Center of Mass and Friction Coefficient Exploration of Unknown Object for a Robotic Grasping Manipulation

Center of mass (CoM) and friction coefficient (µ) are essential parameters in autonomous robotic manipulation system. However, it is difficult to measure these parameters. CoM is one of the internal properties, which depends on shape and mass distribution of the object. The parameter µ depends on the contact area between the object and robot finger. This paper provides an efficient method to calculate CoM and µ through three grasping manipulations. In the proposed method, a load cell is used to measure the gravity of the object, the omnidirectional slip sensor can obtain the object's rotation angle during the grasping manipulation, the robot can measure the grasping force. The method is applicable to unknown objects with irregular shape and uniformly-distributed mass. Besides, no prior knowledge of the object is needed. Experiments show that this method can accurately obtain position of CoM and the error is acceptable. The calculation of µ is more sensitive to error, but it still has significant values on object grasping manipulations.