Showing papers on "Articulated robot published in 1991"

Robot Control: The Task Function Approach

Abstract: From the Publisher: A complete approach to the problem of controlling robot manipulators needs to bring together three scientific branches: computer science, mechanics, and automatic control.

System for controlling locomotion of legged walking robot

Abstract: A servo system for controlling locomotion of a biped walking robot to follow up a target angle for each drive predetermined in series with respect to time. The control is stabilized by reducing the load on the on-board computer through the provision of an analog circuit for velocity control which has to be carried out in short control cycle and a digital circuit for positional control which can be carried out in relatively long control cycle. For reducing the control deviation to substantially zero, open-loop control is adopted for the motor angular velocity so as to prevent delay from arising in the joint angle control and position feedback control is conducted only in case where a deviation arises between the target joint angle and the actual joint angle owing to external disturbance or the like.

Performance in adaptive manipulator control

Abstract: Effective adaptive controller designs potentially combine high speed and high precision in robot manipulation and further more can considerably simplify high-level programming by providing consistent performance in the face of large varia tions in loads or tasks. A simple, globally tracking-conver gent, direct adaptive manipulator controller has previously been developed and experimentally demonstrated. In this article, we further explore the performance issues linked to a computationally effective implementation. Specifically, we develop a recursive implementation applicable to both open and closed kinematic chains, as well as rules for obtaining minimal parametrizations. We also discuss implementations of the algorithm directly in Cartesian space, the exploitation of kinematic redundancies, and applications to adaptive compliant motion control. These developments are illustrated experimentally on a four-degrees-of-freedom articulated robot arm and suggest a wide range of application well beyond adaptati...

Adaptive Control of Robot Manipulators with Flexible Joints

Abstract: This paper presents an adaptive control scheme for flexible joint robot manipulators. Asymptotic stability is insured regardless of the joint flexibility value i.e. the results are not restricted to weak joint elasticity. Joint position and velocity tracking errors are shown to converge to zero with all the signals in the system remaining bounded.

Design of practical snake vehicle: articulated body mobile robot KR-II

Abstract: The characteristics and the applications of the articulated body mobile robot, 'Koryu (KR)', a mobile robot with a new style of articulated body is identified, and the construction of the newly developed 'Koryu-II (KR-II)' is discussed. KR-II takes the form of seven linked articulations and its total length is 3.3 m, and its total weight is 350 kg. KR-II introduces new mechanisms and control systems such as: easily detachable unified segments; self-contained driving system with wireless control; traction wheels attached on one side of the segment; long stroke vertical prismatic joint to cope with a steep inclination; robot hand driven by the coordination control of the body articulation; force sensor based on photodetective technology; and an analog bus system to simplify the electrical installation. Finally, the paper describes KR-II's fundamental results of experimental trials, to show the validity of it as a robot to move and operate in an unstructured environment. >

Experimental Evaluation of Friction Characteristics with an Articulated Robotic Hand

Abstract: In this paper some applications of dexterous robotic hands to fine manipulation operations are discussed. Common to this kind of operations is the important role played by the frictional characteristics of the fingers and of manipulated objects. The paper discusses a procedure for measuring apparent coefficients of friction between the fingertips and manipulated objects. To take into account real contact phoenomena, the distinction is introduced between translational and rotational friction limits. Reported experiments rely on force-based (intrinsic) contact sensing devices, implemented in the phalanges of an articulated robot hand (Salisbury Hand). Data collected during these procedures can be subsequently used for tasks such as recognizing the superficial features of objects, controlling the internal grasp forces exerted by the hand on delicate objects, and following the contours of the surface of unknown objects.

