Challenges in Measuring Joint Angles Using IMUs

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
Hi everyone,

I just wanted to ask if it is possible to measure body joint angles using an IMU based system e.g placing an IMU on the lower part of leg and one on the upper part to measure the knee angles. What could be the challenges in implementing this, like sensor alignment etc and what kind of accuracy should one expect.

Regards.
 

bug13

Joined Feb 13, 2012
2,002
Using Karman filter, I believe you can get pretty good result. The hard part (for me) is to get the accurate mode for the system if you want very high accuracy.
 

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
Using Karman filter, I believe you can get pretty good result. The hard part (for me) is to get the accurate mode for the system if you want very high accuracy.
Thanks for the reply. Would it be accurate up to let's say one degree. Also there is another thing confusing me that when connecting 2 IMUs to a single i2c bus of the microcontroller I would first read one IMU and then the other, is there a possibility of phase shift between the two readings.
 

bug13

Joined Feb 13, 2012
2,002
Thanks for the reply. Would it be accurate up to let's say one degree. Also there is another thing confusing me that when connecting 2 IMUs to a single i2c bus of the microcontroller I would first read one IMU and then the other, is there a possibility of phase shift between the two readings.
I haven't done any test on the accurate, but from what I read, 1 degree should not be hard to achieve. Beside you can always add extra sensors to increase the accuracy. (eg magnetic senor, some IMU comes with these).

It depends on how fast the angle change and the update rates of your IMU, it really depends on your application. Karman filter can possible fix you phase shift problem.
 
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