摘要:

AbstractBased on the theory of variable structure systems (VSS), control system design for the trajectory control of robotic systems is presented. It is assumed that the parameters of the system are uncertain and unknown frictional torques are acting at the various joints of the arm. For simplicity, the control of a three‐link PUMA arm is considered. For trajectory following, two control laws, CHand Cθ, based on the choice of coordinates of the end effector or joint angles as the controlled outputs, respectively, are derived. It is seen that whereas control Cθhas no singularity, certain singular surfaces arise where feedback elements of CHbecome infinity. These singular surfaces describe the boundary of the reachable region (workspace). Digital simulation results are presented to show that accurate trajectory following can be accomplished using the control CHor Cθfor large maneuvers of the arm in spite of the uncertainty in the sy

ISSN:0741-2223    

DOI:10.1002/rob.4620060202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractRedundant manipulators provide increased flexibility for the execution of complex tasks. Redundancy is often required to maintain manipulability and avoid obstacles while completing the required task. Self‐motion is the internal (joint) motion of the manipulator that does not contribute to the end effector motion. In this article we provide a dynamic feedback control law that guarantees the tracking of a desired end effector trajectory and provides redundancy resolution by making the self‐motion of the manipulator flow along the projection of a given arbitrary vector field. By choosing this vector field to be the gradient of a cost function, for example, the manipulator can be made to seek an optimum configuration. The effectiveness of the control law is illustrated with simulation resu

ISSN:0741-2223    

DOI:10.1002/rob.4620060203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe complexity of modern robotic workcells, consisting of many cooperating elements (e.g., robots, sensing systems) makes programming applications enormously difficult. Even when the application can be easily decomposed into workcelll operations, the tight coupling among these operations due to constraints on precedence and resource sharing makes it difficult to identify and take advantage of possible concurrency. Since robotic workcells are typically configured to repetitively perform an application, we seek to minimize the ‘cycle’ time required, by optimizing the order in which operations take place. Eventually, a sequential program must be written for each workcell element, and they must then execute concurrently. Commercial robot languages and systems provide neither the necessary tools for programming such a distributed collection of elements nor a mechanism for inter‐element communication. In this article the authors propose a two‐part solution to this workcell programming problem: SAGE/WRAP. A graphics interface is provided to the user in order to define the application. Then, from the user's input, SAGE builds a Petri Net description of the workcell application; this is used to obtain a time‐optimal sequence of operations for each workcell element. The time‐optimal sequence then becomes the basis of the runtime program that performs the application. This program is interpreted and executed by the hierarchical workcell runtime environment called WRAP. An example is provided to illustrate t

ISSN:0741-2223    

DOI:10.1002/rob.4620060204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractA computationally efficient method for manipulator dynamic analysis is presented. This method adopts two schemes to improve the computational efficiency. First, it takes the advantage of the following geometric feature of most manipulators: For the first three‐degree‐of‐freedom (DOF) mechanism (positioning mechanism), all the links are moving in a principal plane that is rotating about the base axis with respect to the ground. With this geometry, only three equations of motion per link, two equations for the forces in the principal plane and one equation for the moments which are perpendicular to the principal plane, are needed for the inverse dynamic analysis of the first three‐DOF motion. Thus, the number of equations can be reduced to half. Second, this method adopts longitudinal and transverse force components at certain joints in the formulation of equations of motion. This eliminates the need of a simultaneous solution of many equations, which is necessary in conventional Newton‐Euler method. Hence, this method is more computationally efficient than the many existing dynamic analysis methods. Two examples, one is closed‐chain type and the other is open‐chain type, are used as

ISSN:0741-2223    

DOI:10.1002/rob.4620060205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe different means currently available for six‐axis wrist force sensor evaluation are discussed, and a unified criteria is proposed that is based on the condition number, the overall static and dynamic stiffness of the sensor, and the strain gauge sensitivity. In this light a new frame/truss type of sensor body design is introduced. The uniqueness of the design lies in the elastic members that exhibit truss (axial deformation), as opposed to the commonly used beam (bending) behavior. Several improvements over previous designs result, including: increased force sensitivity with a consistently low condition number, increased rigidity, and improved design flexibility. In addition, a design methodology is presented that uses optimization theory in combination with finite element analysis, to yield the best possible frame/truss force sensor design for a given set of specified principal force

ISSN:0741-2223    

DOI:10.1002/rob.4620060206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0741-2223    

DOI:10.1002/rob.4620060201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY