Biomechanics Gait Analysis Lab - Biomedical Engineering ...

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3. Make sure that the sensor end of the FSR is in the middle of the grips, for even force application. 4. Set-up two speeds on the Tinius Olsen machine, speed 1 at 0.01 and speed 2 at 0.005 (see manual for Tinius Olsen machine to set-up speeds) 5. Hook up the insole to the transmitter telemetry device, attach probes from a digital multimeter to the output of the receiver box, and turn on both telemetry boxes. 6. On person starts speed 1, and calls out the force every 10 lbs starting at 40 lbs, while the other person writes down the output voltage reading. At 200 lbs select speed 2, and continue until 350 lbs is reached. 7. Turn all devices off when done From this data determine the FSR resistance value at each voltage reading, using the equations in Figure 39, and divide the resistance by 1 to get conductance. Using the conductance data and its matching force output, plot conductance vs. force in Excel and use linear regression to extrapolate the equation that will relate output force to conductance. Footswitch Insoles The footswitch insoles consist of four compression closing switches, at the heel, 1 st metatarsal, 5 th metatarsal, and toe, as shown in Figure 42. These switches act as an open or closed electric circuit, which requires an input of 5 volts. When pressure is applied to the switches, two rubber cylinders contact pieces of brass sheets on each side of the insole, which acts to close the electric circuit, as shown in Figure 43. The only information that this will provide is that pressure is being applied and the length of time that pressure is applied. This will not show variations in applied pressure. The footswitches can provide velocity, cadence, stride length, and information on gait cycle, single limb support, swing, and stance. The footswitches do not need to be calibrated, which is a difficult and lengthy process. The drive circuit for the footswitch insoles is simply a +9V battery connected to a voltage regulator to reduce the input voltage to +5V, which is shown in Figure 37. The footswitches are connected to the transmitter with a pulldown resistor in between. The pull-down resistor is need Page 50
to supply a very small voltage (less than 0.01V) because the transmitter cannot process no input and would send a default number which causes the program to give erroneous outputs. The pull down resistor set-up is shown in Figure 44. Fore Foot Width Great Toe 5 th Metatarsal 1st Metatarsal Great Toe Left Heel 1st Metatarsal 5th Metatarsal Footswitch Length Heel Width RightHeel Figure 42: Footswitch diagram Page 51
Page 1 and 2: Biomechanics Gait Analysis Lab Oper
Page 3 and 4: PARTS AND ACCESSORIES The following
Page 5 and 6: Table of Contents Section Page Numb
Page 7 and 8: The new laboratory utilizes a numbe
Page 9 and 10: Figure 4: FSR Insole The FSR’s ar
Page 11 and 12: Figure 8: Transmitter Box Figure 9:
Page 13 and 14: The receiver connects directly to t
Page 15 and 16: Figure 15:Footswitch Insoles LabVIE
Page 17 and 18: Figure 17: Men’s FSR Insoles LabV
Page 19 and 20: Figure 19:Womens FSR Insoles LabVIE
Page 21 and 22: 3. Place the fanny pack around the
Page 23 and 24: Figure 25: Footswitch Output Wire C
Page 25 and 26: 14. Press the OFF button on the blo
Page 27 and 28: Figure 30: Corrected Toe Sensor Dat
Page 29 and 30: 2. Place the transmitter box into t
Page 31 and 32: 8. Mark a start line on the floor w
Page 33 and 34: Battery Replacement 1. Turn both of
Page 35 and 36: 5. Place the 3v lithium battery in
Page 37 and 38: - Dry the cleaned area with a soft
Page 39 and 40: 3. Humidity The device should not b
Page 41 and 42: The footswitches and force sensitiv
Page 43 and 44: The sensors act as a force sensing
Page 45 and 46: 10-bit analog-to-digital conversion
Page 47 and 48: Figure 38: Microprocessor Circuit f
Page 49: Metric A L M S1 S2 mm. 9.5 35.0 25.
Page 53 and 54: A B C D Figure 45: Male LEMO Connec
Page 55 and 56: Telemetry: Transmitter Set-up Figur
Page 57 and 58: Figure 50: Receiver Circuit schemat
Page 59 and 60: The 418MHz transmitter/encoder chip
Page 61 and 62: Analog Inputs Digital Inputs Figure
Page 63 and 64: 4. Trouble-Shooting Problem Possibl
Page 65 and 66: 4- If no output coming out of the F
Page 67 and 68: 7. If the footswitches and the FSR'
Page 69 and 70: 10. If LabVIEW program is not worki
Page 71 and 72: 13. If the male LEMO connector is n
Page 73 and 74: 16. If LabVIEW program still not wo
Page 75 and 76: Page 75
Page 77: 20. If the circuit is working fine

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