Showing papers on "Articulated robot published in 1990"

Design and control of a mobil robot with an articulated body

Abstract: Mobile robots having good terrain adaptability, sufficient payload capability, and high mobility are now urgently in de mand In this paper, design of a practical mobile robot is attempted, with an

Legged walking robot and system for controlling the same

Abstract: A biped walking robot and system for controlling the robot. The system provides smooth posture control by eliminating interference arising between the frictional force of the ground acting on the legs of the robot and the driving force of the leg joints. A six-dimensional force and torque sensor is provided to detect six force or moment components and based thereon, an angular command to joint motors is corrected. A joint structure of the robot is described, wherein the axes of the drive joints are arranged at right-angles to one another to thereby enable accurate positional control to be effected using Cartesian coordinates.

Six-degree-of-freedom articulated robot mechanism and assembling and working apparatus using same

Abstract: A six-degree-of-freedom articulated robot mechanism includes a three-degree-of-freedom translation unit for adjusting the position. The translation unit includes an orientation maintaining mechanism which has a rotation articulation of the direct drive type connecting a drive motor directly to an arm, and a link mechanism. A three-degree-of-freedom rotation unit for adjusting the orientation includes three rotation articulators of the direct drive type connecting a drive motor directly to a table, and the axes of the three rotation articulators intersect one another at one point.

Contact instability of the direct drive robot when constrained by a rigid environment

Abstract: A sufficient condition for the stability of robot manipulators in constrained maneuvers is derived. Attention is focused on the class of direct drive robots whose rigid links dominate the robot's dynamic behavior; compared to the robot, the environment is assumed to be infinitely rigid. The stability of the manipulator-environment system is investigated, and a bound for stable manipulation is determined. This bound is verified via simulation and experiment on the Minnesota direct drive robot. >

Collision-free trajectory control for multiple robots based on neural optimization network

Abstract: A collision-free trajectory control for multiple robots is proposed. The proposed method is based on the concept of neural optimization network. The positions or configurations of robots are taken as the variables of the neural circuit, and the energy of network is determined by combining various functions, in which one function is to make each robot approach to its goal and another helps each robot from colliding with other robots or obstacles. Also a differential equation of the circuit which tends to minimize the energy is derived. A new method for describing collision between articulated arms is presented and some heuristic method to improve the feasibility and the safety of the trajectory is proposed. Also illustrative simulation results for mobile robots and articulated robot arms are presented.

Collision-free motion planning for two articulated robot arms using minimum distance functions

Abstract: This paper presents a collision-free motion planning method of two articulated robot arms in a three dimensional common work space Each link of a robot arm is modeled by a cylinder ended by two hemispheres, and the remaining wrist and hand is modeled by a sphere To describe the danger of collision between two modeled objects, minimum distance functions, which are defined by the Euclidean norm, are used These minimum distance functions are used to describe the constraints that guarantee no collision between two robot arms The collision-free motion planning problem is formulated as a pointwise constrained nonlinear minimization problem, and solved by a conjugate gradient method with barrier functions To improve the minimization process, a simple grid technique is incorporated Finally, a simulation study is presented to show the significance of the proposed method

An extended operational-space control algorithm for satellite manipulators

Abstract: A new control algorithm, called the extended operational-space method, is presented for control of free-floating space robots. Experimental and simulation results are presented, for two-dimensional (laboratory) and three-dimensional (simulation) robot configurations. The method's significance is discussed for robot design, and for teleoperator and autonomous control of free-floating robots.

Shape recovery from robot contour-tracking with force feedback

Abstract: A process for shape recovery from robot contour-tracking operations with force feedback is described. Shape recovery is an important task for self-teaching robots and for exploratory operations in unknown environments. An algorithm which directs a position controlled robot around an unknown planar contour using the steady-state contact force information is described. A compensation process is explored for purposes of planar shape recovery. It is found through experimentation that the joint compliance is most conveniently compensated for in practice. Improvements in the shapes recovered from robot contouring are seen with the compensations. Experimental details and difficulties are also discussed. >

