A control system for SCARA robot is designed for implementing a robust dyna
mic control algorithm. This study focuses on the use of DSPs in the design
of joint controllers and interfaces in between the host controller and four
joint controllers and in between the joint controllers and four servo driv
es. The mechanical body of SCARA robot and the servo drives are selected fr
om the commercially available products. The four joint controllers, assigne
d to each joint separately, are combined into a common system through the m
other board hardwarewise and through the global memory softwarewise. The mo
ther board is designed to connect joint controllers onto the board through
the slots adopting PC/104 bus structures. The global memory stores the comm
on data which can be shared by joint controllers and used by the host compu
ter directly, and it virtually combines the whole system into one. To demon
strate the performance and efficiency of the system, a robust inverse dynam
ic algorithm is proposed and implemented for a faster and more precise cont
rol. The robust inverse dynamic algorithm is basically derived from an inve
rse dynamic algorithm and a PID compensator. Based upon the derived dynamic
equations of SCARA robot, the inverse dynamic algorithm is initially imple
mented with 1 msec of control cycle-0.3 msec is actually used for the contr
ol algorithm-in this system. The algorithm is found to be inadequate for th
e high speed and precision tasks due to inherent modelling errors and time-
varying factors. Therefore, a variable PID algorithm is combined with the i
nverse dynamic algorithm to reinforce robustness of control. Experimental d
ata using the proposed algorithm are presented and compared with the result
s obtained from the PID and the inverse dynamic algorithms.