A scheme for controlling multimanipulator systems is presented. The control objective is to coordinate the manipulators to perform parts-matching tasks such as screwing a nut onto a bolt. The task of moving a rigid object can be treated as a special case. Two secondary control objectives, internal force control and load distribution, can be accomplished within the structure of the control law. The internal force control mechanism keeps the internal forces on the object being manipulated at a desirable level. The load distribution mechanism distributes control effort to each manipulator according to a weighting factor. It is also shown that the control algorithm has a modular structure which facilitates its implementation on a multiprocessor computer. The scheme was tested on a planar scara type dual-manipulator system. A series of experimental results is included to demonstrate the system performance under various conditions.>

The authors report experimental results of a scheme for controlling multiple manipulator systems. The control objective was to steer the payload to track a preplanned trajectory while controlling the interaction forces and the load distribution among the manipulators. The scheme was implemented on a planar SCARA-type dual-manipulator system. The hardware configuration of the experimental system is described. Experimental data are presented to demonstrate various aspects of the system performance including trajectory tracking control, load distribution, interaction force control, and robustness to model mismatch.>

The problem of dynamic control of a multifingered hand manipulating an object is considered, under the condition that some of the fingertips slide on the object surface. This work has many useful applications when considered in conjunction with work already done in the area of regrasping. In performing certain tasks with grasped objects, it is often necessary to change the contact locations of the fingers on the object. One method of achieving this is to break and remake the contacts; another method is to slide the fingertips on the object surface. This work provides a dynamic coordinated control scheme for a hand by which one can perform regrasping and reorientation of an object in the planar case.>

The authors consider the problem of grasp choice for an object held within a multifingered hand from the viewpoint of avoiding collisions between the manipulator links and the object during trajectory execution. A grasp planner is provided in the form of an algorithm that checks the feasibility of a given object trajectory and provides an envelope of feasible contact positions. During execution of the trajectory, contact positions of the fingertips on the object can be changed by sliding the fingertip along the object surface in a controlled manner. A dynamic control law that achieves this is presented and integrated with the grasp planner to determine a dynamic regrasping algorithm, which is illustrated by simulation.>

The author proposes a coordinated control law for a multimanipulator system performing parts-matching tasks. This control law enables the manipulators to perform the preplanned parts-matching maneuver while the entire parts-matching system is driven to follow a desired path. Manipulators are essentially treated as six-degree-of-freedom actuators with some nonlinear dynamics, which exert a set of contact forces on the object so that trajectory tracking is achieved and the desired internal force is realized. When the parts-matching system consists of only a single object, the control law degenerates to an expression that will drive a group of manipulators transporting a single object. A load-sharing scheme minimizes the weighted norm of the force applied to the object. In this way, a heavily weighted direction tends to get less load. This scheme does not require a force sensor. The author also discusses the choosing of the weighting factor and shows that the proposed control law can be implemented in a decentralized fashion.>

The authors provide a dynamic control law that guarantees the tracking of a given end-effector trajectory and also provides for the control of the redundant joint velocity. The desired redundant joint velocity can then be specified to optimize a cost function over the configurations allowed by the extra degrees of freedom that achieve the given end-effector position.>

Two problems in the study of multifingered robot hands are considered, namely grasp planning and the determination of coordinated control laws with point contact models. using the dual notions of grasp stability and manipulability, and a procedure previously developed for task modeling, the structure grasp quality measures are defined. These measures are then integrated to devise a grasp planning algorithm. Based on the assumption of point contact models, a computed-torque-like control algorithm is developed for the coordinated manipulation of a multifingered robot hand. This control algorithm, which takes into account both the dynamics of the object and the dynamics of the hand, is computationally effective and can be generalized to allow rolling motion of the object with respect to the fingertip.>

We present a new scheme for the adaptive control of mechanical manipulators along with proof of convergence. This work is an extension of our earlier work [Craig, Hsu and Sastry] [1]. The new scheme does not require the measurement of joint accelerations and needs less computation. We illustrate the theory with some simulations.

We present an adaptive version of the computed torque method for the control of manipulators with rigid links. The algorithun estimates parameters on-line which appear in the non-linear dynamic model of the manipulator, such as load and link mass parameters and friction parameters, and uses the latest estimates in the computed torque servo. We present what we believe is the first golbally convergent, rigorous proof of the stability of such a scheme in its non-linear setting, as well as its asymptotic properties and conditions for parameter convergence. We illustrate the theory with some simulation results.