Page 674 - The Mechatronics Handbook

FIGURE 21.15 Servo system with PD-controller.

FIGURE 21.16 Responses of the system of Fig. 21.16.

FIGURE 21.17 Bode plots of type RA and AR systems.

Design of a Mobile Robot

A typical example of the early design procedure is the conceptual design of a mobile assembly robot.
Already in a very early stage of the design conflicting demands have to be resolved. Such a robot should
be able to collect parts all around a production facility and do the assembly while driving. Because a
high accuracy is required between the gripper of the robot and the surface where the parts are located,
it is important that floor irregularities and vibration modes of the structure do not prevent proper
assembly. On the other hand the path controller, partly based on dead reckoning (i.e., measuring of the
wheel speed and orientation), requires that the wheels be very stiff. Damping of disturbances has to be
realized by another means of suspension. This has led to the concept of an upper frame and a lower
frame, connected by means of springs (Fig. 21.18).

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