Three basic types of locomotion in mobile robots

Abstract: The types of locomotion in mobile robots, the fundamental problem in the design of mobile robot, are discussed and it is pointed out that there are three fundamental configurations in the mobile robot: wheels and crawler track; legs; and an articulated body The characteristics of these configurations are discussed Some of the examples of mobile robot are given >

Dynamic workspace analysis of multiple cooperating robot arms

Abstract: The authors focus on the investigation of maximum applicable force/torque by multiple robot arms in coordinated motion, i.e., the dynamic workspace analysis of multiple cooperating robot arms. Simple procedures to solve the dynamic workspace analysis problem for multiple cooperating robot arms with or without the internal force/torque constraint are presented. These procedures model the cooperating robot arms as a closed mechanical chain and are based on the theory of linear transformations and the properties of mechanics. For low degree-of-freedom robot arms, the maximum force/torque problem can be solved by geometrically using the proposed procedures, as illustrated by examples. >

Teaching robot's movement in virtual reality

Abstract: The authors propose a robot teaching method which uses virtual reality. An operator wearing a VPL DataGlove performs a task in a virtual workspace which simulates a real workspace. The operator's movements are recognized that interpreted task-dependently using interpretation rules and a world model. A robot executes the task in the real workspace using sensors. The overall system architecture and experiments are presented. >

New robot mechanisms for new robot capabilities

Abstract: The authors note a need to overcome the deficiencies inherent in conventional manipulator mechanisms. Joint torque controllability, optimal dynamic characteristics, motion redundancy, and fine manipulation ability are among the basic characteristics that would be desirable attributes of advanced robot systems. The paper discusses the limitations of current robot technology and describes the ongoing effort at Stanford University for the development of high-performance force-controlled robot systems to provide the advanced capabilities needed for carrying out dextrous manipulation tasks. >

Multiarm turning type articulated robot

Abstract: PURPOSE:To improve productivity by a method wherein a turning type articulated robot is formed in a multiarm type and is made endlessly turnable. CONSTITUTION:An intermittently indexed and rotated turning column 16 is provided with three articulated arms 22 actuated by an air actuator. A rotary joint 31 is located between a piping 32 on the fixed side on the air pressure source side to feed an air pressure to the air actuator of each articulated arm 22 and a piping 33 on the rotation side. A slip ring 41 is located in a wiring for feeding power to a solenoid valve 35 on the turning column side to control the direction of an air pressure, and the side of the power supply is electrically connected to the turning column side. A control command is inputted through an optical data transmission device 51 from the outside to a control part 44 on the turning column side to control the solenoid valve 35. The device 51 comprises a photo data communicating unit 52 located on a fixing plate 54 and a photo data communicating unit 53 formed integrally with the turning column 16, has the two units are positioned facing each other during the stop of the rotation of the turning column 16.

Force-Controlled Assembly of two Objects with a Two-arm Robot

Abstract: The use of a two-arm robot for assembling two objects, with each being held by one arm, is presented. The assembly task is decomposed into an approach phase and an assembly phase. For each phase, we propose a solution for describing the task. For the approach phase, we suggest to describe the task with respect to a mobile reference frame, attached to the end effector of one of the arms. This allows us to take advantage of the redundancy of the system. For the assembly phase, we propose two solutions, both involving some kind of force control. The first one is based upon a position control similar to the one used for the approach phase, with an updating of the reference position through a measurement of the contact forces. The second scheme is derived from a symmetrical hybrid control scheme initially proposed by Uchiyama and Dauchez to control a two-arm robot handling a single rigid object. The main results of this scheme are summarized, and the way of using it for an assembly task is presented. Finally, the experimental setup we have installed to validate our theoretical results is described.

Multiple robot coordination and programming

Abstract: The complexity of multiple robot coordination has added more functions to robot programming. The impact of the language statement is considered in connection with the support of multiple robot coordination. Requirements for a general-purpose robot control language are summarized, and several industrial applications of multiple robot coordination are discussed. Three types of group motion and their programming impact are reviewed: simultaneous motion, coordinated motion, and independent motion. Multitasking is also shown to be a necessary programming tool in multiple robot control. >

Forward and inverse kinematics of double universal joint robot wrists

Abstract: A robot wrist consisting of two universal joints can eliminate the wrist singularity problem found on many individual robots. Forward and inverse position and velocity kinematics are presented for such a wrist having three degrees of freedom. Denavit-Hartenberg parameters are derived to find the transforms required for the kinematic equations. The Omni-Wrist, a commercial double universal joint robot wrist, is studied in detail. There are four levels of kinematic parameters identified for this wrist; three forward and three inverse maps are presented for both position and velocity. These equations relate the hand coordinate frame to the wrist base frame. They are sufficient for control of the wrist standing alone. When the wrist is attached to a manipulator arm; the offset between the two universal joints complicates the solution of the overall kinematics problem. All wrist coordinate frame origins are not coincident, which prevents decoupling of position and orientation for manipulator inverse kinematics.

