Design and Control of a Mounted Robotic Arm Tool Changer and Measurement Tools for Agriculture

Abstract

This thesis describes the design and manufacturing of a robotic arm tool changer system designed for an agricultural usage, built to be low cost, robust in its simplicity, and powered by actuators with high torque densities. Supporting a universal socket interface, the tool changer can swap between a broad array of instruments created for this project, including a thermal camera, an impedance analyzer, a pH probe, and near-infrared and visible light spectroscopes. Each of these tools are shown to have some application in the field, such as by measuring plant health or soil properties. However, with the variation of tools came the development of an autotuning library that could rapidly generate stable PID gains for a serial linkage with dynamics that are constantly expected to change with changes of endpoint mass. Combined with a custom-written trajectory optimizer, the process outlined by this PID autotuning library demonstrates a 40% improvement in root-mean-squared tracking error, a 14% improvement in average settling time, and a near 100% improvement in average percent overshoot compared to a untuned system with poorly selected gains.