Automatic generation of forward and inverse kinematics for a reconfigurable modular manipulator system

AbstractTraditional industrial and research manipulators have a fixed configuration and are thus suited for a certain class of tasks. In order to make manipulators flexible and suited for a larger class of tasks we have proposed the concept of a Reconfigurable Modular Manipulator System (RMMS). The RMMS consists of a set of modular links and joints of various sizes; reconfigurable manipulators are designed and built from this system as appropriate for a given task. In order to effectively utilize such a system, one needs algorithms for automatically generating the kinematic descriptions for an arbitrary manipulator configured from the RMMS. Previous research on the kinematics of robotic manipulators has addressed fixed configuration manipulator systems. In this article, we propose an algorithm for automatically generating both the forward and inverse kinematics of a serial linkNdegrees‐of‐freedom reconfigurable manipulator. Generation of the kinematic equations that govern a modular manipulator starts with geometric descriptions of the units, or modules, as well as their sequence in the manipulator. Using this geometric information, we determine the Denavit‐Hartenberg parameters of a reconfigurable manipulator. The Denavit‐Hartenberg kinematic parameters are then used to obtain the forward kinematic transformation of the system. We also address the problem of otaining the inverse kinematics of reconfigurable manipulators. In order to automate the inverse kinematics and to make the procedure as general as possible, we have proposed the idea of scaling a manipulator. We use the efficient numerical approach and in the case of a redundant manipulator, we exploit the extra degrees of freedom to achieve singularity avoidance. We have implemented our algorithms on an Ironies 68020 based single board computer that is used to control the prototype Reconfigurable Modular Manipular System (RMMS) which is being developed in our laboratory.