To enable the application of high-performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, a practical methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree-of-freedom Adept II robot, with pulsewidth modulation amplifiers and both variable reluctance and brushless DC motors, was converted to operate from joint torque commands to demonstrate the methodology. The average percentage torque derivation over the command and position ranges was reduced from as much as 76% to below 5% for the direct-drive joints 1, 2, and 4, and was reduced by more than 50% in the remaining ball-screw driven joint 3.>

The authors apply two Cartesian-space manipulator control algorithms, resolved motion rate (kinematics-based) and resolved acceleration (dynamics-based) control, to wheeled mobile robot (WMR) servo control. They evaluate simulation studies of two exemplary WMRs-Uranus, a three-degree-of-freedom WMR, and Bicsun-Bicas, a two-degree-of-freedom WMR-under the control of these algorithms. Although resolved-motion-rate servo control is adequate for the control of Uranus, resolved-acceleration servo control is required for the control of the mechanically simpler Bicsun-Bicas because it exhibits more dynamic coupling and nonlinearities.>

A formulation is introduced for the dynamic modeling of multibody robotic mechanisms to incorporate closed chains, higher pair joints, friction (including stiction, Coulomb, rolling and viscous friction), and unactuated and unsensed joints. Although this formulation was developed for the dynamic modeling of Uranus, and omnidirectional wheeled mobile robot, the methodology is directly applicable to a spectrum of multibody robotic mechanisms. The methodology is based on Newtonian dynamics, kinematics, and the concepts of force/torque propagation and frictional coupling at a joint introduced in this work. The extensible matrix-vector dynamics formulation allows the application of classical methodologies for the solution of systems of linear algebraic equations. To illustrate the procedure, the dynamics formulation is applied to a planar double pendulum and a biped in the frontal plane.>

We have introduced a methodology for the kinematic modeling of wheeled mobile robots. In this paper, we apply our methodology to Uranus, an omnidirectional wheeled mobile robot which is being developed in the Robotics Institute of Carnegie Mellon University. We assign coordinate systems to specify the transformation matrices and write the kinematic equations-of-motion. We illustrate the actuated inverse and sensed forward solutions; i.e., the calculation of actuator velocities from robot velocities and robot velocities from sensed wheel velocities. We apply the actuated inverse and sensed forward solutions to the kinematic control of Uranus by: calculating in real-time the robot position from shaft encoder readings (i.e., dead reckoning); formulating an algorithm to detect wheel slippage; and developing an algorithm for feedback control.