Showing papers on "Articulated robot published in 1994"

Robot Evolution: The Development of Anthrobotics

Abstract: From the Publisher: Since the creation of the first modern robots in the 1950s, robotics has developed rapidly and in diverse directions; the term robot (from the Czech word for drudgery) now applies to a spectrum of creations, from mechanical limbs bolted to factory floors to computer-driven bipeds with human-like capabilities But the urge to create "mechanical men" to perform mundane, repetitive, and even complex human tasks is nearly as old as civilization itself The ancient Greeks built automata, as did the Egyptians and the Japanese Leonardo da Vinci designed mechanical men, and entertainment robots were all the rage in eighteenth-century Europe Robot Evolution is unique in robotics literature, at once a comprehensive pictorial history of robots and a technical guide to robot designs, devices, and systems Author and robot expert Mark E Rosheim reviews and describes the gamut of robot mechanisms, from ancient to state-of-the-art, from subcomponents such as joints, grippers, and actuators to completely integrated systems equipped with artificial intelligence, sensors, and autonomous mobility Rosheim chronicles the development and increasing complexity of these systems, using the kinesiology of human body parts as a framework for evaluating the kinematics of robotic components and explaining how these components are used to emulate human motion Particular emphasis is placed on the most advanced current devices and promising experimental designs Supplemented with hundreds of photographs, drawings, and illustrated tables, Robot Evolution is written in a clear, forthright style and organized to provide quick and easy access to information Separate chapters are devoted to robot arms, wrists, hands, and legs, and each chapter contains examples of several different design approaches to the same problem or component The advantages and disadvantages of each design are discussed in detail along with preferred applications and specific functions of each device An annotated bib

A spider-like robot that climbs vertically in ducts or pipes

Abstract: Different implementations of remote controlled robots with wheels or stepping mechanisms are in use that can inspect and repair the interior of a pipe or duct. However, autonomous locomotion in complex shaped hollows with corners, steps and branches remains a major challenge. This paper describes a robot with articulated legs that opens up the possibility of servicing complex pipe systems. To solve the pipe climbing task autonomously, the robot has a hierarchical control architecture with reflexive and reactive behaviour. Experiments were carried out in a 2D simulation as well as with an eight-legged robot test-bed. The experiments show the physical feasibility of such a robot, and that it is possible to achieve a robust, safe and powerful operation using reflexive and reactive behaviour. >

Wall-climbing robot for inspection in nuclear power plants

Abstract: A wall-climbing robot intended for inspection in nuclear power plants has been developed. The robot, small in size and modular, is made up of pneumatic components exclusively. Vacuum suction cups are used for sticking the robot to walls to be climbed. The robot motion, made up of both elementary translations and rotations, are accomplished by means of flexible pneumatic cylinders of rubber, which constitute the body of the mobile robot. A personal computer is used to command robot motion and a microprocessor controls the electronic valves of all pneumatic components. The paper presents the robotic system conceptual design and gives a detailed description of the mobile robot and its motion. >

Mousebuster: a robot for real-time catching

Abstract: A control methodology for catching a fast moving object with a robot manipulator, where visual information is employed to track the trajectory of the target, is described here. Sensing, planning, and control are performed in real time to cope with possible unpredictable trajectory changes of the moving target, and prediction techniques are adopted to compensate the time delays introduced by visual processing and by the robot controller. A simple but reliable model of the robot controller has been taken into account in the control architecture for improving the performance of the system. Experimental results have shown that the robot system is capable of tracking and catching an object moving on a plane at velocities of up to 700 mm/s and accelerations of up to 1500 mm/s/sup 2/. >

Robicen: A wall-climbing pneumatic robot for inspection in nuclear power plants

Abstract: A wall-climbing robot intended for inspection in nuclear power plants has been developed in the context of a cooperative research project which is being carried out by Iberdrola and Nuclenor (Electric Companies), on the one side, and CEIT (Research Centre), on the other. In the first phase of the project, the tasks to be accomplished with the robotic system are of an inspection nature in boiling-water reactor plants. The robot, small in size and modular, is made up of pneumatic components exclusively. Vacuum suction cups are used for sticking the robot to walls to be climbed. The robot motion, made up of both elementary translations and rotations, is accomplished by means of pneumatic cylinders, which constitute the body of the mobile robot. A personal computer is used to command robot motion and a microprocessor controls the electronic valves of all pneumatic components. The paper presents the robotic system conceptual design and gives a detailed description of the mobile robot and its motion.

