Design of Low-Level Hardware for a Multi-Layered Control Architecture

In this work, the low-level (LL) hardware for sensor collection, motor input, and networking with a high-level (HL) controller is presented for robot systems which utilize linear series elastic actuators (LSEAs) for joint actuation. In multi-joint robotic systems, LL controllers rely on sensor readings to control each joint and communicate the obtained information to the HL controller. This research outlines the hardware design of two printed circuit boards (PCBs), as well as the use of an EasyCAT PRO board for communication. An in-house sensor interface shield is designed as an extension of the TM4C123GXL TIVA microcontroller launchpad and another in-house shield connects to the AZBDC12A8 analog servo drive, or rather, the motor controller. These PCBs allow for sensor integration with circuits that route, filter, or manipulate data obtained from the sensors. The goal of the sensor interface shield is to interface between sensors and the microcontroller. The sensor board takes readings from a force sensor, absolute encoder, quadrature encoder, as well as adjusting the pulse-width modulation (PWM) signal that is sent to the motors. The main purpose of the motor shield is to supply power, route the PWM input, and filter the current output of the motor. The final designs for both the shields are built in the PCB design software Eagle. Overall, these boards will allow for better sensor integration for LL controllers which interface with LSEA driven multi-joint robotic systems.