Encoder-free odometric system for autonomous microrobots

This paper describes an odometric system for autonomous microrobots based on the optical properties of a motor–wheel transmission for motion feedback. We demonstrate that infra-red light, reflected from this mechanical system, shows distinctive periodic changes of amplitude, correlated with the motion of the robot. Real-time odometric signal processing, performed on a small embedded microcontroller, allows accurate movement detection for each wheel and is used for motion control, self-calibration, and calculation of differential and absolute velocity, displacement and rotation. We demonstrate some applications of this on-board odometric system in swarm robot experiments. This approach can also be applied to other industrial or academic mechatronic systems, where size or computational power are limiting factors.