Control system for designed mobile robot - Project, implementation, and tests

Abstract

The solution ofmobile robot control presented in the paper fulfilled the constructors? assumptions. One chosen test was presented The realization of positioning and velocity control tasks turned out to be effective. A set of elementary control tasks have been implemented, each of which can only be accomplished executing the proper command. The command can be sent only by the on-board computer (Fig. 37.3). The fast communication network works in real time. The CAN bus keeps up with the rate the control commands are being transmitted thanks to one of its properties ? relatively small number of data packed in one message. For example, using CAN itrate of 250 kb/s, the frequency of the control loop equals ca. 450 Hz (assuming that 5 111-bit frames are transmitted every cycle). Our system works with CAN bitrate of 250 kb/s. It is sufficient in the case of position or speed steering. During the project realization a set of dedicated tools were used e.g. CANopenTM profiles, IQMath library for precise fixed-point arithmetics using the DSP. The open communication system makes it possible to use additional on-board executive elements, as long as they are equipped with a CAN interface and a suitable modification of the on-board controller software is made. The extension is also possible in the range of environment contact sensors as well as different measuring systems. Nonholonomic constraints that rule the rights of robot movement are taken into account in this paper. The authors do not consider longitudinal constraints though, ecause the projected dynamics of movement was not large. In the future, these constraints we will be taken under consideration. One can see easily in the presented results that the amplitudes of the desired velocity signals are larger than the executed signals ? it is the result of drive settings. © 2009 Springer-Verlag London.