Help in choosing best approach for angular detection

[lau]

I would really like you to help me choose the best product (a compact and low power IMU) and algorithm to identify the angle with respect to a rotation axis (with 17cm radius and maximum angular speed 150rpm) while there are also other movements going on and if, to get a high accurate result, I need some other sensor to add to the system. In addition to suggestions, I was also wondering if anyone is available for a job collaboration to develop this project.

[FAE_CA1]

Hi,

Thanks for your inquiry.

You can use compact and low power BMI270 accel and gyro combo chip for your project to detect angular motion. BMI270 is 2.5 x 3.0 x 0.83mm LGA-14 package and consumes 685uA in normal mode with 1.6kHz sampling rate. You may enable BMI270 accel any-motion interrupt which is based on the slope acceleration data a(n) - a(n-1). When the slope goes beyond the threshold for how many samples, any-motion interrupt will be generated. You can then read BMI270 gyro data to confirm if it is true or not.

When there is an angular motion, the centripetal acceleration Ac = r * w^2, where r is the distance between the accel and the origin in the unit of m, and w is the angular speed in the unit of rad/s. When w is changing a little bit with r fixed, BMI270 accel slope will change as well.

Thanks.

[lau]

Thanks for the useful reply.

I still would like to have some details to understand what will be the outcome in terms of accuracy : is there some reliable literature or do you have an estimate of peak error (degrees of the planar rotation I am interested in finding).

Would it be better to implement a personalized algorithm or the embedded one? Other suggestions?

[FAE_CA1]

Hi,

Please let us know more information about your application and what kind of accuracy you want to achieve in your application. Then we can analyze if BMI270 can meet your requirement or not. If yes, then you need to develop and implement your own algorithm. If not, then you need to find out other solutions.

Thanks.

[lau]

Hi,

I need to calculate the angle of the crank of a bicycle rotating around the bottom bracket (its center of rotation) as the bycicle is traveling on the flat road with turns.

I would like to use an IMU located at the outer end of the crank  about 17cm long and considering that the maximum angular velocity is 150 RPM. The accuracy I wish to achieve is in the range of 1-2 degrees.