Showing papers on "Robot published in 1985"

Real-time obstacle avoidance for manipulators and mobile robots

Abstract: This paper presents a unique real-time obstacle avoidance approach for manipulators and mobile robots based on the "artificial potential field" concept. In this approach, collision avoidance, traditionally considered a high level planning problem, can be effectively distributed between different levels of control, allowing real-time robot operations in a complex environment. We have applied this obstacle avoidance scheme to robot arm using a new approach to the general problem of real-time manipulator control. We reformulated the manipulator control problem as direct control of manipulator motion in operational space-the space in which the task is originally described-rather than as control of the task's corresponding joint space motion obtained only after geometric and kinematic transformation. This method has been implemented in the COSMOS system for a PUMA 560 robot. Using visual sensing, real-time collision avoidance demonstrations on moving obstacles have been performed.

Robot Hands and the Mechanics of Manipulation

Abstract: Robot Hands and the Mechanics of Manipulation explores several aspects of the basic mechanics of grasping, pushing, and in general, manipulating objects. It makes a significant contribution to the understanding of the motion of objects in the presence of friction, and to the development of fine position and force controlled articulated hands capable of doing useful work. In the book's first section, kinematic and force analysis is applied to the problem of designing and controlling articulated hands for manipulation. The analysis of the interface between fingertip and grasped object then becomes the basis for the specification of acceptable hand kinematics. A practical result of this work has been the development of the Stanford/JPL robot hand - a tendon-actuated, 9 degree-of-freedom hand which is being used at various laboratories around the country to study the associated control and programming problems aimed at improving robot dexterity. Chapters in the second section study the characteristics of object motion in the presence of friction. Systematic exploration of the mechanics of pushing leads to a model of how an object moves under the combined influence of the manipulator and the forces of sliding friction. The results of these analyses are then used to demonstrate verification and automatic planning of some simple manipulator operations. Matthew T. Mason is Assistant Professor of Computer Science at Carnegie-Mellon University, and coeditor of Robot Motion (MIT Press 1983). J. Kenneth Salisbury, Jr. is a Research Scientist at MIT's Artificial Intelligence Laboratory, and president of Salisbury Robotics, Inc. Robot Hands and the Mechanics of Manipulation is 14th in theArtificial Intelligence Series, edited by Patrick Henry Winston and Michael Brady.

Historical perspective and state of the art in robot force control

Abstract: This presentation combines historical lineage, assessment of the state of the art, and representative videotapes on robot force control. The difference between continuous and logic branching strategies is described. The development of various impedance strategies and hybrid methods is traced and compared. The problem of stability is discussed and remedies are related to higher strategy issues.

Navigation for an intelligent mobile robot

Abstract: A navigation system is described for a mobile robot equipped with a rotating ultrasonic range sensor. This navigation system is based on a dynamically maintained model of the local environment, called the composite local model. The composite local model integrates information from the rotating range sensor, the robot's touch sensor, and a pre-learned global model as the robot moves through its environment. Techniques are described for constructing a line segment description of the most recent sensor scan (the sensor model), and for integrating such descriptions to build up a model of the immediate environment (the composite local model). The estimated position of the robot is corrected by the difference in position between observed sensor signals and the corresponding symbols in the composite local model. A learning technique is described in which the robot develops a global model and a network of places. The network of places is used in global path planning, while the segments are recalled from the global model to assist in local path execution. This system is useful for navigation in a finite, pre-learned domain such as a house, office, or factory.

A subdivision algorithm in configuration space for findpath with rotation

Abstract: A recursive cellular representation for configuration space is presented along with an algorithm for searching that space for collision-free paths. The details of the algorithm are presented for polygonal obstacles and a moving object with two translational and one rotational degrees of freedom.

