Showing papers on "Revolute joint published in 1985"

Improving the absolute positioning accuracy of robot manipulators

Abstract: The absolute positioning accuracy of robot manipulator can be increased substantially by updating the nominal link parameters in the control software. This paper presents a general method to estimate the link parameter errors for any serial link manipulator (i.e., n links, and any combination of revolute and prismatic joints). The parameters are estimated through a linear kinematic model which relates the link bias errors to the end-effector positioning error. Only end-effector measurements are required instead of individual link measurements to implement this method.

Kinematics and Trajectory Synthesis of Manipulation Robots

Abstract: 1 Kinematic Equations.- 1.1. Introduction.- 1.2. Definitions.- 1.3. Manipulator hand position.- 1.3.1. Rodrigues formula approach.- 1.3.2. Homogeneous transformations.- 1.3.3. Spherical coordinates.- 1.3.4. Cylindrical coordinates.- 1.4. Manipulator hand orientation.- 1.4.1. Euler angles.- 1.4.2. Euler parameters.- 1.5. Manipulator hand velocities.- 1.5.1. Recursive and nonrecursive relations for linear and angular velocities.- 1.5.2. The Jacobian matrices.- 1.6. Summary.- 2 Computer-aided Generation of Kinematic Equations in Symbolic Form.- 2.1. Introduction.- 2.2. Symbolic kinematic equations.- 2.2.1. Backward and forward recursive relations.- 2.2.2. Kinematic equations for the UMS-3B manipulator.- 2.2.3. Backward recursive symbolic relations.- 2.2.4. Forward recursive symbolic relations.- 2.2.5. Treatment of revolute joints with parallel joints axes.- 2.3. The Jacobian matrix with respect to the hand coordinate frame.- 2.3.1. The Jacobian for the UMS-3B manipulator.- 2.3.2. Recursive symbolic relations for the Jacobian with respect to the hand coordinate frame.- 2.3.3. The Jacobian columns corresponding to parallel joints.- 2.4. The Jacobian matrix with respect to the base coordinate frame.- 2.4.1. The Jacobian for the UMS-3B manipulator.- 2.4.2. Recursive symbolic relations for the Jacobian with respect to the base coordinate frame.- 2.4.3. The Jacobian columns corresponding to parallel joints.- 2.5. Program implementation, numerical aspects and examples.- 2.5.1. Block-diagram of the program for the symbolic model generation.- 2.5.2. Examples.- 2.5.3. Numerical aspects.- 2.6. Summary.- Appendix I Direct Kinematic Problem for the Arthropoid Manipulator.- Appendix II The Jacobian with Respect to the Hand Coordinate Frame for the Arthropoid Manipulator.- Appendix III The Jacobion with Respect to the Base Coordinate Frame for the Arthropoid Manipulator.- 3 Inverse Kinematic Problem.- 3.1. Introduction.- 3.2. Analytical solutions.- 3.3. Numerical solutions.- 3.4. Summary.- 4 Kinematic Approach to Motion Generation.- 4.1. Introduction.- 4.2. Manipulation task.- 4.3. Trajectory planning.- 4.4. Motion between positions.- 4.4.1. Joint-interpolated motion.- 4.4.2. External coordinates motion.- 4.5. Procedurally defined motion.- 4.6. Summary.- 5 Dynamic Approach to Motion Generation.- 5.1. Introduction.- 5.2. Manipulation system dynamic model.- 5.3. An overview of methods for dynamic motion synthesis.- 5.4. Determination of the energy optimal velocity distribution using dynamic programming.- 5.5. Quasioptimal nominal trajectory synthesis using decentralized system model.- 5.6. Summary.- 6 Motion Generation for Redundant Manipulators.- 6.1. Introduction.- 6.2. Kinematic methods for redundant manipulator motion generation.- 6.3. Energy optimal motion synthesis.- 6.4. Obstacle avoidance using redundant manipulators.- 6.5. An algorithm for redundant manipulator motion synthesis in the presence of obstacles.- 6.6. Summary.- References.

