Motion Detector Sensor Troubleshooting and FAQs

Motion Detector, order code MD-BTD, $79
Specifications and User Guide

There are two Motion Sensor models:
Motion Detector 1 (MDO-BTD) - blue plastic, two LEDs below and to the left/right of the gold screen.
Motion Detector 2 (MD-BTD) - green plastic, one LED on the right below the gold screen, track mode switch inside pivoting head. (Began shipping 1/2005.)

TROUBLESHOOTING

- Test 1: Does a green LED light up after it is plugged-in and autoID'd by a data-collection program?
- Test 2: When you start data collection, do you hear a clicking from the Motion Detector? If not, the sensor may be defective.
- Test 3: Lay the Motion Detector on its back and point it straight up in the air. Hold your hand about 80 cm above the Motion Detector. Start data collection and slowly move your hand up and down approximately 10 cm above and below the 80 cm position. Does the sensor pick up the motion of the hand? If so, the sensor is probably fine and the problem may be the experimental setup.
- Test 4: Motion Detectors use ultrasound to measure position. Other sources of ultrasound may be interfering with the signal. Those sources include air tracks, CRT computer monitors, fluorescent lights, and power distribution panels. Identifying these sources can be challenging. You may have to resort to moving the motion detector away from interfering equipment. In the case of noisy fluorescent lights, turn them off, but we rarely see this problem.

- Tip 1: The optimum collection rate is 20 pts/second.
- Tip 2: Clear all objects within the 30 degree cone.
- Tip 3: If you are monitoring the motion of objects on a table or track, tilt the head up slightly.
- Tip 4: Use the Track mode switch when using a cart on track. Use Normal mode for all other applications. It does no harm to try the other mode.
- Tip 5: Increase target's area.
- Tip 6: Noisy velocity data: increase the number of points used for derivative calculations. See TIL 2331: How do I adjust the number of points used in derivative calculations?
- Tip 7: The maximum sample rate that you can use for the motion detector is 50 Hz, which equates to a sample interval of 0.02 seconds. We do not recommend that setting as it tends to produce noisy data.

RELATED TIL ENTRIES

TIL 5: Why am I getting Motion Detector readings that are noisy or max out at a certain distance?
TIL 19: Can I use 2 motion detectors with my Vernier Interface?
TIL 410: Can you create new match files for Logger Pro?
TIL 405: Can I use a PASCO motion detector with the LabQuest, LabPro, CBL, or ULI interfaces?
TIL 649: How do I calibrate a MPLI Motion Detector?
TIL 459: What don't I get a freefall acceleration value of 9.8 m/s^2 when using a motion detector?
TIL 318: Should I get a Motion Detector or a CBR?
TIL 1009: Why are LabPro Motion Detector distances in Logger Pro sometimes offset by 1 meter?
TIL 1001: How do you create new match files for MacMotion or Motion?
TIL 1205: My Motion Detector is not collecting data with DataMate and LabPro.
TIL 1914: My motion detector still reads 0.004 m after zeroing.
TIL 1938: Should I use a photogate or a Motion Detector?
TIL 2053: How do I improve the results from a Motion Detector with an air track?
TIL 2120: How can I collect data from a photogate and a motion detector data at the same time in Logger Pro?
TIL 1011: How does Logger Pro calculate velocity and acceleration from Motion Detector data?

SPECIFICATIONS

- order code: MD-BTD
- ultrasound frequency: 50 kHz
- resolution: 1 mm
- accuracy: 2 mm
- range: MD-BTD - 0.15 m to 6 m
MDO-BTD - 0.5 m to 6 m
- speed of ultrasound used to calculate distance: 343 m/s *
- power: 51 mA while running

*Adjusting the "temperature" setting in Logger Pro changes this value. Speed increases with temperature. We apply a linear correction such that a 1°C change of temperature is equal to 60 cm/s change of speed of sound. The Go! Motion is more sophisticated because only it has a built-in temperature sensor and applies the correction automatically.

CALIBRATION

- Air temperature corrections are possible only in Logger Pro and Logger Lite in the Sensors dialog.

RELATED VERNIER PRODUCTS

- Motion Detector Clamp, order code MD-CLAMP, $7, order separately
- Motion Detector to LabQuest/LabPro/CBL Cable, order code MDC-BTD, $5, shipped with sensor
- Cable Motion Detector to MPLI, order code M-MDC, \Contact Us
- Cable Motion Detector to ULI, order code ULI-MDC, $5
- Motion Detector Bracket, order code MDB-VDS, $11
- Digital Extension Cable, order code EXT-BTD, $12, 2 m in length