Arduino

I use a ton of different types. I think my favorite is the EM deflection sensor, which is normally advertised as a "microwave radar" (it's not really either) sensor:

https://www.aliexpress.us/item/2251832601397384.html

The output is binary so it's easy to wire up. The sensor works through non-metallic surfaces so I can put it inside work boxes and still detect movement nearby. It's really fun to make Halloween jump scares with it since it can be totally invisible to people.

I'm currently starting to use LiDAR sensors. It's more work to do the background subtraction, clustering, and interpretation, but it's coming together. I want to make skeleton heads on servos that track people coming up my walkway.

For now, I'm working with Slamtec's RPlidar A1. It's cheap, does 360 degrees, and has basic libraries available: https://www.slamtec.com/en/Lidar/A1/

I’ve been working on a project of a digital bubble level with gyro stabilization. I’ve done some fairly intensive testing with different gyro/accelerometer combo systems. Of of the lot, the BNO085 really stands out because it’s the only one (apart from the BNO055, which is the previous version) that does the fusion of the two sensors internally and output a AHRS (angle of the sensor position in the world) without manually implementing a complicated algorithm library (out of all the libraries I tried, the Fusion aka Madgwick2 was the best but still a real pain to implement). It’s designed for VR/AR headsets and gaming, the down side is that the whole match is black boxed so it’s harder to troubleshoot if needed.

Probably IMUs.. don’t know why