Preliminary ISM330DHCX Tests

Inertial measurement units (IMUs) are pretty important for legged robots, as it provides a sense of orientation. However, to get quality readings, these sensors do not come cheap. I’ve used LORD MicroStrain and VECTORNAV products in some of our bigger robots, but these are not exactly economical choices when you want a robot that is supposed to be on the more affordable side. Then there’s the interesting product out of nowhere from none other than ST: ISM330DHCX.

So I had to grab one and see how it performs. To keep things simple on my end, I got Adafruit’s version, but I don’t imagine the actual sensor behaving differently because it is from them. I hooked it up to a Raspberry Pi via I2C and here are the results.

With Covid, it is difficult at the moment to get my hands on the MicroStrain and VECTORNAV that we have in the lab, but I’ll update this post later on with those two and see how this guy performs against them.

Gyro Rigidity and Drift

I am working with the Microstrain 3DM-GX3-25 and to better understand how to use it, I have also been studying the exact mechanism on how all its components work together. A part I found difficult as a novice engineer was how the gyro and the accelerometer work together. A key component of understanding the two’s collaboration is the drift that gyro experiences. This is a super short clip on YouTube that I found which sums up why the gyro is only good in the short run.