Parameter identification of robot dynamics

Abstract: This paper presents algorithms for identifying parameters of multi-degrees-of-freedom robotic arm. First, we outline the fundamental properties of the Newton-Euler formulation of robot dynamics from the view point of parameter identification. We then show that the Newton-Euler model which is nonlinear in some of dynamic parameters can be transformed into the equivalent model which is linear in dynamic parameters. We develop both on-line and off-line parameter estimation procedures. To illustrate our approach, we identify the dynamic parameters of the cylindrical robot, and the three degree-of-freedom positioning system of the CMU Direct-Drive Arm II.

Dynamic Models for Control System Design of Integrated Robot and Drive Systems

Abstract: The design of high performance motion controls for industrial robots is based on accurate models for the robot arm and drive systems. This paper presents analytical models and experimental data to show that interactions between electromechanical drives coupled with compliant linkages to arm link drive points are of fundamental importance to robot control system design. Flexibility in harmonic drives produces resonances in the 5 Hz to 8 Hz range. Flexibility in the robot linkages and joints connecting essentially rigid arm members produces higher frequency modes at 14 Hz and 40 Hz. The nonlinear characteristics of the drive system are modeled, and compared to experimental data. The models presented have been validated over the frequency range 0 to 50 Hz. The paper concludes with a brief discussion of the influence of model characteristics on motion control design.

Robotic grasping and fine manipulation

Abstract: 1. Introduction.- 2. Previous Investigations of Fine Manipulation and Grasping.- 2.1 Fine Motion and Control.- 2.2 Robotic Wrists.- 2.3 Applications to Assembly and Surface Finishing Tasks.- 2.3.1 Assembly.- 2.3.2 Surface Finishing.- 2.4 Passive Hands and Grippers.- 2.5 Active Hands and Grasping.- 3. Robot Tasks in a Metal-Working Cell.- 3.1 Task Descriptions.- 3.1.1 Materials Handling.- 3.1.2 Assembly.- 3.1.3 Grasping.- 3.1.4 Surface Finishing and Shaping.- 3.1.4.1 Contour following.- 3.1.4.2 Contour modification.- 3.2 Discussion: Coupled Fine and Gross Motions.- 4. A Wrist for Fine-Motion Tasks.- 4.1 Wrist Description.- 4.2 Control Architecture.- 4.3 Experiments.- 4.3.1 Contour Following.- 4.3.1.1 State estimation.- 4.3.1.2 Control law.- 4.3.2 Grinding.- 4.4 Discussion of Results.- 5. Analysis for an Active Robot Hand.- 5.1 The Promise of Further Dexterity.- 5.2 Introduction to Grasp Analysis.- 5.2.1 Grasping Model and Assumptions.- 5.2.2 Stiffness, Strength and Stability of a Grasp.- 5.2.3 Procedure for Establishing Grip Properties.- 5.2.4 Two-Dimensional Examples.- 5.2.4.1 Choosing among five grips: an example.- 5.2.4.2 An unstable example.- 5.3 Extension to Three-Dimensional Problems.- 5.3.1 Forward Force and Displacement Relations.- 5.3.2 Summary of Forward Transformations.- 5.3.3 Finger Motions and Constraints.- 5.3.4 Constraints at a Contact.- 5.3.4.1 Case 1: exactly determined.- 5.3.4.2 Case 2: under determined.- 5.3.4.3 Case 3: over determined.- 5.3.5 Computing Changes in Grip Force.- 5.4 A Closer Look at Contact Conditions.- 5.4.1 Point Contact.- 5.4.2 Curved Finger Contact.- 5.4.2.1 Effects of rolling motion.- 5.4.3 Very Soft Finger.- 5.4.3.1 Effects of deforming fingertip.- 5.4.4 Soft, Curved Fingertips.- 5.5 Examples.- 5.5.1 Pointed Fingers.- 5.5.2 Procedure for Left Finger.- 5.5.2.1 Discussion.- 5.5.3 Curved Fingertips.- 5.5.3.1 Discussion.- 5.5.4 Very Soft Fingers.- 5.5.4.1 Discussion.- 5.6 Summary.- 6. Natural Examples of Grasping.- 6.1 The Human Hand.- 6.1.1 Conformability.- 6.1.2 Muscles.- 6.1.3 Hand/Wrist Interaction.- 6.1.4 Finger Coupling and Specialization.- 6.1.5 Grasps.- 6.1.6 Sensation and Control.- 6.2 Other Natural Examples.- 7. Designing Hands and Wrists for Manufacturing.- 7.1 Wrist Design.- 7.2 Hand Design.- 7.2.1 Grasping vs Manipulation.- 7.3 Control.- 8. Summary and Conclusions.- Appendix for Grasp Analysis.- A.1 Matrix Identities.- A.2 Matrix Method for Under Determined Finger Motions.- A.3 Differential Jacobians.- A.4 Rolling Contact.- A.5 Details for Examples in Section 5.5.- References.