Robot programming by human demonstration: the use of human variation in identifying obstacle free trajectories

Abstract: Programming by human demonstration is an intuitive method of robot programming, in which the programmer demonstrates how a task is performed using a human/robot teaching device that measures human motion, and the data gathered is used to generate the robot program. A direct duplication of the demonstrated trajectory would result in unnecessary robot motion due to human "wiggles" and unintended motion. To identify a more satisfactory robot trajectory, a method is presented that uses multiple demonstrations of the same task. Variation in human trajectories between trials is attributed to human inconsistency and is used to define an obstacle free region, by applying the Jordan curve theorem. The shortest path within the obstacle free region is determined, resulting in a shorter robot path than any of the demonstrations. Thus the presence of human inconsistency is used to improve robot performance. The analysis is restricted to planar translational motion. >

Experimental study on the dynamics and control of a space robot with experimental free-floating robot satellite (EFFORTS) simulators

Abstract: This paper presents an experimental study on the dynamics modeling and control of a free-floating space robot. In order to experimentally study the physical behavior of floating linkage dynamics and validate the practical availability of control schemes, the author developed the Experimental Free-FlOating RoboT Satellite (EFFORTS-I and -II) simulators, which enable us to examine two-dimensional pseudo-micro gravity motion dynamics using air lift systems. The robot models, comprising a satellite base body and articulated manipulator arm(s), make horizontal motions without mechanical disturbances or external forces. Theoretical concepts and corresponding experimental results are illustrated for the following topics that are relevant to the future of space robotics research and possible practical missions: (1) hardware design and development of the EFFORTS simulators, (2) dynamics modeling and basic control concepts for space free-floating manipulators, (3) target chasing and capturing control experiments, a...

Filtering Schilling manipulator commands to prevent flexible structure vibration

Abstract: The remediation and management of various nuclear sites will require inspection, removal and surveillance operations within many waste storage tanks. Due to the large dimensions, many tasks will be performed with a small articulated robot mounted on a long reach manipulator. However, the motion of the small arm tends to excite the vibrational modes of the larger structure. This paper presents several applications of a finite impulse response (FIR) compensation filter within the micromanipulator's joint feedback control structure to suppress the structure's flexible behavior. Simulation results of filtering a Schilling manipulator's azimuth joint commands while mounted on the tip of a long slender beam verify the effectiveness of the proposed control strategies.

A climbing robot with continuous motion

Abstract: A walking robot capable of moving with continuous motion on horizontal, vertical and over-hung curved surfaces has been developed. The robot is capable of moving a tool at a specified speed to follow complex paths on steel surfaces. The design, operation and control of the robot is discussed and some test results are presented. >

Adaptive robust fuzzy control for robot manipulators

Abstract: This paper presents an adaptive robust fuzzy control architecture for robot manipulators motion. The control objective is to adaptively compensate for the unknown nonlinearity of robot manipulators, which is represented as a fuzzy rule-base consisting of a collection of if-then rules. The algorithm embedded in the proposed architecture can automatically update fuzzy rules and, consequently, it is guaranteed to be globally stable and to drive the tracking errors to a neighborhood of zero. Focused on realization, hardware limitations such as traditional long computation line and excessive memory-space usage are also related by incorporating heuristic concepts, which reveals the flexible feature of this architecture. The present work is applied to the control of a five degree-of-freedom (DOF) articulated robot manipulator. Simulation results show that the proposed control architecture is featured in fast convergence. >

Sensor-based motion planning in three dimensions for a highly redundant snake robot

Abstract: A strategy is described for real-time motion planning for a highly redundant snake-like robot manipulator operating in a three-dimensional (3D) environment filled with unknown obstacles of arbitrary shape. The robot consists of many (say 30 or 50) links serially connected by universal joints (such a joint allows a 3D rotation of one link relative to the other). The robot's sensors allow it to sense objects in the vicinity of any points of its body. The task is to move the robot's tip point (its head) from its starting position to a specified target position, collision-free for the whole robot's body. To achieve the efficiency necessary for real-time computation, an iterative procedure is proposed which makes use of a unit motion for a single link based on the tractrix curve. This choice also results in automatically achieving a motion that is 'natural' (in that the joint displacements tend to 'die out' in the direction from head to tail) as well as locally optimal.

Robot operation training system

Abstract: To start robot training before an actual robot is manufactured or installed, the robot operation training system has a controller substantially the same as the actual robot controller and a personal computer for simulating the functions of the robot body. The training system can be applied easily to various robots of different models.

