CAN-based Network System for Speed Control of an Autonomous Vehicle

The work hereby presented deals with the partial automation of a utilitarian ground electric vehicle; in particular with the development and implementation of a Network Control System (NCS) using a Controller Area Network (CAN) based bus for speed control. This thesis highlights the use and development of standardized components and protocols in order to provide an easily upgradeable platform for future work, with enough robustness, reliability, and efficiency. A Programmable Automation Controller (PAC) is used to develop and execute the speed control algorithm, and eventually can act as a humanmachine interface via a personal computer. The kinematics involved are those of a rear-wheel differential driven conventional vehicle. An electric power controller is used to manage current and voltage flowing to/from the separately excited electric motor driving the vehicle. To develop the Network Control System based on the CAN protocol, CAN modules and additional specialized interfaces were manufactured, as well as CAN compliant cables and CAN hubs. A wheel speed sensor which functions as an incremental optical encoder was manually assembled in the Robotics Laboratory at the Tecnologico de Monterrey (ITESM). The CAN network is fully operational and has been tested proving to be a reliable channel for critical control information. The speed control algorithm is based on the proportional–integral–derivative (PID) controller model; tuning parameters were calculated and fine tuned via trial and error testing. Also, a fuzzy logic controller was developed to compare its performance against that of the PID. Three major distinctive phases involve this investigation; starting with the development and testing of the CAN network, followed by the programming of the speed controller algorithms and finally the integration of both into a complete Network Control System.