Industrial robots with seven joints

Abstract: In a physical 3-dimensional free space at most six degrees of freedom can be independent, i.e. three for position and three for orientation. Intuitively robots with six joints are adequate to execute any tasks. However, in reality, constraints often exist under the complex environment so that six joints are not quite enough for the robots. An insertion of an additional joint into the robot may solve the problems. This paper discusses only the singularity problem at which the robot degenerates. The analysis, which is a continued investigation of a previous study, shows how the degeneracy entrapment could be escaped as rapidly as possible if the robot has seven joints; between which two joints the redundant joint should be inserted; and which type of joint (i.e revolute or prismatic) should be employed.

On the Optimal Selection and Placement of Manipulators

Abstract: This paper deals with the determination of manipulator proportions which minimize the time for motions starting from and ending in a rest state. These results also aid the layout of a manipulator workstation. The effects of physical constraints such as joint torques, overall length and joint travel limits are considered.

Generation and Evaluation of a Manipulator Workspace Based on Optimum Path Search

Abstract: This paper presents an algorithm using an optimization technique to outline the boundary profile of a manipulator workspace and perform quantitative evaluation of the workspace volume. The algorithm is applicable to general N -link manipulators with not only the revolute joints, but also joints of other types, such as, the prismatic and cylindrical joints. It is a partial-scanning technique which offers significant reduction on the number of scanning points to generate the workspace and the method is particularly efficient in dealing with complicated manipulator geometry. The [3 × 3] dual-number matrix method is used as the basis for analytical formulations, and consequently, computational advantage is gained. A comparative study is given with a previously used algorithm. Several specific examples involving industrial robots of various kinds are given to demonstrate the capability of the algorithm.

An efficient procedure for generating dynamic manipulator models

Abstract: An iterative procedure for obtaining dynamic model of manipulator has been proposed in this paper. The high efficiency of the procedure is reached on the basis of iterative relations of dynamic parameters. For general six revolute joint manipulator, the complete dynamic model i.e. matrices H(q), C(q), G(q) and vector of joint torques 13. requires 992 multiplications and 776 additions. When the complete dynamic model is given by 13. the number of operations reduces to 863 multiplications and 773 additions.

On the Dynamic Gear Tooth Loading of Planetary Gearing as Affected by Bearing Clearances in High-Speed Machinery

Abstract: The paper studies the effect of bearing clearances in the dynamic analysis of planetary gear mechanisms in high-speed machinery. For this purpose, an analytical model is developed based on the interdependence between kinematics and kinetic relationships that must be satisfied when contact is maintained between the journal and its bearing. The contact mode is formulated such that the bearing eccentricity vector must align itself with bearing normal force at the point of contact. The analysis mainly relies on determining the direction of the bearing eccentricity vector defined as the clearance angles βi at the bearing revolutes for each contact mode of the gear teeth. The governing equations of the clearance angles are developed using the geometrical constraints of the contact point location and the velocity ratio. The clearance angles and their derivatives are used to systematically evaluate kinematic and dynamic quantities. A rigid planetary spur gears with two revolute clearances is analyzed to illustrate the procedure.

Synthesis of Leg-Mechanisms of Biped Walking Machines : Part II, Synthesis of Foot-Driving Mechanism

Abstract: The paper describes a kinematic synthesis of a planner link mechanism with only revolute pairs to drive the foot which is attached to the ankle-path-generator obtained in the 1st paper. The ankle-joint angle and foot dimension necessary to realize a required gait have been determined in the case where the ankle-path-generator is predetermined. Then, a mechanism which is composed of a six-bar mechanism fixed on the thigh and a four-bar mechanism on the shank has been proposed and synthesized to drive the foot. A walking machine has been manufactured by combining the synthesized ankle-path-generator and the foot-driving mechanism with a mechanism for compensation of moments due to the gravitational and inertial forces. The machine has been experimentally confirmed to walk satisfying the given conditions.

Passive and Active Resistive Force Characteristics in Major Human Joints

Abstract: Effectiveness of the multi-segmented total-human-body models to predict realistically live human response depends heavily on the proper biomechanical description and simulation of the major articulating joints of the body. Short time transient response of the multi-segmented models requires proper characterization of the passive resistive force and moment data in articulating joints. Simulation of biodynamic events lasting more than a fraction of a second will also require the incorporation of active muscles into the multi-segmented models and constitute long-time response of the model.

