This paper addresses the development, implementation, and evaluation of a novel application of robot force control called position based force scaling. We report the first results in the implementation of asymptotically exact force scaling, as well as the first results in on-line environment compliance adaptation while performing the task of force scaling. One previously reported and two new (one adaptive and one non-adaptive) force scaling algorithms are reviewed. Extensive comparative experiments quantify the performance of all three algorithms and show that the new adaptive force scaling algorithm significantly outperforms both its non-adaptive counterpart as well as the previously reported set-point-regulator based force scaling algorithm over a wide range of user applied input force trajectories and force scale factors.

This paper addresses the problem of achieving exact dynamic force control with manipulators possessing low-level position and/or velocity controllers typically employed in industrial robot arms. Previously reported approaches and experimental results are reviewed. A new adaptive force control algorithm for velocity/position controlled robot arms in contact with surfaces of unknown linear compliance is reported. The controller provably guarantees global asymptotic convergence of force trajectory tracking errors to zero when the robot is under exact or asymptotically exact inner loop velocity control. An additional result which guarantees arbitrarily small force errors for bounded inner loop velocity tracking errors is presented. Comparative experiments show the new adaptive velocity (position) based controller and its nonadaptive counterpart to provide performance superior to that of previously reported position-based force controllers.

This paper addresses the problem of achieving exact dynamic force control with manipulators possessing the low level position and/or velocity controllers typically employed in industrial robot arms. Previously reported approaches and experimental results are reviewed. A new adaptive force control algorithm for velocity/position controlled robot arms in contact with surfaces of unknown linear compliance is reported. The controller provably guarantees global asymptotic convergence of force trajectory tracking errors to zero when the robot is under exact or asymptotically exact inner loop velocity control. An additional result which guarantees arbitrarily small force errors for bounded inner loop velocity tracking errors is presented. Comparative experiments show the new adaptive velocity (position) based controller and its non-adaptive counterpart to provide performance superior to that of previously reported position based force controllers.

This paper reports the mechanical design, structural analysis, and experimental verification of a new high performance semi-direct drive robot arm. A design optimization methodology employing finite element analysis (FEA) is reviewed, and a resulting arm design is reported. FEA simulations of the final design predict high structural vibration frequencies throughout the arm workspace. Extensive structural vibration experiments with the completed manipulator confirm the predicted structural vibration characteristics throughout the arm workspace.

This paper reports the structural design of a new high-performance robot arm. Design objectives for the new arm include large (1-2m) workspace, low weight, 5 kg payload capacity, high stiffness, high structural vibration frequencies, precise joint-level torque control, a total of three degrees-of-freedom, and mechanical simplicity. A comparative analysis is reported for four very different two degree-of-freedom linkage candidates using the finite element method.