Mechanical Structural Analysis and Design Optimization of Industrial Robots

Abstract

In an automated Flexible Machining Cell an Industrial Robot is required to carry out loading and offloading tasks and participate in off-line measurement. In these activities the robot speed, accuracy and compliance are the important performance measures. Improvement in speed reduces overall job time but this is generally achieved at the expense of accuracy. A further tradeoff is that of weight-lifting capability and accuracy. It is well known that commercial robot suppliers provide a range of machines in which accuracy is lost as speed is increased. This report summarizes some progress to date of basic research on the mechanical structural analysis and control of an industrial robot. The research is addressing this speed vs. accuracy vs. load capacity trade-off. To improve the robot performance a mathematical model of the robot dynamics is desirable. The model developed relates to a Trallfa robot but the results are applicable to other machines. The initial set of model equations are highly non -linear, time variant and coupled. Thus model reduction has been applied in which the gravitational fore components in each joint in the static mode have been separated out. In addition the base rotation has been developed from the rest of the system. The research results suggest that the third link should be heavily built to offset the gripper loading effect.