(Dr. Wayne Book, advisor)
"Implementations of a PD Controller on a Remote Axis Serial Interface Device"
Modern robotic systems are very complex, often employing numerous sensors, switches, and other electronic components in addition to the motors and amplifiers required for the motion. This complexity manifests itself in the wiring harness associated with the system. In industry, motion and supervisory control are generally provided at a common location which is not necessarily in close proximity to the robotic system, resulting in a bulky, failure-prone wiring harness. This thesis examines the development and implementation of a remote-axis serial-interface device (RASID) to locally control a single axis of a robotic system. The experimental RASID consists of a motor controller digital signal processor (DSP) and a Universal Serial Bus (USB) microcontroller with supervisory control provided by a PC.
The primary goal of the research was to develop a RASID which could receive a reference trajectory from the PC via the USB and perform PD (Proportional-plus-Derivative) control. The experimental system required a significant amount of software and firmware development, including a Windows application, a USB driver, USB firmware, and DSP firmware. DSP technology for digital motor control has improved to the point that very fast sampling rates can eb achieved. A known benefit of higher sampling rates is a reduction in the tracking error of a motion system. With the experimental RASID, sampling rates as high as 7 kHz were possible. Experiments were performed to observe and quantify the performance of the RASID. The performance characteristics of the experimental RASID, as well as the development of the software and firmware, are discussed in the thesis.