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* | * Equivalent loading on all sensels |
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* A Tekscan defined, sensor specific, equivalencing file | |
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1. Acquire the appropriate sensor and Tekscan "dongle" for this test. The current sensor of choice is Tekscan model number 5051. The dongle is the harware interface between the sensor and a USB plugin for a computer (picture). 1. After plugging in the hardware to both the sensor and a computer, ensure the sensor is communicating with the Tekscan software. Physically squeeze the sensor to verify in the real time window of the Tekscan software that the sensels respond to the load. 1. The foot pressure bladder hardware in the gait lab (ND1-07 behind the computers) will be used to evenly load the Tekscan sensor. Check the operating oil in the compressor (Jun-Air) before plugging it in, turning it on and waiting for the tank to pressurize. Once ready, load the sensor on the pull out tray of the pressure bladder (picture). Place the sensor approximately in the middle of the tray. Slide the tray into the slot while ensuring the sensor does not bind. 1. Once the sensor is loaded, open the valve on top of the pressure bladder to load the sensor. With the attached manometer, verify the application of the maximum possible pressure (approximately 87 psi) and record the actual pressure. 1. Verify the sensor is loaded in the real time window of the Tekscan software and then perform the "calibration" procedure in the drop down menu. Fill in the appropriate fields and save the calibration file in a known location. 1. Close the valve on the pressure bladder and bleed the pressure from the system. Verify the load has been removed from the sensor in the real time window. Apply the sensor-specific calibration file to the sensor. Close the bleed valve. 1. To verify the calibration has been applied, reload the sensor with the pressure bladder. Verify the sensor reads an equivalent pressure across each sensel. If not, verify the calibration file is applied and/or repeat the steps above. 1. Once complete, save the sensor specific calibration file for future use. |
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* | * A Known load of approximately 600 N applied to the sensor. The sensor should be loaded using items of similar stiffness and geometry as a patellofemoral joint. |
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=== Notes === |
Target Outcome
- For use during patellofemoral joint testing, two properly equivalenced and calibrated pressure sensors.
Prerequisites
- A proper size and range sensor
- An operating Tekscan handle (interface to the sensor) and software
Infrastructure
For more details see ["Infrastructure/ExperimentationMechanics"].
Prerequisite Protocols
- ["Specifications/Specimens"].
- ["Specifications/SpecimenPreparation"]
- ["Specifications/Registration"]
- ["Specifications/ExperimentationAnatomicalImaging"]
Protocols
Sensel Equivalencing
Primary Conditions
- Equivalent loading on all sensels
Secondary Conditions
N/A
Measurements
- Sensor output in raw format
- A Tekscan defined, sensor specific, equivalencing file
Operating Procedure
- Acquire the appropriate sensor and Tekscan "dongle" for this test. The current sensor of choice is Tekscan model number 5051. The dongle is the harware interface between the sensor and a USB plugin for a computer (picture).
- After plugging in the hardware to both the sensor and a computer, ensure the sensor is communicating with the Tekscan software. Physically squeeze the sensor to verify in the real time window of the Tekscan software that the sensels respond to the load.
- The foot pressure bladder hardware in the gait lab (ND1-07 behind the computers) will be used to evenly load the Tekscan sensor. Check the operating oil in the compressor (Jun-Air) before plugging it in, turning it on and waiting for the tank to pressurize. Once ready, load the sensor on the pull out tray of the pressure bladder (picture). Place the sensor approximately in the middle of the tray. Slide the tray into the slot while ensuring the sensor does not bind.
- Once the sensor is loaded, open the valve on top of the pressure bladder to load the sensor. With the attached manometer, verify the application of the maximum possible pressure (approximately 87 psi) and record the actual pressure.
- Verify the sensor is loaded in the real time window of the Tekscan software and then perform the "calibration" procedure in the drop down menu. Fill in the appropriate fields and save the calibration file in a known location.
- Close the valve on the pressure bladder and bleed the pressure from the system. Verify the load has been removed from the sensor in the real time window. Apply the sensor-specific calibration file to the sensor. Close the bleed valve.
- To verify the calibration has been applied, reload the sensor with the pressure bladder. Verify the sensor reads an equivalent pressure across each sensel. If not, verify the calibration file is applied and/or repeat the steps above.
- Once complete, save the sensor specific calibration file for future use.
Calibration
Primary Conditions
- A Known load of approximately 600 N applied to the sensor. The sensor should be loaded using items of similar stiffness and geometry as a patellofemoral joint.
Secondary Conditions
N/A
Measurements
- Sensor output in raw format
Operating Procedure
- The Tekscan provided "power law" calibration approach has been shown to the within 2.7% RMS over the tested sensor range
Refer to http://www.ncbi.nlm.nih.gov/pubmed/19154074 for a description.
- A custom approach to calibration is likely more accurate and could be explored if necessary.
-- ["hallorj"] DateTime(2013-11-04T21:58:44Z) An email will be sent to Tekscan to find out the cost for current software as well as sensor pricing. I will also ask about their fixtures for equivalencing (this has proven challenging in the past).
-- ["hallorj"] DateTime(2013-11-11T17:32:36Z) An email was sent to Tekscan. I will update the specifications once we have more information.