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