First results in robot road-following

Abstract: The new Carnegie Mellon Autonomous I and Vehicle group has produced the first demonstrations of road following robots. In this paper we first describe the robots that are part of the CMU Autonomous Land Vehicle project. We next describe the vision system of the CMU ALV. We then present the control algorithms, including a simple and stable control scheme for visual servoing. Finally we discuss our plans for the future.

Dynamic manipulability of robot manipulators

Abstract: The concept of dynamic manipulability measure of robot arms is proposed as a quantitative measure of their manipulating ability in positioning and orienting the end-effectors, which takes the arm dynamics into consideration. This measure is defined on the basis of the relation between the joint driving force and the acceleration of the end-effector. Some properties of the measure are established. A two-joint link mechanism is analyzed and its best posture is obtained under certain condition from the viewpoint of this measure. A numerical example is also given to illustrate the utilization of this concept for the design of robot manipulators.

Computation of input generalized forces for robots with closed kinematic chain mechanisms

Abstract: In some comercially available industrial robots such as the Cincinnati T3, and the Bendix MA-510, the actuator of the third joint, which is one of the larger actuators, is mounted on the same platform as that of the second joint in order to reduce the load on the second joint. With this arrangement, the torque that moves the third moving link is transmitted through a four-bar or five-bar linkage mechanism, which is a closed-chain structure having a planar motion. Although a variety of computational schemes for the input joint torques/forces of industrial robots having open-chain mechanisms can be found in the literature, an efficient method of computation for robots with closed kinematic chain mechanisms is not available. A computationally efficient scheme is presented for industrial robots having three-dimensional closed-chain linkages. First the closed-chain is virtually cut open, and the kinematics of the virtual open-chain mechanism are analyzed. The holonomic constraints are applied to the virtually cut joint. As a result, the spatial closed-chain linkage can be considered as a tree-structured open-chain mechanism with kinematic constraints. Based on the known recursive Newton-Euler formulation, a computational scheme is developed for industrial robots having three-dimensional closed kinematic chain mechanisms. Two examples are given illustrating the approach.

Robots and manufacturing automation

Abstract: From the Publisher: Surveys the wide spectrum of automated systems available to improve manufacturing productivity including robots, numerical control machines, programmable controllers, computer controllers and microprocessor-based automated systems. Completely updated, it features industry case studies, revised and expanded problem sections and new material on product design, CAD, Karnaugh Maps and CIM.

Navigation system and method for a mobile robot

Abstract: An opto/acoustic navigation system allows a mobile robot to detect and mate with a floating plug-equipped charging unit upon detection of the need for recharging of the robot's storage battery. A plurality of infrared (IR) emitters and sensors located on the robot and adjacent to the charger in combination with the robot's acoustic sensors allow the robot to locate the charger, move to within a predetermined distance of the charger, maneuver to a position directly in front of the charger, and then back into engagement with the charger's floating plug.

