Abstract:
A new approach to tracking control of industrial robot manipulators is presented in this paper. The highly
coupled nonlinear dynamics of a six degrees of freedom (6-DOF) serial robot is decoupled by expressing
its variables as a function of a flat output and a finite number of its derivatives. Hence the derivation of the
flat output for the 6-DOF robot is presented. With the flat output, trajectories for each of the generalized
coordinates are easily designed and open loop control is made possible. Using MATLAB/Simulink Sfunctions
combined with the differential flatness property of the robot, trajectory tracking is carried out
in closed loop by using a linear flat controller. The merit of this approach reduces the computational
complexity of the robot dynamics by allowing online computation of a high order system at a lower
computational cost. Using the same processor, the run time for tracking arbitrary trajectories is reduced
significantly to about 10 s as compared to 30 min in the original study (Hoifodt, 2011). The design is taken
further by including a Jacobian transformation for tracking of trajectories in cartesian space. Simulations
using the ABB IRB140 industrial robot with full dynamics are used to validate the study.
