In this paper, we develop a method for mobile robot control using ultrasonic sensors to determine displacement constraints between two parallel planes. Robot control has been simulated for this situation. Results obtained by simulation and experimentation are presented. A degraded mode which considers the use of one valid ultrasonic sensor is studied. In this case, a new model is developed and new results are analyzed.

A prototype system utilizing a vision technique to monitor the parameters of adhesive beads or sealants is presented. The system uses a structured light technique to investigate adhesive beads and extract information about the shape of the bead from binary images. The geometrical model of the bead, the relationship between this model and the shape of a line of light on the image are investigated. The models for calculating the parameters of the bead and the height of the camera are analyzed. Control strategies are suggested.

Interpolation of a robot joint trajectory is realized using trigonometric splines. This original application has several advantages over existing methods (e.g. those using algebraic splines). For example, the computational expense is lower, more constraints can be imposed on the trajectory, obstacle avoidance can be implemented in real time, and smoother trajectories are obtained. Some of the spline parameters can be chosen to minimize an objective function (e.g. minimum jerk or minimum energy). If jerk is minimized, the optimization has a closed form solution. This paper introduces a trajectory interpolation algorithm, discusses a method for path optimization, and includes examples.

An iterative learning control method is proposed for a class of non-linear dynamic systems with uncertain parameters. The method, in which non-linear system model is used, employs the model algorithmic control concept in the iteration sequence. A sufficient condition for convergency is provided. Then the method is shown to be applicable to continuous-path control of a robot manipulator.

A new approach to motion planning for multiple robots with multi-mode operations is proposed in this paper. Although sharing a common workspace, the robots are assumed to perform periodical tasks independently. The goal is to schedule the motion trajectories of the robots so as to avoid collisions among them. Rather than assigning the robots with different priorities and planning safe motion for only one robot at a time, as is done in most previous studies, an efficient method is developed that can simultaneously generate collision-free motions for the robots with or without priority assignment. Being regarded as a type of job-shop scheduling, the problem is reduced to that of finding a minimaximal path in a disjunctive graph and solved by an extension of the Balas algorithm. The superiority of this approach is demonstrated with various robot operation requirements, including “non-priority”, “with-priority”, and “multicycle” operation modes. Some techniques for speeding up the scheduling process are also presented. The planning results can be described by Gantt charts and executed by a simple “stop-and-go” control scheme. Simulation results on different robot operation modes are also presented to show the feasibility of the proposed approach.

The displacements of a vehicle on a plane can be subject to constraints depending on the nature of the vehicle. One can, for instance, think of the existence of a smallest turning circle for a car.

In this paper our purpose is to show, on a simple example, how such constraints can be handled. We, in fact, consider the case of a vehicle the motions of which consist of a finite sequence of rotations, each rotation being subject to the following constraints.

1) The radius of the circles along which the displacements of the vehicle take place are larger than a critical radius.

2) The centers of the successive rotations are located along a straight line defined by the geometry of the vehicle.

The mathematical analysis of this problem relies on a suitable choice of frames of reference in which the expression of the constraints is particularly simple. It is then shown that, under the above constraints, an arbitrary displacement can always be achieved by three approriate rotations.

An eight-legged walking machine with purely mechanical control of leg motion has been built, based on an old design by Space-General Corporation. The paper describes its mechanical design, and experiments with it on a variety of surfaces.

A rigid body dynamical model and control architecture are developed for the closed chain motion of two structurally dissimilar manipulators holding a rigid object in a three-dimensional workspace. The model is first developed in the joint space and then transformed to obtain reduced order equations of motion and a separate set of equations describing the behavior of the generalized contact forces. The problem of solving the joint space and reduced order models for the unknown variables is discussed. A new control architecture consisting of the sum of the outputs of a primary and secondary controller is suggested which, according to the model, decouples the force and position-controlled degrees of freedom during motion of the system. The proposed composite controller enables the designer to develop independent, non-interacting control laws for the force and position control of the complex closed chain system.

The use of Multi-Agent Systems as a Distributed AI paradigm for Robotics is the principal aim of our present work. In this paper we consider the needed concepts and a suitable architecture for a set of Agents in order to make it possible for them to cooperate in solving non-trivial tasks.

Agents are sets of different software modules, each one implementing a function required for cooperation. A Monitor, an Acquaintance and Self-knowledge Modules, an Agenda and an Input queue, on the top of each Intelligent System, are fundamental modules that guarantee the process of cooperation, while the overall aim is devoted to the community of cooperative Agents. These Agents, which our testbed concerns, include Vision, Planner, World Model and the Robot itself.

The 5-bar-linkage manipulator configuration is well suited to many industrial robotic applications. Aside from kinematic suitability, the dynamic equations are greatly simplified due to a decoupling of the manipulator inertia matrix. The design also lends itself to the use of direct drive motors. However, these motors must be capable of providing a high continuous torque to counter gravitational loading in the conventional manipulator design. In this paper, the static and dynamic design of the 5-bar-linkage manipulator is analysed. A technique is proposed whereby the motor torque requirements may be reduced to a fraction of those required in the conventional design, while simultaneously retaining the advantage of a decoupled inertia matrix. Details of a prototype manipulator and experimental results of its performance are presented.