Dynamic visual servo control of robots: An adaptive image-based approach

Abstract: Sensory systems, such as computer vision, can be used to measure relative robot end-effector positions to derive feedback signals for control of end-effector positioning. The role of vision as the feedback transducer affects closed-loop dynamics, and a visual feedback control strategy is required. Vision-based robot control research has focused on vision processing issues, while control system design has been limited to ad-hoc strategies. We formalize an analytical approach to dynamic robot visual servo control systems by first casting position-based and image-based strategies into classical feedback control structures. The image-based structure represents a new approach to visual servo control, which uses image features (e.g., image areas, and centroids) as feedback control signals, thus eliminating a complex interpretation step (i.e., interpretation of image features to derive world-space coordinates). Image-based control presents formidable engineering problems for controller design, including coupled and nonlinear dynamics, kinematics, and feedback gains, unknown parameters, and measurement noise and delays. A model reference adaptive controller (MRAC) is designed to satisfy these requirements.

Remotely controlled and/or powered mobile robot with cable management arrangement

Abstract: A mobile robot remotely controlled and/or powered through a cable from a stationary console is provided. The robot carries a cable management arrangement which stores the cable and dispenses and retracts it as needed. The arrangement lays down the cable under zero tension when the robot is outbound and reels it in as the robot returns to allow the robot to follow a tortuous path without entangling the cable under or around obstacles. The robot can have numerous configurations such as a simple configuration for use as a transporter for mail in an office and parts in a factory, to a complex configuration with robotic arms and sensors for use in remote surveillance and security work. The robot is especially usable in hostile environments such as nuclear power plants and has a containment box permitting it to be moved to numerous locations without contaminating other areas.

Robotics for Engineers

Abstract: Robotics for engineers , Robotics for engineers , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Robot controlling system

Abstract: A system that utilizes a robot for a loading operation of articles of works in a machine; a depalletizing operation for taking out the articles or the works one by one which are stacked up in a magazine at an assembly work station and a palletizing operation for stacking up the articles or the works one by one which are machined or assembled

Dynamic world modeling for an intelligent mobile robot using a rotating ultra-sonic ranging device

Abstract: A system which performs task-oriented navigation for an intelligent mobile robot is described in this paper. This navigation system is based on a dynamically maintained model of the local environment, called the "Composite Local Model." The Composite Local Model integrates information from a rotating sonar sensor, the robot's touch sensor and a pre-learned Global Model as the robot moves through its environment. Techniques are described for constructing a line segment description of the most recent sensor scan (the Sensor Model), and for integrating such descriptions to build up a model of the immediate environment (the Composite Local Model). Model integration is based on a process of reinforcing the confidence in consistent information while decaying the confidence in inconsistent information. The estimated position of the robot is corrected by the difference in position between observed sensor signals and the corresponding symbols in the Composite Local Model. This system is useful for navigation in a finite, pre-learned domain such as a house, office, or factory.

Real time tracking control for taught path robots

Abstract: A real time steering capability is provided to permit robot motion to be modified continuously in three dimensions as the robot is moving along a taught path. An arc welding robot or other taught path robot has a sensor located on the robot arm to sense the position of a desired path. The tracking control provides real time steering commands to the standard robot taught path and are calculated based on maintaining a constant, preprogrammed velocity along the desired path and coordination with the taught path. Offsets to the robot taught path are computed in a manner that allows the robot to smoothly follow the actual path as measured by the look ahead path sensor. The offsets are determined as separate x, y, z and twist integrations for the end effector and represent the total deviations from the robot taught path.

Robot performance measurements using automatic laser tracking techniques

Abstract: This paper describes two laser tracking techniques currently under development at the National Bureau of Standards for robot performance measurements. Tests indicate that the system can be used in real-time to determine the three-dimensional static and dynamic positioning accuracy of a robot end-effector to a few parts in 100,000 (i.e. 12.5–50 μm for a medium to large size robot), and wrist orientations to within 2 sec of arc. Both systems would be simple and compact enough to be considered as a general-purpose portable calibrating tool for robots (or CNC machines), or as an integral part of a robotic system providing real-time position feedback of the end-effector independent of the position and angle feedback of joint members. The ability to dynamically and statistically measure the position of an end-effector to the above accuracy has significant ramifications with regard to meaningful robot performance measurements, and the potential of these systems in other industrial and engineering applications.