Industrial articulated robot provided with a driving linkage

Abstract: The present invention is intended to expand the operating region of a driven robot component of a robot by a provision of a driving linkage system for transmitting a drive torque of a drive source unit to the driven robot component, the driving linkage system having two spatially separated linkages, which are different from each other in the phase of motion thereof, to thereby transmit the drive torque from the drive source unit to the driven robot component by at least one of the two linkages even if the other linkage is brought to a dead center state, whereby the torque can be continuously transmitted to the driven robot component.

Construction robot system

Abstract: PURPOSE:To secure the safety in a construction site and to enhance the working efficiency, productivity, etc., to efficiently automate the construction work by communicating different functions mutually through communication network to disperse function or load. CONSTITUTION:A plurality of work robots 2-4 having different functions and a command robot 1 storing data such as assembly order, etc., of materials 5 are provided, and they are communicated mutually through communication network. After that, the command robot 1 is borne on a crane robot 3b, and they are assembled and fastened and are fixed to a steel frame structural body to hold. Then, the command robot 1 decides locations of materials 5 or robots 2-4 and progress of work through picture signals from a TV camera 6. The positioning robot 2 is held by the steel frame structural body 7, and the materials 5 are placed to positions in a design drawing. Successively, the connection robot 4 is loaded on the steel frame structural body 7, and the materials 5 are fastened to fix. In such a way, movement and positioning of the work robots 2-4 and holding and fastening of the materials 5 are performed through radio communications of the command robot 1.

Control method for articulated robot

Abstract: PURPOSE:To control flexible motion by dividing the axis of an articulated robot into less than six, setting first and second control points, and controlling the second control point setting the first control point as reference. CONSTITUTION:When the whole 12 axes are divided into every six axes and the linear interpolation of the motion of the control point P of a redundant axis that is the first control point and the control point Q of the finger of a robot that is the second control point to P1 P2 and Q1 Q2, respectively, are performed, respective interpolation calculation is performed with interpolation calculators 3, 4, and matrices S1 and T1 representing the position and the posture of an i-th number out of division numbers (n) are generated. The matrix T1 out of them is calculated setting the point P as reference. The control of the redundant axis is performed by performing the reverse conversion of the matrix S1 with a reverse converter 5. The control of a fundamental axis is performed by calculating a matrix U that is Ui=Si .Ti. and performing the reverse conversion of it with a reverse converter 6.

Method of controlling articulated robot

Abstract: A method of controlling an articulated robot having more than six axes and less than twelve axes, comprising: a first step in which the axes are divided into two groups each having six axes or less, and, with respect to the dividing point (P), redundant axes (11) are disposed on the side of a reference point and basic axes (12) are disposed on the side of fingers (Q); and a second step in which the dividing point (P) is regarded as a first control point and the fingers (Q) are regarded as a second control point, whereby the first control point is interpolation-controlled, and the first control point thus interpolation-controlled is regarded as a new reference point, whereby the second control point is further interpolation-controlled, so that all of the axes of the articulated robot are interpolation-controlled.

Multiprocessor control system for industrial robots

Abstract: This paper describes an advanced robot control system based on the three parallel processor boards. The controller has been designed as a general-purpose robot control system dedicated to controlling industrial robots with up to six degrees of freedom. The controller is based on a disk-oriented real-time operating system. The entire set of robot parameters can be monitored and changed by the user on-line. Source files, compilers, linkers and various utilities are provided as well. The main software layers include robot program interpreter, manipulator control facility, robot kinematics, dynamic feed-forward compensation, and digital servos. Basis, hand and joint coordinates are supported. Point-to-point and continuous path motions are provided. Digital and analog IO modules are included for synchronization with an environment. An acquisition system for monitoring and graphical presentation of robot coordinates, velocities and IO signals is provided. The paper ends with some experimental results for a six-degree of freedom robot.

