|
Size: 4083
Comment:
|
Size: 4525
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 45: | Line 45: |
| 1. Acquire the appropriate sensor and Tekscan "dongle" for this test (decide on physical location and/or contact). 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. Acquire Tekscan sensor 5051 (Fig 1a) and Tekscan "dongle" (Fig 1b) for this test (decide on physical location and/or contact). The "dongle" is the harware interface between the sensor and a USB plugin for a computer. Make sure the computer has the latest Tekscan software installed (version ???). |
| Line 47: | Line 47: |
| 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. The foot pressure bladder hardware in the gait lab (ND1-07 behind the computers) will be used to evenly load the Tekscan sensor (Fig 1c). 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 (Fig 1d). 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 (Fig 1d). With the attached manometer (Fig 1d), verify the application of the maximum possible pressure (approximately 87 psi) and record the actual pressure and the sensor serial number. 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 to the repository in the folder structure for the specimen being tested. |
| Line 52: | Line 52: |
| 1. Once complete, save the sensor specific calibration file for future use. | 1. Once complete, save the sensor specific calibration file for use during calibration and testing. [[ImageLink(https://simtk.org/svn/openknee/doc/img/PressureBladder_Foot.png, width=700, alt=Experimentation Workflow)]] Figure 1. Pressure sensor in a joint (a), dongle attached to the sensor (b) and pressure bladder setup for equilibration of the Tekscan sensor (c and d). |
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 Tekscan sensor 5051 (Fig 1a) and Tekscan "dongle" (Fig 1b) for this test (decide on physical location and/or contact). The "dongle" is the harware interface between the sensor and a USB plugin for a computer. Make sure the computer has the latest Tekscan software installed (version ???).
- 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 (Fig 1c). 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 (Fig 1d). 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 (Fig 1d). With the attached manometer (Fig 1d), verify the application of the maximum possible pressure (approximately 87 psi) and record the actual pressure and the sensor serial number.
- 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 to the repository in the folder structure for the specimen being tested.
- 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 use during calibration and testing.
Figure 1. Pressure sensor in a joint (a), dongle attached to the sensor (b) and pressure bladder setup for equilibration of the Tekscan sensor (c and d).
Calibration
Primary Conditions
- Application of a known load of approximately 600 N to the sensor. Ideally, 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.