Sensory feedback structures for robots with supervised learning

Abstract: A concept for sensory feedback and sensor-based teach-in in robotics is presented. Based on previous work of different authors a scheme of hybrid sensory-position control is proposed and has been realized that interpretes every "rudimentary" teach command in terms of sensory interaction with the environment by generating the socalled "artificial constraints" and the refined path automatically. Robots with arbitrarily programmable stiffness are one outcome of our technique. Motion commands and sensor data are stored together. The latter ones are then available as reference values for the repetition mode in a possibly changing environment. It is shown that by introducing pseudo-forces/torques the proposed techniques are equally applicable to different kinds of sensor, as are force-torque-sensors, range finders or inductive sensors. The "sensor-ball"-technique as developed at DFVLR is discussed as one physical realization. Operational systems of this kind, first tested with an ASEA robot in our lab, are going into industrial application now.

Control of two coordinated robots in motion

Abstract: When two coordinated robot touch a same object, the three form a closed kinematic chain mechanism. When the chain is in motion, the position and orientation of the two robots must satisfy a set of holonomic equality constraints for every time instant. In addition, when the joint velocities and accelerations of one robot is planned, that of the second robot are determined through two more sets of constraints. Based on the constraint conditions, the joint torques can be computed from the dynamic equations of the robots. The computed torques serves as control inputs to the two robots to generate their coordinated motions as planned.

Industrial Robots: Computer Interfacing and Control

Abstract: Industrial robots: computer interfacing and control , Industrial robots: computer interfacing and control , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Discrete dynamic robot models

Abstract: An inherently discrete-time dynamic model is introduced for robotic manipulators. Although robot dynamics are highly coupled and nonlinear, the model is compact and suitable for control engineering applications. The model is designed to guarantee conservation of energy (and momentum, if appropriate) at each sampling instant. Initial numerical experiments with cylindrical robots confirm the feasibility and applicability of the discrete dynamic robot model.

Minimum-time path planning for robot arms and their dynamics

Abstract: Despite its close relationship to robot arm dynamics, conventional path planning does not take it into account, leading to the possible underutilization of the robot's capabilities. The authors have developed a minimum-time path-planning method in joint space taking into consideration robot arm dynamics as well as other realistic constraints. The main differences between this method and others are: (1) an absolute tolerance in the path deviation at each corner point can be specified; (2) local upper bounds on joint accelerations are derived from the arm dynamics so as to nearly fully utilize robot's capabilities; and (3) a set of local optimization problems, one at every local corner point, replaces the global minimum-time problem, thus making the minimum-time path-planning problem simpler and easier to solve. The method is applied to the path planning of the first three joints of the Unimation PUMA 600 series robot arm, using its simulator on a DEC VAX-11/780. The results show significant improvements in the total traveling time in addition to the ease and simplicity obtained from the decomposition of the global problem into a set of local optimization problems.

The Development of a European Benchmark for the Comparison of Assembly Robot Programming Systems

Abstract: Many robot manufacturers claim that their machines are suitable for assembly operations, but before embarking on an automated assembly project, a user would be well advised to look beyond the mechanical performance of the rival machines and to look closely at the software features offered.

A Mobile Platform for Nursing Robots

Abstract: This paper describes a computer-controlled vehicle which is part of a nursing robot system currently under development at the Technion-Israel Institute for Technology. The platform of this vehicle can also be used for household robots. Design considerations, control algorithms, and the necessary sensory devices are discussed. The vehicle applies a motion control strategy which avoids slippage and minimizes position errors. Experimental results, performed on a prototype vehicle, are described as well.