Payload capacity of balanced robotic manipulators

Abstract: The payload capacity of a conventional robot is usually limited as compared to the mass of the robot body. This is because a payload adds additional gravity loadings to the robot joints resulting in large input joint torques. To reduce the required input joint torques, the authors have proposed a mechanical balancing mechanism. Basically, the mechanism was designed to exactly balance the first three links of an articulated robot by adjusting the positions of counter-balancing masses so as to eliminate the gravity loading terms. Since the input joint torques are greatly reduced by adopting balancing mechanisms, a balanced robot is expected to carry heavier payload and move with higher speed and acceleration. This paper further investigates the possibilities of improving the payload capacity as well as speed and acceleration capabilities. These features were investigated under various operating conditions involving payload, maximum angular velocity, and acceleration period. Based upon the simulation results, the performances of the balanced robot are compared in detail with those of a unbalanced conventional robot.

Robot gripper having auxiliary degree of freedom

Abstract: A robot gripper module having a housing pivotally mountable to an end of a robot arm. The housing encloses a first motor for pivoting the housing about a pivot joint, and a second motor operating a rack-and-pinion gear arrangement for extending and retracting fingers. Two opposed groups attached to a rack on opposite sides of a pinion gear. Turning the pinion gear causes the fingers to move toward or away from one another. The motors which may operate independently of the robot arm, may be either servo or stepper motors. The gripper module provides additional degrees of freedom from that of the robot arm, enabling it to work with many kinds of robot arms.

System for exchanging tools and end effectors on a robot

Abstract: A system and method for exchanging tools and end effectors on a robot permits exchange during a programmed task The exchange mechanism is located off the robot, thus reducing the mass of the robot arm and permitting smaller robots to perform designated tasks A simple spring/collet mechanism mounted on the robot is used which permits the engagement and disengagement of the tool or end effector without the need for a rotational orientation of the tool to the end effector/collet interface As the tool changing system is not located on the robot arm no umbilical cords are located on robot

Initial experiments with a flexible robot

Abstract: A flexible three-degree-of-freedom robot is described, and its behavior is compared with a simple model of a vibrating system. The robot has three rotary joints and two flexible steel links, causing it to exhibit many complicated modes of vibration. A nondimensional analysis of the model showing how it responds to ramp commands and acceleration commands is presented, and the results are compared with those for the actual robot. Using the model, one can select input commands that minimize the vibration of the robot. >

Control primitives for robot systems

Abstract: A methodology is developed for describing of hierarchical control of robot systems in a manner which is faithful to the underlying mechanics, structured enough to be used as an interpreted language, and sufficiently flexible to encompass a wide variety of systems. A consistent set of primitive operations which form the core of a robot system description and control language is presented. This language, motivated by the hierarchical organization of neuromuscular systems, is capable of describing a large class of robot systems under a variety of single-level and distributed control schemes. >

Biologically Based Robot Control

Abstract: This paper presents the fundamental principles of a class of non-numerical, biologically- based robot control systems. The application of the principles is illustrated by describing the basic control of the Belgrade-USC multifingered robot hand.

Theory and Experiments on the Compliance Control of Redundant Robot Manipulators

Abstract: This work presents a control methodology for compliant motion in redundant robot manipulators. This control approach takes advantage of the redundancy in the robot’s degrees of freedom: while a maximum six degrees of freedom of the robot control the robot’s endpoint position, the remaining degrees of freedom impose an appropriate force on the environment. To verify the applicability of this control method, an active end-effector is mounted on an industrial robot to generate redundancy in the degrees of freedom. A set of experiments are described to demonstrate the use of this control method in constrained maneuvers. The stability of the robot and the environment is analyzed.

Robot controlling device

Abstract: PURPOSE: To approach a hand to a work with a competent angle, by providing a means which calculates the posture of a robot hand that the floating face of the robot hand becomes parallel to the longitudinal direction of a recognized work and the tip of the robot hand is inclined to the direction side recognizing the work by a visual device. CONSTITUTION: When a visual coordinate showing the existing position of a work is found by a visual device 20, this is converted into the coordinate system for a robot 60 and the motion target point of a robot hand 62 is calculated. Then the robot 60 makes the posture of approaching the robot hand 62 to this motion target point in the direction parallel to the longitudinal direction of the work that the floating face of the robot hand 62 is recognized and yet the robot hand 62 is inclined to the direction side recognizing the work 22 by the visual device 20, the posture of the robot hand 62 is decided based on this posture, and the offtake of the work 22 is performed with the robot hand 62 being moved to the motion target point. COPYRIGHT: (C)1992,JPO&Japio

