Synthesis of Robot Dynamic Control

As we have explained in previous chapter, during simultaneous motions of robot joints there appear dynamic forces (torques) which act around the joints axes and affect the performances of local servo systems. To ensure accurate tracking of nominal trajectories (imposed by the higher tactical control level) we have to compensate for the effects of these dynamic forces. If the executive control level has to ensure only positioning of the robot hand in various positions in work space, or to ensure tracking of “slow” trajectories of the robot hand, then the effects of these dynamic forces might be relatively weak and they might be ignored. Therefore, the local servos might accomplish such control tasks. In the previous chapter we have shown how we can examine whether or not the local servos could ensure accurate tracking of desired trajectories. If local servo systems can not “overcome” the effects of dynamic forces, we must introduce additional control loops which take into account these dynamic forces. Such control law, which accounts for dynamic characteristics of robotic systems is called dynamic control of robots.