IEEE Transactions on Robotics and Automation

Manufacturing processes often produce a stream of parts that must be oriented precisely before assembly. Given the description of an n -sided planar polygonal part, K.Y. Goldberg (Ph.D. Diss., Carnegie-Mellon Univ., 1990) presents an O(n3 ) serial algorithm that produces an optimal sequence of gripper actions to orient the part up to symmetry using a sensorles... View full abstract»

A solution procedure for simulation dynamics of elastic multibody systems specifically designed for parallel processing is presented. The method is applicable to open chains with general (rotational and/or translational) interbody constraints. It is based on obtaining an explicit solution for the joint constraint forces by means of iterative techniques. Numerical results for a three-link anthropom... View full abstract»

A suboptimal trajectory planning problem for single-link flexible-joint robot arms is studied. A global feedback-linearization technique is first applied to reformulate the nonlinear constrained optimization as a suboptimal interpolation problem. Then the unique analytic suboptimal solution for the problem is obtained in closed form. Simulation results are given to show the effectiveness of the me... View full abstract»

A closed-form analytical solution to the problem of 3D estimation of circular-feature location is presented. Two different cases are considered: 3D orientation and position estimation when the radius is known and when it is not known. Extension of the method to general 3D quadratic features is also addressed. Simulated experimental results obtained for all three cases verified the analytical metho... View full abstract»

The calibration of manipulator kinematics subject to both geometric and nongeometric variations is addressed. A general definition of calibration is introduced, based on the concept of the group action. A specific calibration method is proposed, called calibration by diffeomorphisms. For calibration by diffeomorphisms, the existence of calibrating transformations has been shown to be equivalent to... View full abstract»

The problem of the optimal control of multiple-robot systems in the presence of obstacles is solved. All the robots are subject to state and control constraints. The method is based on nonlinear programming and decomposition coordination. The problem is solved by satisfying the constraints on the states and the controls as well as those on the obstacles. To generalize the problem, NR... View full abstract»

An inverse-dynamics-based method for discrete-time control of flexible-joint robots is presented. The main drawbacks of continuous-time analysis are its computational burden and the necessity for very high sampling frequencies. These inconveniences can be avoided by the use of numerical methods conceived for the solution of systems of differential-algebraic equations. Such an approach naturally le... View full abstract»

An efficient quantitative test for form closure valid for any number of contact points is formulated as a linear program, the optimal objective value of which provides a measure of how far a grasp is from losing form closure. When the grasp does not have form closure, manipulation planning requires a means for predicting the object's stability and instantaneous velocity, given the joint velocities... View full abstract»

Optimal performance of a manufacturing layout consisting of several mobile robots performing specific transportation tasks is addressed. A synergistic approach based on decentralized path planning, heuristic-algorithm-based navigation, and localized collision avoidance is presented. A comprehensive, flexible multiple mobile robots system (MMRS) consisting of standard patterns, a local controller, ... View full abstract»

The basic stability characteristics of the nonlinear hybrid control system are clarified by using Lyapunov's method in relation to autonomous systems. The fundamental stability condition of hybrid control is evaluated by using a hybrid control scheme, the friction effect, an additional phase lag (dead time), and the digital control effect. The sampling delay (dead time) causes a large additional p... View full abstract»

Collision-free multirobot motion planning can be achieved in two steps: path planning and trajectory planning. Path planning finds for the robots geometric paths to avoid collision with static obstacles and trajectory planning determines how fast each robot must move along its geometric path to avoid collision with other moving robots. For a dual-robot system, a simple trajectory planning strategy... View full abstract»

The position estimation problem for an autonomous land vehicle navigating in an unstructured mountainous terrain is solved. A digital elevation map (DEM) of the area is assumed to be given. It is also assumed that the robot is equipped with a camera that can be panned and tilted, a compass, and an altimeter. No recognizable landmarks are assumed to be present, and the robot is not assumed to have ... View full abstract»

A methodology for exact robot motion planning and control that unifies the purely kinematic path planning problem with the lower level feedback controller design is presented. Complete information about a freespace and goal is encoded in the form of a special artificial potential function, called a navigation function, that connects the kinematic planning problem with the dynamic execution problem... View full abstract»

A kinematic is presented that is fully parallel and actuator redundant. Actuator redundancy refers to the use of more actuators than are strictly necessary to control the mechanism without increasing the mobility. The uses of this form of redundancy include the ability to partially control the internal forces, increase the workspace, remove singularities, and augment the dexterity. Optimization ta... View full abstract»

Nonlinear feedback control for force-controlled robots with constrained end-effector motion is considered. A general method is presented that assures an exact feedback linearization for both rigid and flexible-joint robots, as the joint flexibility can cause instability of robot control. The feedback control linearizes and decouples the original nonlinear system into a number of decoupled linear s... View full abstract»

A model-based robot system is described. This system was developed to replace and improve upon the conventional robot control scheme of teaching-by-showing and replay. The key concept of this system consists of the combination of manipulation skills with an environment model. The model provides the geometric structure and the physical properties of the objects in the environment. Manipulation skil... View full abstract»

The kinematic singularities of robot manipulators are studied from the point of view of the theory of singularities. The notion of a `generic' kinematic map, whose singularities form smooth manifolds of prescribed dimension in the joint space of the manipulator, is examined. For three-joint robots, an equivalent algebraic condition for genericity using the Jacobian determinants is derived. This co... View full abstract»