Showing papers on "Articulated robot published in 1984"

Coordinated control of two robot arms

Abstract: A computer control structure has been designed and implemented to enable two robot arms to function in a coordinated manner. One algorithm has been derived and implemented but not tested for a closed-loop configuration. Errors for the open-loop operation are given in the report.

Improving the precision of a robot

Abstract: Least square error methods are employed to improve the precision of a robot world coordinate system model. A solution which reduces the large scale errors of the robot is presented. This method is then applied to the task of vision directed workpiece reorientation.

Iterative coordinate transformation procedure for one class of robots

Abstract: A necessary feature of robot systems is a capability to process robot paths in terms of Cartesian coordinates. However, the so-called articulated robot arms which represent the more advanced systems operate in terms of their revolute and sliding joint coordinates, and these do not lend themselves easily to translation into Cartesian equivalents. As a rule, the direct (joint-to-Cartesian space) coordinate transformation can be solved for in closed form. As for the inverse (Cartesian-to-joint) transformation, for some rather common arm designs practical solutions cannot be found in closed form. An iterative procedure for one such class of articulated robots is presented. The procedure produces an exact solution for the wrist tip position coordinates and an approximate solution for the wrist orientation coordinates. The convergence characteristics of the procedure are discussed.

Cellular type robot apparatus

Abstract: This invention relates to a cellular type robot apparatus consisting of a plurality of cellular robots (11-34) each having intelligence wherein each cellular robot controls the operation of its own on the basis of information exchange with adjacent cellular robots, the operations of the cellular robots are as a whole coordinated, and each cellular robot can be controlled without the necessity of change of hard- and softwares even when a part of cellular robots is out of order or is expanded. Each cellular robot can be increased or decreased in a building block arrangement. More definitely, each cellular robot has arms corresponding to hands and feet, can control the operation by itself. As the cellular robots are connected and combined through transmission routes so as to exchange information, they can operate cooperatively as a group of cellular robots. The operation of the group of cellular robots is to constitute the shape of a predetermined pattern besides the operations of entwining an object, and gripping and moving the object.

Educational and laboratory work cell for a robotic device

Abstract: A robotic cell, or work area, especially useful for education. The cell has a plurality of interchangable work surfaces for mounting objects that the robot manipulates. Students, researchers, or other workers can thus set up separate experiments that need not be torn down each time a different user begins work with the cell. The cell has safety switches that encourage a user, when near the robot, to keep a hand on the robot so as not to be accidentally injured by the robot's motion. There is also a dead man switch effective to disenable the robot entirely, after a short time delay. The cell has a pneumatic control circuit that enables a user to position the robot's gripper arm at positions intermediate of fully up and fully down.

Arrangement on an industrial robot

Abstract: The invention relates to an arrangement on an industrial robot which is used for performing an operation on a workpiece (10). According to the invention, a sensor (S) is fastened to the robot hand (8). The sensor (S) senses the distance between the robot hand and the workpiece by means of optical triangulation. The robot is provided with control elements (RC) which control the robot hand during a first preprogrammed search movement in a direction which has a component parallel to the workpiece surface facing the robot hand. Furthermore, there are signal-processing elements (SC) which, with the aid of the distance detected by the sensor during the searching, determine the position of the workpiece in the search direction relative to the robot.

Singularity Low-Sensitive Motion Resolution of Articulated Robot Arms

Abstract: In this paper, singularity problem of articulated robot arms is discussed. The existence of singular points is an inherent problem in controlling articulated robot arms. The conventional motion resolution method using inverse matrices is not applicable at singular points. To make matters worse, in the neighbourhood of singular points, the closer a robot arm approaches singular points, the more the movement of joint angles is required for a given movement of the robot hand. It causes large errors in the motion of the robot hand because of the saturation of driving torques of joints. Singularity low-sensitive motion resolving matrix is defined, which improves the motion of robot arms in the neighbourhood of singular points. This motion resolution method is applicable to all types of articulated robot arms whether redundant type or non-redundant type. Keyword: articulated robot arm, singular point, motion resolution, redundant manipulator, manipulatability

Structures for Sensor-Based Robot Motion Control

Abstract: Feedback of end-effector position to robot controllers provides an effective means for compensating for manipulator path errors and variations in workpiece geometry. Most current robot controllers do not provide the facility for real-time path correction using sensor feedback; this capability will be an essential element of future robot control systems. This paper presents a comparison of two alternative control structures, as applied to realistic models of robot mechanical and microelectronic control systems.

