Grasp that optimises objectives along post-grasp trajectories

Abstract

In this article, we study the problem of selecting a grasp pose on the surface of an object to be manipulated by considering three post-grasp objectives. These objectives include (i) kinematic manipulation capability [1], [2], (ii) torque effort [3] and (iii) impact force in case of collision [4] during post-grasp manipulative actions. In these works [1]-[4], the main assumption is that a manipulation task, i.e. trajectory of the centre of mass (CoM) of an object is given. In addition, inertial properties of the object to be manipulated is known. For example, a robot needs to pick an object located at point A and place it at point B by moving it along a given path. Therefore, the problem to be solved is to find an initial grasp pose that yields the maximum kinematic manipulation capability, minimum joint effort and effective mass along a given post-grasp trajectories. However, these objectives may conflict in some cases making it impossible to obtain the best values for all of them. We perform a series of experiments to show how different objectives change as the grasping pose on an object alters. The experimental results presented in this paper illustrate that these objectives are conflicting for some desired post-grasp trajectories. This indicates that a detailed multi-objective optimisation is needed for properly addressing this problem in a future work.