Automatic singularity avoidance using joint variations in robot task modification

Abstract: The research community has addressed the need to improve the flexibility of robot systems. Two particular concepts that have resulted from this research are off-line programming and modular tooling. These concepts are directed at allowing the robot system to be used to perform a variety of tasks with minimal setup time and to allow easy replication of an application. Both of these concepts require that the robot system have the ability to measure the position and orientation of features in the workspace. These measurements can then be used to perform coordinate transformations on each of the task data points. These modified task data points then, theoretically, facilitate the performance of the task by the robot system without human intervention. >

Motion Planning for an Articulated Robot: A Multi-Agent Approach

Abstract: Traditional motion planning techniques consider the problem of collision-free motion of an articulated robot as a global high level planning problem for one agent with internal degrees of freedom. The consequence is centralized explicit control of all joints. We suggest a simple multi-agent approach to motion planning with local low level collision avoidance. The control is distributed and there is no explicit control of the joints. Each individual link of a robot is a self-contained agent and the motion planning problem is formulated as a constraint satisfaction problem. Equations of motion for the multi-agent system incorporate satisfaction of the equality constraints between joined agents, while artificial forces ensure the satisfaction of inequality constraints preventing collisions. The artificial forces are local to each individual agent and solution of the equations of motion gives an emergent behaviour of the multi-agent system. The presented method has been successfully applied to various problems, including the simulation of a multi-tool robot and a 19-link snakelike robot moving through a maze. Finally, the method is used in an actual application: an industrial robot welding ship sections.

Autonomous robotic handling applying sensor systems and 3D simulation

Abstract: Industrial robots are not autonomous enough to cope with unexpected changes in their environment. The suitability of generated handling programs strongly depends on the locations of the objects to be handled. To deal with such problems, a system was developed at the IWB (Germany). The system consists of a mobile robot, a 3D simulation system, a sensor system and a computer which controls and coordinates all the components mentioned before. When an object is to be handled its actual position is determined by the sensor system and transferred to the simulation system. Reality and simulation are matched and the handling program of the robot is adapted to the actual situation. Finally, the handling program is transmitted to the robot control and the handling is done by the robot. >

Development of a 6-DOF High-Speed Parallel Robot HEXA

Abstract: The HEXA robot is a very fast 6-DOF parallel robot. It uses a parallel mechanism, called HEXA mechanism, which consists of a kinematic chain with five closed loops and is driven only by actuators at its base. This robot consists of six very simple elementary kinematic chains, each of which has only one active joint driven by a powerful DD motor. The moving parts of this robot is made very light at no expense of its stiffness. Therefore, this robot can move very fast and precisely. In this paper, we present development of a prototype of this robot. We choose a so-called Adept motion as a benchmark to measure its capability of fast motion. Experimental results show that the prototype robot can achieve the Adept motion in 0.465 [s/cycle] and prove that the HEXA robot is suited for very fast motion.

Method and apparatus for ultrasonic inspecting by articulated robot

Abstract: PURPOSE: To expedite the analysis by setting a rectangular coordinate system or polar coordinates fixed from a material to be inspected, and obtaining the distribution of an object to be inspected of the material to be inspected from the positional coordinates of a contact in the system always sent from a controller, echo information from an inspecting apparatus and refractive angle information of the ultrasonic wave. CONSTITUTION: A robot controller 3 controls a robot 1, converts the positional coordinates of an ultrasonic probe 2 from the coordinate system fixed to the robot 1 to a rectangular coordinate system or polar coordinates fixed to a welding material W, and always outputs the coordinate information. A detection controller 4 inputs the position of a welding defect at the material W from the coordinate information, echo information from an ultrasonic flaw detector 5 and refractive angle information of the wave, analyzes, stores and displays the distributed state of the defect of the material W. An arithmetic processor 6 is assigned the calculation and the analysis of the controller 4. COPYRIGHT: (C)1996,JPO

Hardware realization of inverse kinematics for robot manipulators

Abstract: For real-time processing of kinematic information required for intelligent robotic applications, a hardware realization of an inverse kinematics algorithm is a challenging task. This paper adopts an incremental unit computation method to accomplish the inverse kinematics of a three-axis articulated robot. This method starts from defining incremental units in joint and Cartesian spaces, which represent the position resolutions in each space. With this approach, calculation of the inverse Jacobian matrix can be realized through a simple combinational logic gate circuit. Furthermore, the incremental direct kinematics can be solved by using a digital differential analyzer (DDA) integrator. The hardware architecture to implement the algorithm is also described. Applying the hardware implemented by an erasable programmable logic device (EPLD) to the straight-line trajectory of an experimental robot, the authors have obtained an end-effector's maximum speed of 12.6 m/s. >

