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rotation angle measurement of pedal with ball and socket joint 4

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Mousa Saleh

Bioengineer
Dec 29, 2020
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Hi all,

I have a pedal with a ball and socket joint in its center.
the pedal is allowed to rotate in 3D.
I need to figure a way to measure the three angle rotations.

please help!
 
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the device that I have is the same as the mirror of this truck.

ball_and_socket_mcnlvj.jpg
 
The measurement needs a swash plate to extract the various components, which is the opposite of the typical function of a swash plate.
 
Here is one of many 3-axis angle (inclinometer) sensors:

I have used this sensor along with the free Android phone App. A PC app is also available. Hard to beat the small size, low weight, wireless Bluetooth, time history app, and very low cost! You need to understand/specify the required sensor resolution and accuracy and physical restraints. A calibration method is essential to verify and understand operation (sanity check). The Z-axis is typically has less resolution and accuracy.

Walt
 
Thank you very much walt,

This is what I was searching for.

If there is another better resolution inclinometer please provide me with its link and price is not a matter.

Mousa
 
Any time an axis aligns with gravity or is perpendicular to gravity then you will loose the ability to measure that axis with the 3-axis linear accelerometer.
 
What is the "zero" point for an electronic inclinometer? I can see gravity direction as one. Maybe the gyros set the other two? Maybe the "WITMOTION ADVANTAGE" compensates for it somehow.
 
Typically higher resolution inclinometers are one or two axis. Typically higher accuracy reduces angle range.

What are your specifications? The choices become limited as your specifications tighten!

Search: 3-axis precision inclinometer

WitMotion HWT905 High Precision 10-Axis Military-grade Inclinometer Sensor, Triaxial Gyro+Accelerometer+Angle+Magnetic+Quaternion Output, Built-in SCA3300 Temperature Compensation Chip, IP67 Waterproof: Amazon.com: Industrial & Scientific

AHRS Sensors | CS-AHxxx [CTi - Attitude and Heading Reference System] (ctisensors.com)

0729-1765-99 High Precision Digital Inclinometer Sensor - Fredericks (frederickscompany.com)

Digi-Pas 2-AXIS Precision Digital Inclination Sensor Module/Tilt Angle Sensor/Inclinometer/ DWL5000XY 0.002"/ft (0.2mm/M) NIST-Traceable (1. DWL5000XY) - - Amazon.com

The pasted Links did not show up, so search on your own.

Walt
 
The embedded MPU9250 has 3 gyros, 3 accels, and 3 magnetometers, so it can measure orientation irrespective of gravity. Much depends on how good the software processing is.

An alternative might be: marginally cheaper, and sans pretty case, but more insight into the innards.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
My specifications are:
range of 3d angles: +-60 degrees.
resolution: less that 0.25 degree for all axes.
I am really not sure what device to get form the dozen modules that I found,

I read the data sheet of wit-motion modules and fount that rotation angle might get affected by rotation of other axes.

Please help!
 
Yes there are a lot of sensor choices! You have not presented a detailed description of your project and sensor specifications.

Does your ball-socket joint really have an X/Y tilt of +/- 60-degrees and Z-axis rotation of +/- 60-degrees?

Measuring static or dynamic angles? Battery or AC/DC power? Wired or wireless connection? Data format: analog voltage or digital (RS232, RS485, TTL)? Measurement device: meter, analyzer, DAQ, cellphone, PC?

I suggest you make some preliminary measurements to assist with formulating specifications and a measurement plan. I used several tools before trying the Wit-motion sensor: spirit/bubble level, dial indicator, Clinometer App for Android (Samsung note 8), and "Number-one Digital Angle Gauge Level Box 2-in 1 Digital Protractor Inclinometer IP65 Waterproof Level and Angle Finder" (Amazon You could contact since they have a biomedical application and high speed sensors.

Walt
 
Dear Walt,

Thanks for your great help,

the ball and socket is able to rotate +/- 60 degrees in all directions.
I prefer AC/DC power, wireless connection, digital(TTL), and the measurement device is PC.

Thanks,

 
AC/DC power implies that sensor is wired; at least for power. Wireless connection implies that sensor is battery powered. Digital (TTL) implies wired connection; unless the wireless receiver connects to PC with a TTL interface. Obviously there are many combinations for sensor power and signal transfer.

Walt
 
I do not have experience with that company or product. The sensor specification for angles is not well defined for static values and it appears to be rated 1.0 degrees for dynamic values. It would be best for you to contact the sensor OEM instead of doing the design in this public forum.

Walt
 
I guess you would be choosing the SINC sensor from the three on the page. I suggest you get a trial or demonstration to see if it would fulfill your expectations and requirements. Sifting through a brochure and online manuals.

Walt
 
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