DYNAMIC LOAD-CARRYING CAPACITY OF ROBOTIC MANIPULATORS WITH JOINT ELASTICITY IMPOSING ACCURACY CONSTRAINTS

A computational technique for obtaining maximum load carrying capacity for robotic manipulator with joint elasticity subject to accuracy and actuator constraints is described. The maximum loads carrying capacity which can be achieved by a manipulator during a given trajectory are limited by a number of factors. The dynamic properties of a manipulator, its actuator limitations, and joint elasticity (transmissions, reducers, and servo drive system) are probably the most important factors. This paper presents a strategy for determining dynamic load carrying capacity (DLCC) subject to both accuracy and actuator constraints where a series of cubical bounds centred at the desired trajectory is used in the end-effector oscillation constraint while a typical DC motor speed-torque characteristics curve is used in the actuator constraint. A general computational procedure for the multi-link case given arbitrary trajectory is laid out in detail. Finally, a numerical example involving a two-link manipulator with joint flexibility using the method is presented. In the simulation, the manipulator is required to follow a specified trajectory. The results obtained illustrate the tracking of the link reference trajectory and show the necessity of the dual constraints and indicate which constraint is more critical for a given robot and trajectory depending on the required tracking accuracy.