Driving control method of articulated robot

Abstract: PURPOSE:To improve track control performance by providing a circuit which estimates a load torque component operating on each articulation driving system of the robot and compensating its output. CONSTITUTION:A position command value to each articulation driving system is supplied from a command generating part 1 to a D/A converter 101 and held by a sample holding circuit 102. The control system consists of a forward compensating element 28 for a position control system, a compensating element 29 for a speed control system, and a compensating element 30 for a current control system, and feedback is provided through the compensating elements 31-33. This is provided with the load torque estimating circuit 50 of the 2nd link driving system and the detected value of a current flowing through a motor 201 is multiplied by the torque constant of the motor 201 in the block 42 to calculate driving torque. Further, a block 27 performs integration to obtain an estimated value of the motor rotating speed and the value is compared with the actual detected value. Further, an estimated value of objective load torque is obtained and converted 43 into a current component, which is added to a current command value as a compensating component.

An Accuracy Test Procedure for Robotic Manipulators Utilizing a Vision based, 3-D Position Sensing System

Abstract: A vision based, three dimensional position sensing system was constructed and used to measure the positioning accuracy of an articulated robot arm. With a twenty-five millimeter lens, the sensor achieved a sensitivity of 0.004 inches for measurements along the focal axis of the camera and 0.001 inches for measurements perpendicular to the focal axis. The system was used to optically define a reference frame in the robot workspace and then to check the positioning accuracy of the manipulator as it was instructed to move within this reference frame.

Method for controlling robots or other machines and equipment for testing components

Abstract: In a method for controlling robots or other machines, a pattern is visually projected into the space in the working region of the robot. A detector on a movable arm of the robot scans the pattern if the movable part is situated in the working field. The output signal of the detector is used to control the robot so that it passes through a predetermined precise path or arrives at a location in the space. As a result, a precise outer reference coordinate system for the robot is provided, which is independent of mechanical movement quantities. The position of the robot arm is thus very precise at comparatively low cost for the mechanical means for moving the robot arm. The invention therefore relates to a simple visual guidance system which is universally usable in all types of automation systems and also in coordinate measuring machines.

Mobile robot with transformable crawler and intelligent guidance

Abstract: Recently, great advances have been made in intelligent mobile robot technology, advances which will provide autonomous travelling ability to robots, allowing them to surmount stairs and other obstacles. In this paper, we present an active adaptive crawler mechanism and a visual navigating system, developed to achieve practical speed for industrial use of the mobile robot. By using a crawler-type mechanism, the active adaptive suspension mechanism maintains vehicle stability and achieves good climbing capability without increasing weight. Further, we have developed technology for an intelligent navigating mechanism, to guide the robot as it passes through a building. Once the robot is provided with an inner layout plan of the respective building, it can achieve practical mobile speed for industrial use.

