It is standard now in undergraduate and graduate courses in robotics to teach the basic concepts of position control design strategies. Due to the geared motors inherent in most educational and industrial manipulators, sophisticated control design strategies such as the inverse dynamics technique cannot be easily demonstrated in a laboratory setting. A direct drive 5-bar-linkage manipulator with reduced motor torque requirements is proposed in this paper for such a purpose. The manipulator dynamics are easily understood by undergraduates and an inverse dynamics control strategy is suggested which can be easily designed by students at the undergraduate level.

Continuing the work presented in part I, ‡ we consider the problem of moving a point robot through a two dimensional workspace containing polygonal obstacles moving on unknown trajectories. We propose to use sensor information to predict the trajectories of the obstacles, and interleave path planning and execution. We define a locally minimum velocity path as an optimal robot trajectory, given only local information about obstacle trajectories. We show that the complexity of a path planning problem can be characterized by how frequently the robot must change directions to approximate the locally minimum velocity path. Our results apply to both robots with and without maximum velocity limits.

A complication to the process of remotely generating tool paths is that mechanism controllers are typically capable of commanding a robot or machine tool to move along linear and circular arc space segments. This paper considers the decomposition of parametrically described, higher-order curvilinear paths into piecewise linear and circular path segments, thereby reducing the data required to store a higher order path.

This paper describes a novel form of navigation aid for mobile robots. It is suggested that a robot lay a heated trail to mark its path. This information about the robot trajectory can be used to assist a robot when it performs area coverage operations such as floor cleaning or allow a robot to follow the path previously taken by itself or another robot. Prototype devices for laying and tracking a heat trail are described and details of their performance are given. A mobile robot has been equipped to lay and track a heat trail.

An analysis is presented in this paper for the equilibrium of a class of parallel manipulators resembling the Stewart platform in a general form. General coordinates and 4 x 4 homogeneous transformations are employed to arrive at exact expressions for the force distribution in all six legs given the general 6-dimensional wrench (generalized force) at the upper platform of a parallel manipulator. Numerical examples are carried out to examine the validity of the approach and the accuracy of the numerical technique employed.

This paper discusses the problem of impact with robotic systems. The original method for the solution of impact is presented. The main idea is the replacement of impact with a singularity and hence the approach is called the IVSA (Impact-Via-Singularity-Analysis) Method. This goal is achieved by considering the obstacle as a unilateral constraint and introducing the new set of generalized coordinates so as to incorporate the constraint in the dynamic model. Using the IVSA Method the impact is not described by algebraic equations but by a reduced set of differential equations resulting directly from the initial dynamic model. The integration of dynamic equations over the impact points is thus possible. A numerical example is presented.

Many robotic tasks require the end-effector to come into contact with the external environment. In such complex tasks, the manipulator is constrained by the environment, and certain DOFs are lost for motion. The contact forces must be controlled in constraint directions, while the tip position is simultaneously controlled in the free directions.

The need to meet demanding control requirements in increasingly complex dynamical control systems under significant uncertainties makes neural networks very attractive, because of their ability to learn, to approximate functions, to classify patterns and because of their potential for massively parallel hardware implementation. This paper proposes the use of artificial neural networks (ANN) as a novel approach to the control of robot manipulators. These are part of the general class of non-linear dynamic systems where non-linear compensators are required in the controller.

Fluid power is one of the vast fields and its applications in manufacturing are not used for many real-time problems though its capabilities are known. One such application is fluid power for robotic systems. More specifically, in this study, a new hydraulic system is developed for use in actuating a robotic gripper. Electric motors were found unsatisfactory due to their poor power to weight ratio. Hydraulics were attempted using a master slave hydraulic system. Powering and positioning was done on the master cylinder, while the remote slave cylinder followed the motion. The control of the master cylinder was done with a ground based stepping motor and lead screw mechanism. Small hoses ran to the gripper based slave cylinder, which copied the motions.