A New Energy-free Gravity-compensation Adaptive System for Balancing of 4-DOF Robot Manipulators with Variable Payloads

In most of gravity balancing approaches devoted to robot manipulators, the gravity compensation is carried out for cancelling of the static efforts due to robot element masses, as well as a fixed payload. When the payload is variable, i.e. if for each cycle of the robot operation it is different, the known compensation techniques are not efficient. Some solutions permitting to compensate the gravity effects of variable payloads have been developed. However, they have similar drawbacks. To adapt the robot to the changing payload it is necessary: i) to increase the number of actuators and ii) to bring energy inside the system, i.e. the adaption technique is not energy efficient. This paper deals with a new gravity-compensation system for cancellation of the static loads of the changing payload. It is shown that the adaption to a new manipulated payload does not need to bring energy inside the system, i.e. the adaption technique is energy efficient. Simulations of the suggested mechanism by using ADAMS software are performed and show the efficiency of the proposed solution.