Control of robot manipulators with joints flexibility

Abstract: In this paper we consider two stage controllers for motion control of robot manipulators with joint flexibilities. The dynamic equations of a manipulator with flexible joints are reparametrized in a model, with two blocs, suitable for control laws design. A passivity based adaptive compensator is proposed to control the reduced complexity model (the first bloc) with Integral (I) adaptation algorithms. The second stage uses a computed torque with a robust stabilization loop. The stability and robustness properties of this control scheme are analysed and the performances of the controllers are evaluated in simulation study and compared to other schemes. The proposed scheme allows the use of the controllers proposed for rigid manipulators.

Development of a mobile robot controlled by three motors for hostile environment

Abstract: In this study a hybrid legged/wheeled mobile robot, KAMOBOT, is developed. The mobile robot has a six-legged cylindrical configuration, each leg of which is equipped with a wheel at the bottom. The robot can go up and down stairs, go over obstacles, move along curvilinear paths and rotate around its geometric center. Such maneuverability can be achieved by using only three electric motors. In this study several gate modes are analyzed and algorithms for gate control are presented. >

A device for supporting a robot on a support beam

Abstract: An articulated robot has a pincer-like attachment with a central part and two pivoting parts articulated to the central part, the attachment serving to connect the robot to a support beam in a fixed or slidable manner.

Industrial robot device

Abstract: PURPOSE:To smoothly perform palletizing-depalletizing work by providing the second arm of a horizontally articulated robot arm in a manner possible to protrude from and retract to the side of the first arm by a servo control. CONSTITUTION:By driving a servo motor 23, the second arm 20 is slided by the engaging action of a pinion and a rack 25 along an LM guide 26, protruded from and retracted to a side of the first arm 19. Accordingly, by retracting the second arm 20 to the side of the first arm 19 by the necessary amount for palletizing-depalletizing work, the totalized length of the first and second arms is substantially reduced. In this way, the first arm 19, can be prevented from interfering with an adjacent load.

A joint space technique for real time robot path planning

Abstract: An elegant and fast path planning system is presented. The main part of the system comprises a robot 'Path Planner' and 'Path Improver' containing a geometric model of the static environment and the robot. The robot structure is modelled as connected cylinders and spheres and the range of robot motion is quantised. To test the techniques a system was constructed that used a dynamic geometric 'World Model' updated by a vision system. Obstacles were placed in the path of a robot and the results are presented. >

Industrial use robot with horizontal multiple articulated arms with means to minimize or eliminate interference among driving portions

Abstract: Robots for industrial use having an arm mechanism of a horizontal multiple articulated type. The load movement mechanism and the arm expansion mechanism, which are provided within the robot arms in advance with respect to the change condition through the catching of the gravity force changes by the force sensor from a case where the weight is moved, placed to a case where nothing is grasped, are properly operated, so that the mutual dynamic interferences of the respective driving portions of the robot may not be caused or may be made minimum, and may be made simple in shape by the comparatively simple control apparatus, with an effect that the superior robot which is capable of stable operations may be realized.

Study of an intelligent hexapod walking robot

Abstract: Concerns a hexapod walking robot designed for use in living and working spaces where it is necessary to ascend and descend structures such as stairs. It is designed to carry loads while always maintaining horizontal balance. It has eight CPUs for controlling the movement of twenty driving motors and for detecting attitude and its environment. It can move around autonomously as well as according to the operator's commands. The robot's configuration, structure and mechanism, and intelligence, are discussed. >

Robot Control in Singular Configurations - Analysis and Experimental Results

Abstract: This paper describes analytical and experimental work for controlling robotic manipulators in the neighbourhood of kinematically singular configurations. The proposed method is based on a damped least-squares solution with user-defined accuracy. Results are given for a five-joint industrial robot.