Traveling robot and device therewith

Abstract: PURPOSE: To facilitate workability and maintenance inspection, by providing a control part which controls four axes including a traveling axis to the three axes of a horizontal articulated robot in order to rotate, revolve and reciprocate a work with its holding CONSTITUTION: A wrist rotating axis 1d which composes a horizontal articulated type robot rotates a work with its holding, a vertically moving axis 1c moves the wrist rotating axis 1d vertically, a front arm rotating axis 1f revolves on the circumference while vertically holding this vertically moving axis 1c at the tip of a front arm 1b, and a traveling axis 2 controls the wrist rotating axis 1d, vertically moving axis 1c and front arm rotating axis 1f of the horizontal articulated robot 1a and traveling axis 2 so that the traveling axis 2 may reciprocates the horizontal articulated robot 1a Consequently the work is rotated with its holding, moved vertically, revolved and reciprocated COPYRIGHT: (C)1992,JPO&Japio

Setting method for position of articulated robot

Abstract: PURPOSE:To facilitate the positioning in working even on any kind of a robot by providing a mark on one part of the arm of a robot and the installation face of the robot and a camera on the other part and forming the structure of operating the arm so that the mark picked up by the camera coincides with the reference position of the visual field inside of the camera. CONSTITUTION:In case of setting an arm at a reference attitude position, a camera 23 is first provided on an installation face 18 and a mark 21 is provided on an arm 16. In this case, the reference position inside the visual field of the camera 23 coincides with the position of the mark 21 of the time when the arm 16 is set at the reference attitude position. In this state, the arm 16 is whirled to position the mark 21 inside the visual filed of the camera 23. Then, the image signal transmitted from the camera 23 is processed by an image processing device 24 and the offset of the mark 21 to the reference position inside the visual field of the camera 23 is operated. Based on this arithmetic result, the position correction of the arm is performed and the mark 21 is made to coincide with the reference position of the visual field inside of the camera 23.

Interpolation of singular point passing for ptp teaching of articulated robot

Abstract: PURPOSE:To reduce errors with a target work coordinate track by realizing such an approximate solved track as connecting continuously and smoothly the solved tracks of the reverse kinematic equation that the before and after teaching points interposing a singular point differ respectively as the algorithm passing through the proper singular point of the link mechanism of an articulated robot. CONSTITUTION:The formation of a work coordinate track by an interpolation calculation is performed on the work coordinate system of an ordinary robot between the fore and aft teaching points in playback by teaching only the main point of the work by a teaching and playback method robot. A joint angle control is then performed by converting this formed work coordinate track into a joint angle coordinate track by a reverse kinematic equation finally. In this case, the approximate solved track like connecting continuously and smoothly the tracks of the reverse kinematic equation of the respectively different teaching points of before and after interposing the singular point (¦beta¦=90 deg.) is realized as the algorithm passing through the proper singular point (¦beta¦=90 deg.) of the link mechanism of an articulated robot.

Qualitative theory of robot grasping-A formalisation of 'intuitive' robot grasping

Abstract: A qualitative theory of robot grasping, as a formalized approach to intuitive robot grasping, is introduced. The qualitative theory is analogous to the analytical theory of robot grasping and consists essentially of symbolic abstractions of the analytically asserted theoretical concepts in robot grasping. A coexistence of the analytical and qualitative formulations of grasping theory is essential for developing 'intelligent' robot hands. >

Initial experiments in thrusterless locomotion control of a free-flying robot

Abstract: A two-arm free-flying robot has been constructed to study thrusterless locomotion in space. This is accomplished by pushing off or landing on a large structure in a coordinated two-arm maneuver. A new control method, called system momentum control, allows the robot to follow desired momentum trajectories and thus leap or crawl from one structure to another. The robot floats on an air-cushion, simulating in two dimensions the drag-free zero-g environment of space. The control paradigm has been verified experimentally by commanding the robot to push off a bar with both arms, rotate 180 degrees, and catch itself on another bar.