Estimation of inverse kinematics of arbitrary serial chain manipulators and human-like robotic hands

Abstract

Abstract-The general solution for inverse kinematics is a problem known for a long time. A lot of problems, algorithms, etc., depend on inverse kinematics. While solutions for specific serial or parallel chain manipulators exist, a good estimation for an arbitrary serial robot within a short computation time is still missing. We provide not only a tool for the discrete estimation of inverse kinematics of arbitrary serial chain manipulators, but also concepts for inverse kinematics optimization along entire paths (adaptive tunneling) and an approximation of a desired grasp with a human-like robotic hand (virtual shut grasp). The latter concept includes an efficient reduction technique of a complex, arbitrary hand, which enables a fast and accurate estimation of the inverse kinematics of an entire hand. In contrast to existing work, our approach is general, since it is neither restricted to certain configurations of the serial manipulator nor to specific structures of the hand. Moreover, our approach does neither rely on proximate starting positions nor does it require specific properties of the objective function concerning the position of the minima. It works even under the presence of multiple local minima in the solution space. Experiments show the performance of our system. The results of the estimation of the inverse kinematics are very accurate and the maximally required joint speeds along the paths are low. I. MOTIVATIONA robot which is supposed to reach a certain position with its end-effector needs to be moved to an appropriate configuration to place the end-effector in the desired position. In many situations, it is advantageous to have a system which takes the desired end-effector position as input and gives one, several or all possible goal configurations as output. The necessary mapping from the robot's workspace to its joint space is called inverse kinematics. The general solution of inverse kinematics is a known problem for a long time. Sometimes, the inverse kinematics can be computed explicitly for manipulators with certain structures. A general estimation framework for the inverse kinematics of an arbitrary serial robot is still missing. It can already be enough to know, whether a solution exits. In other cases, the knowledge about one, several or all solutions is desirable.We focus on the discrete analysis of the configurationspace. Such an analysis is, e.g., necessary for the evaluation of an arbitrary manipulator structure. We are interested in the inverse kinematics of an arbitrary serial chain manipulator at a given point without any incremental methods based on intermediate positions or (partial) derivatives (e.g., through The box should be transported. This means, first, that the object has to be grasped by the robotic hand (brown palm, magenta fingers). A serial chain manipulator has to put the hand into an appropriate position, such that a successful grasp is possible. Several configurations of the manipulator could be possible to reach a point (e.g., blue and red configurations of the...

Contact state based representation of object relations in the environment for dexterous manipulations

“…This way of estimating the inverse kinematics allows us the estimation of several alternative joint configuration sequences, since we are neither limited to pre-defined start configurations of the robot nor to possible local minima along the path. Further details can be found in [27].…”