URK: Utah Robot Kit-a 3-link robot manipulator prototype

Abstract: In designing robot manipulators, the interaction between several modules (S/W, VLSI, CAD, CAM, robotics, and control) illustrates an interdisciplinary prototyping environment that includes different types of information that are radically different but combined in a coordinated way. This paper describes the analysis and design of a 3-link robot manipulator prototype as part of a research project for building a prototyping environment for electromechanical systems. This prototype robot can be used as an educational tool in robotics and control classes. >

Explicit fuzzy force control of industrial manipulators with position servo drives

Abstract: In this paper, a fuzzy force control algorithm is suggested for commercialized industrial robots equipped with the position servo drives, where control rules of the proposed fuzzy controller are changed according to the magnitude of environmental stiffness in such a way that good force response is maintained regardless of changes of environmental stiffness. Specifically, some fuzzy control rules are designed for several representative environmental stiffness values, and then a control action for a given arbitrary environmental stiffness value is decided by a fuzzy interpolation method. To show the validity of the proposed fuzzy controller, several experimental results are illustrated, where a 5-axis articulated robot manipulator equipped with the wrist force/torque sensor system and our prototype dual robot controller are employed. >

Automatic buffing method by robot

Abstract: PURPOSE:To provide an automatic buffing method wherein a position of a robot hand is automatically corrected for buffing, when a work is held by a robot to perform buffing, in buffing a front grille for an automobile. CONSTITUTION:This is a method using a perpendicular articulated robot to automatically perform buffing. An offset signal is issued to a robot, correction of a robot hand position is performed to strongly press a work, and perform buffing in order to keep polishing force constant when an electric current value is lower than a fixed value, in a buffing method wherein a work 4 is gripped by a robot 1, press-contacted with a buff 2a for polishing.

Biologically-inspired hexapod robot design and simulation

Abstract: The design and construction of a biologically-inspired hexapod robot is presented. A previously developed simulation is modified to include models of the DC drive motors, the motor driver circuits and their transmissions. The application of this simulation to the design and development of the robot is discussed. The mechanisms thought to be responsible for the leg coordination of the walking stick insect were previously applied to control the straight-line locomotion of a robot. We generalized these rules for a robot walking on a plane. This biologically-inspired control strategy is used to control the robot in simulation. Numerical results show that the general body motion and performance of the simulated robot is similar to that of the robot based on our preliminary experimental results.

Compliance control method for robot

Abstract: PURPOSE: To control optional machine compliance by compensating a gyro effect generated when a rotary body is arranged in a finger effector by reflecting it on a motion control method of a robot in a multidegree of freedom robot having a means to detect speed and external force. CONSTITUTION: In a multidegree of freedom articulated type robot 2, a sensor 1 is arranged in a wrist part so as to detect multidegree of freedom force and torque respectively. In this case, for example, a grinder 3 as a rotary body is arranged in a finger effector of the robot 2. On the other hand, a sensor is arranged on respective joints of the robot 2 so as to detect a turning angle or a turning angular velocity. The robot 2 is controlled by a control device 4, and optional machine compliance is given to the finger effector. That is, a gyro effect generated when the rotary body is arranged in the finger effector of the robot 2 is compensated by reflecting it on a motion control method of the robot 2. External force acting on the finger effector is estimated with high accuracy by removing the gyro effect. COPYRIGHT: (C)1994,JPO

Automatic welding device of steel frame joint part

Abstract: PURPOSE:To efficiently execute automatic welding work by precisely holding a steel frame joint part in accordance with various joint part shapes. CONSTITUTION:A device is constituted of an articulated welding robot 20, positioner 30 and control means 38, arranging the positioner 30 on a frame 28, having a disk body 32, which is free to rotate and be fixed at any angle and plural holding arms 34, which are capable of mutually attach/detach driving by hydraulic drive in the perpendicular two axes of the disk body, and is capable of holding one axis of a steel frame joint part 10 on cantilever. Also, it has a transfer means, which makes transfer and stop at any position of the articulated robot. The control means 38 overall controls the transfer means and the movement of the robot 20 and positioner 30. Further, the control means prepares each moving program by off line, executing welding work, at the same time, detecting a position deviation of the joint part 10 held with the positioner 30 by a sensor 42, automatically welding with correcting off line data.

Neural Network-Based Vision for Precise Control of a Walking Robot

Abstract: This article describes a connectionist vision system for the precise control of a robot designed to walk on the exterior of the space station. The network learns to use video camera input to determine the displacement of the robot's gripper relative to a hole in which the gripper must be inserted. Once trained, the network's output is used to control the robot, with a resulting factor of five fewer missed gripper insertions than occur when the robot walks without sensor feedback. The neural network visual feedback techniques described could also be applied in domains such as manufacturing, where precise robot positioning is required in an uncertain environment.

