analog Output software, which operates on a PC independently from EMGworks Data Acquisition and Analysis software. The Trigno Analog Output Software is designed to configure and control the Trigno System so that it becomes a full analog instrument. In this scenario, all data acquisition is performed by sampling the analog channels with 3rd party acquisition systems, in this case the Vicon system. The Trigno Analog Output application must remain running on the PC for the analog outputs to remain active. The wireless sensor configuration window is accessible from the configure button. Start and Stop controls activate and deactivate the analog outputs, and define the Start and Stop output trigger events. All settings are locked once the Start button is depressed, and can only be changed after the Stop button is pressed. Technical Note TN305 3

4 Figure 4: a) Starting the Trigno Analog Output Application. b) Trigno Control Utility. Simultaneous Data Collection (Vicon System & Delsys EMGworks) Collecting data using Delsys EMGworks Acquisition also allows the transmission of all 64 channels of analog data concurrently. Users are then able to take advantage of the advanced capabilities of Delsys EMGworks software as well as concurrently collecting synchronised motion capture with analog EMG. This may require the use of 2 PCs, one for managing the Vicon System and the other for managing EMGworks. Technical Note TN305 4

5 Vicon Nexus Software Setup Follow the brief instructions below to setup the Vicon Nexus Software to sample the Trigno analog signal outputs. 1. Place the Vicon Nexus into online status 2. After selecting Analog Card node, set the analog sampling frequency in the bottom properties window. EMG signal should be sampled at least at 1000 samples/sec (4000 Hz is preferred). Accelerometer signals should be sampled at least of 100 samples/sec (400 Hz is preferred). 3. Select Other Devices of system window and add analog EMG. 4. Select Source, find and select MX-Giganet to which the ADC terminal box is connected. Technical Note TN305 5

6 5. Select the Voltage node and then add components, depending on the number of channels used. 6. Determine a name for each channel, selecting the pin number and the gain. (This information will be exported within the ASCII data. The hardware and software should now be configured so that the Vicon Motion Capture system will sampled the designed analog channels outputted from the Trigno EMG System. Please refer to relevant user manuals for further information on particular aspects. Technical Note TN305 6