Efficient Kinematic Transformations for the PUMA 560 Robot

Abstract: Efficient solutions for the kinematic positions, velocities, and accelerations for the six-degree-of-freedom PUMA 560 robot are presented. The kinematic problem is defined as the transformation from the Cartesian space to the joint space and vice versa. The solution method is based on a method that fully exploits the special geometry of the robot in the derivation of the solution. Special attention is given to the arm configuration in both directions of the transformation. HE TRANSFORMATION between the joint space and the Cartesian space of the robot is very important since robots are servoed in the joint space, whereas tasks are defined and object manipulated in the Cartesian space. The kinematic problem deals with the analytical study of the relation between these two spaces. The kinematic problem consists of two subproblems: the direct kinematic defined as the transforma- tion from the joint space to the Cartesian space and the inverse kinematic defined as the transformation from the Cartesian space to the joint space. If the desired motion of the end effector is not known in advance, these calculations have to be performed in real time so as to obtain a smooth motion of the arm. TO simpli& the kinematic solution, manipulators are usually designed so that the neighboring axes are orthogonal or parallel to each other and the three last joints form a spherical wrist. The spherical wrist allows the decomposition of the six- degree-of-freedom kinematic problem into two three-degree- of-freedom kinematic subproblems. Reasonably efficient algorithms have been developed for these transformations ( I)-(5). Featherstone's algorithms ( 11, which were derived for a coplanar, six revolute joints robot with a spherical wrist seems to be the most efficient for solving for the inverse kinematic positions and velocities. Hollerbach (6) extended this technique to calculate the inverse kinematic accelerations for the same robot. This paper presents efficient closed-form solutions for the kinematic positions, velocities, and accelerations for the six- degree-of-freedom, computer-controlled PUMA 560 robot based on Featherstone method (I). The PUMA robot is different from a coplanar robot by having offsets at the shoulder and elbow joints and also an asymmetry in the

A Design Method for Reducing the Effects of Clearances at Revolute Joints

Abstract: A method for designing a mechanism which is free of contact loss in clearance connections is developed. Only revolute joints are considered as possible clearance joints. Earles and Wu's empirical f...

Improvement of adaptive controller designs for robot manipulator systems yielding reduced Cartesian error

Abstract: A set of nonlinear coupled differential equations that represents mathematical model of a robot manipulator whose coefficients are unknown due to the effects of payload, friction and/or backlash, etc., is considered in this paper. It is shown that by proper compensation of the input torque the norm of the state error becomes less than that which is resulted from the conventional design. A Jacobian relation is introduced and being used in the design methodologies of the Lyapunov direct method and the hyperstability method to reduce the Cartesian error. These results are applied to a three-joint revolute manipulator to demonstrate performance improvement.

Contact Loss at Revolute Kinematic Joints: A ‘Ludodynamic’ Theory Tested

Abstract: An experimental apparatus has been used to investigate the conditions for loss of contact between the members of a ‘ludodynamic’ journal bearing, that is one with clearance but without hydrodynamic lubrication. In certain circumstances the results are approximately consistent with specific predictions that distinguish a theory published by the author from other theories. Other results are not correctly predicted by any of the theories cited.

Análisis cinemático y dinámico de sistemas mecánicos formados por varios sólidos rígidos

Abstract: SUMMARY In this paper a new method for the nunierical kinematic and dynamic analysis of multi-rigid-body systems is described. The method presented uses a neur system of non independent coordinates formed by the cartesian coordinates of some points of the mechanism and by the cartesian components of unitary vectors fixed to it, which determine the position and the motion of the multi-rigidbody system. The constraint equations arise from the rigicl body condition of each, element and from the pair constraint equations. The inclusion of unitary vectors as mechanism coordinates allows an easy formulation of pair constraints when the pair is related to a particular direction, as in revolute (R) cylindrical (C) or prismatic (P) pairs. The constraint equations are always linear or quadratic. The differential equations of motion are obtained easily through the application of the Theorem of Virtual Power. Some exarnples of dynamic analysis of planar and threedirnensional mechanisms are presented.