The problem associated with planning a collision-free path for a wheeled mobile robot (WMR) moving among obstacles in the workspace is investigated in this paper. A kinematic model, including the general nonholonomic constraint equation, is developed first, followed by the analysis of some general maneuvering characteristics of the WMR. The analytic solutions to the typical path curves, such as circle and straight line, which are important in the path planning problem, are also derived. From the analysis of the established kinematic model, some factors which affect the path planning problem for a WMR and therefore must be taken into account are revealed and the general description of the path planning problem for a WMR is formuated. In conclusion, a possible architecture of the algorithm for a practical WMR is presented.

In this paper, a numerical approach is proposed to solve the time-optimal path-planning (TOPP) problem of kinematically redundant manipulators between two end-points. The first step is to transform the TOPP problem into a nonlinear programming problem by an iterative procedure. Then an approach to find the initial feasible solutions of the problem is proposed. Since initial feasible solutions can be found easily, the optimization process of the nonlinear programming problem can be started from different points to find the global minimum. A planar three-link robotic manipulator is used to illustrate the validity of the proposed approach.

A new method for computer forming of dynamic equations of open-chain mechanical robot configurations is presented. The algorithm used is of a numeric-iterative type, based on mathematical apparatus of screw theory, which has enabled elimination of the unnecessary computations in the process of dynamic model derivation. In addition to conventional kinematic schemes of robotic manipulators, the branched kinematic chains which have recently found their application in the locomotion of robotic mechanisms were also treated. Both the inverse and direct problems of dynamics were addressed. A comparative analysis was carried out of the numerical complexity of various existing algorithms of numeric-iterative type dealing with the problems of spatial active mechanisms dynamics. It has been shown that the proposed method regardless of its generality, approaches by its models complexity symbolic models, which are valid for particular robotic mechanisms only where they achieve a high degree of efficiency.

This paper presents an algorithm that solves the inverse kinematics problem of all six degrees of freedom manipulators, “general” or “special”. A manipulator is represented by a chain of characters that symbolizes the position of prismatic and revolute joints in the manipulator and the special geometry that may exist between its joint axes. One form of the loop closure equation is chosen and the Raghavan and Roth method is used to obtain symbolically a square matrix. The determinant of this matrix yields the characteristic polynomial of the manipulator in one of the kinematic variables. As an example of the use of this algorithm we present the solution to the inverse kinematics problem of the GMF Arc Mate welding manipulator. In spite of its geometry, this industrial manipulator has a non-trivial solution to its inverse kinematics problem.

This paper presents an absolute position estimation system for a mobile robot moving on a flat surface. In this system, a 3-D landmark with four coplanar points and a non-coplanar point is utilized to improve the accuracy of position estimation and to guide the robot during navigation. Applying theoretical analysis, we investigate the image sensitivity of the proposed 3-D landmark compared with the conventional 2-D landmark. In the camera calibration stage of the experiments, we employ a neural network as a computational tool. The neural network is trained from a set of learning data collected at various points around the mark so that the extrinsic and intrinsic parameters of the camera system can be resolved. The overall estimation algorithm from the mark identification to the position determination is implemented in a 32-bit personal computer with an image digitizer and an arithmetic accelerator. To demonstrate the effectiveness of the proposed 3-D landmark and the neural network-based calibration scheme, a series of navigation experiments were performed on a wheeled mobile robot (LCAR) in an indoor environment. The results show the feasibility of the position estimation system applicable to mobile robot's real-time navigation.

This paper presents a new approach for the design of variable structure control (VSC) of nonlinear systems. The approach is based on estimation of joint acceleration signals with introduction of load estimation with the asymptotic observer. The control system is insensitive to parameter variations for a chosen switching hypersurface in conditions when it is reached by the dynamic motion with the required dynamics. The parameter insensitive response provided by this control method is demonstrated on the model of the SCARA robot. Simulation results confirm the validity of accurate tracking capability and the robust performance.

A motion controller for an overhead Cartesian crane in three-dimensional Euclidean (3-D) space is designed under the constraint that the control action belong to a discrete set of assigned values. The design approach rests upon a two-step procedure: first, a constraintfree motion controller is determined that satisfies the required dynamic specifications; second, this controller is replaced with an equivalent controller satisfying the discrete action constraint. The first step is implemented by means of a heuristic 3-D extension of a well-proven 2-D controller, the second step by applying recent sliding mode results. Numerical simulations illustrate the properties of the resulting feedback system under both nominal and perturbed operating conditions.

This paper outlines the analysis methodology employed in the design of an anthropomorphic hand for the purposes of object handling by robotic manipulators, and for prosthetics. The final design is described and the safe handling of various objects using this anthropomorphic hand is discussed.

In a measurement system with intelligent, distributed sensor processes, complementary observations from different sensor need be combined with each other. This paper describes a method based on fuzzy measures, in which a global ‘fusion algorithm’ questions the sensors as to their support and opinion of a hypothesis. The sensor opinions are clustered into groups based on their support of each others' opinions, and fused using a new fuzzy operator.