Structure, control and operation

Abstract: ONE Components of Robotic Systems.- General.- Mechanical Arm.- End Effector.- Robot Motors.- Computer (Controller).- Sensors.- Two The Mechanical Arm.- Mechanical Arm Structure.- Classifying Robots.- Cartesian Robots.- Cylindrical Robots.- Spherical Robots.- Horizontal Articulated Robots.- Vertical Articulated Robots.- Structural Characteristics of Robots.- Mechanical Rigidity.- Effects of Structure on Control.- Effects of Structure on Work Envelope and Work Volume.- Cartesian Robot Work Volume.- Cylindrical Robot Work Volume.- Spherical Robot Work Volume.- Horizontal Articulated Robot Work Volume.- Vertical Articulated Robot Work Volume.- Robot Work Volumes: Comparison.- Work Volume in Theory and Practice.- Advantages and Disadvantages of Various Kinematic Structures: Summary.- Open and Closed Kinematic Structures.- Wrist Joints.- Three Fundamental Concepts of Control.- Control Systems.- Open-Loop Control.- Closed-Loop Control.- Negative and Positive Feedback.- Control System Errors and Stability.- Transient and Steady State Response.- Stabilization and Servo Systems.- Loading Error.- Controller Types.- Proportional Control.- Integral Control.- Proportional-Integral Control.- Differential Control.- Proportional-Differential Control.- Proportional-Integral-Differential Control.- Four Electrical Drive Components.- DC Servo Motors.- DC Motor Structure.- The Motor as a Generator.- Opposite EMF in DC Motors.- Classifying DC Motors by Excitation Type.- Linear Regulation of Rate of Revolution in DC Servo Motors.- Pulse Width Modulation Control.- Stepping Motors.- Stepping Motor Controllers.- Stepping Motor Structure.- Stepping Motors: Summary.- Considerations in the Use of Stepping Versus DC Servo Motors.- Advantage of DC Motors.- Disadvantage of DC Servo Motors.- Advantage of Stepping Motors.- Disadvantage of Stepping Motors.- Five Hydraulic Drive Systems.- Properties of Hydraulic Fluids.- Analogies between Hydraulic and Electrical Parameters.- Principle of the Hydraulic Amplifier.- Reduction of Pressure Using a Venturi Tube.- Cylinders.- Cylinder Structure.- Piston Motion.- Piston Rate of Motion.- Selecting the Appropriate Cylinder.- Power Sources.- Gear Pump Structure and Principles of Operation.- Radial Hydraulic Motors.- Valves.- Directional Control Valves.- Regulating Valves.- Electrohydraulic Servo Valves.- Servo Valve Structure and Principles of Operation.- Six Feedback Devices.- Potentiometers.- Optical Encoders.- Resolution.- Range.- Absolute Position Encoder.- Incremental Position Encoder.- Computing the Resolution of Incremental Position Encoders.- Measuring Rates of Revolution Using Incremental Position Encoders.- Increasing the Resolution of Incremental Position Encoders.- DC Tachometers (Tachogenerators).- Seven Drive and Control Systems: An Appraisal.- Automatic Drilling Process: Computerized Control System for One Axis.- Operating Description.- Automatic Command for Filling Containers with a Constant Powder Volume.- Computer-Controlled System for Hydraulic Cylinder Position and Velocity Control.- System Description and Component Functions.- System Characteristics.- Description of Operation.- Hydraulic Cartesian Robot with Three Degrees of Freedom.- Eight Robot Path Control.- What is Path Control?.- Point-to-Point Control.- Point-to-Point Control: Summary.- Continuous Path Control.- Continuous Path Control Computations.- Joint Coordinate System.- World Coordinate System.- Tool Coordinate System.- Conversions within Systems.- Extracting Joint Variable Values for Robots with Two Degrees of Freedom.- Extracting Joint Variable Values for Robots with Three Degrees of Freedom.- Continuous Path Control in Practice.- Nine A Case Study.- Defining the Task.- Can this Robot Perform this Task?.- Do the Robot's Degrees of Freedom Enable it to Carry out the Task?.- Can the Robot Motors Move the Arm and the Payload?.- Is the Accuracy Achieved by the Robot Suitable to the Accuracy Requirements of the Task?.- Operation of the Robot Components during Execution of the Assigned Task.- Will the Motor Stop at that Point?.- What kind of Controller is Used in this Control System?.

Robotic software for the mini-mover 5 robot arm

Abstract: The aim of the project is to design and implement software on a MOTOROLA M68000 16 bit microprocessor to control a MINI-MOVER 5 robot arm PO Box 1144 WOLLONGONG NSW AUSTRALIA telephone (042)-270-859 telex AA29022 April 10 1984 ROBOTIC SOFTWARE FOR THE MINI-MOVER 5 ROBOT ARM