Two strategies for handling unknown loads of two coordinating robots

In real situations, a robotic system can work in an unstructured environment in which the load is often unknown. This problem is an under-studied one, especially for multi-robot systems. In this paper we solve this problem by the ‘Unknown Load Distribution’ method for two coordinated industrial robots Two methods are proposed for the distribution of an unknown load. The first method is called “load estimated method’, in which the parameters associated with the load are estimated using the information provided by two wrist force sensors. As a result, the load becomes known, and conventional optimal load distribution methods can then be applied to distribute the force. The second method is called the ‘force compensation method’, in which one of the robots (the leader) takes the major role of carrying the load to the exact location and the other robot (the follower) follows the leader with a specified force. The load is compensated by the follower using force control until the leader can carry the load to follow a satisfactory trajectory. To verify the force compensation method, a computer simulation is conducted.