Coating apparatus for viscous material

Abstract: PURPOSE:To provide an apparatus capable of a quantitative coating by using a fixed quantity feeding device for viscous material. CONSTITUTION:The apparatus is equipped with a horizontal articulated robot 5, a viscous material feeding device 6, an acceleration/deceleration control part 3 for controlling the travel speed of the hands of the robot, and a abating time control part 2 for commanding the start/end of coating to the viscous material feeding device 6 and giving the travel speed command to the acceleration/deceleration control device 3. The acceleration/deceleration control part 3 operates the horizontal articulated robot 5 according to the set velocity V (s) and the action start command sent from the coating time control part 2. The viscous material feeding device 6 starts feeding the viscous material by the coating start command sent from the coating time control part 2 and stops feeding the viscous material by the coating finish command sent from the coating time control part 2, thus to constitute a coating apparatus for viscous material where the horizontal articulated robot is moved at a speed determined after considering the influence of non-fixed quantity prevailing at the time of coating start.

Development of an Articulated Multi-Vehicle Robot for Monitoring and Testing In Pipe

Abstract: This paper describes a composition of an articulated multi-vehicle robot in pipe, structure of each vehicle, and their control systems. Output pressure versus extension characteristic of the newly developed two-stage air cylinder, reduction of the wave reflection in a wheel-type ultrasonic probe, umbilical cable assembly housing optical fibers, air tubes and electric cables are treated. The articulated robot is designed and fabricated to demonstrate its travelling performance and automatic scanning of five probes for non-destructive test of a weld bead to the longitudinal direction. The results show that the robot can travel in the pipe of radius 520-800 [mm∅] from its entrance to the distance 150 [m] . The robot can pick up surrounding color images and transmit them to the ground station's monitor with sharpness. Also, the NDT is shown to be possible except in the vicinity of elbow area of the pipe.

Extensibility in local sensor based planning for hyper-redundant manipulators (robot snakes)

Abstract: Partial Shape Modification (PSM) is a local sensor feedback method used for hyper-redundant robot manipulators, in which the redundancy is very large or infinite such as that of a robot snake. This aspect of redundancy enables local obstacle avoidance and end-effector placement in real time. Due to the large number of joints or actuators in a hyper-redundant manipulator, small displacement errors of such easily accumulate to large errors in the position of the tip relative to the base. The accuracy could be improved by a local sensor based planning method in which sensors are distributed along the length of the hyper-redundant robot. This paper extends the local sensor based planning strategy beyond the limitations of the fixed length of such a manipulator when its joint limits are met. This is achieved with an algorithm where the length of the deforming part of the robot is variable. Thus , the robot's local avoidance of obstacles is improved through the enhancement of its extensibility.

Control of a single robot in a decentralized multi-robot system

Abstract: In a decentralized multi-robot system, each robot is controlled by an independent controller and the information obtained by each robot through its proprioceptive sensing devices is not shared with other robots. If the coordination of multiple robots in a cooperative manipulation task is to be accomplished, each robot must be able to exhibit controlled interaction with other robots and objects with minimal information. In this paper, the authors address the problem of maintaining rolling contact between a robot arm and an external, moving object. The authors assume that a nominal model of the motion of the moving object is available. The dynamic system that characterizes the motion of the robot arm and the moving object is acatastatic and nonholonomic. The authors design a nonlinear feedback for such a system that successfully maintains rolling contact. Simulation results are presented to demonstrate the effectiveness of the system. >

Motor control unit

Abstract: PURPOSE: To adjust a gain parameter according to the quantity of a robot fitting load. CONSTITUTION: A feedback control unit which controls the position and speed of an articulated robot including a front arm shaft that is unsteady in fitting load and operates a robot arm vertically is provided with a gain adjusting means 32 which operates the front arm shaft at a low speed by a front arm shaft low-speed driving command generating means 25 and detects the (q) shaft current of the motor driving the front arm shaft during the operation and the angular position of the front arm shaft at the start of the operation by a front arm shaft (q) current detecting means 28 and a front arm shaft angular position detecting means 26, calculates the value of a load fitted to the tip of the robot from the detected (q) shaft current 29 and angular position 27 by a tip fitted load calculating means 30, and adjusts the gain parameter of the feedback control loop of each joint shaft from the calculated value of the fitted load 31. COPYRIGHT: (C)1995,JPO