Showing papers on "Obstacle avoidance published in 1986"

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. Collision avoidance, tradi tionally considered a high level planning problem, can be effectively distributed between different levels of control, al lowing real-time robot operations in a complex environment. This method has been extended to moving obstacles by using a time-varying artificial patential field. We have applied this obstacle avoidance scheme to robot arm mechanisms and have used a new approach to the general problem of real-time manipulator control. We reformulated the manipulator con trol problem as direct control of manipulator motion in oper ational 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 kine matic transformation. Outside the obstacles' regions of influ ence, we caused the end effector to move in a straight line with an...

Avoiding obstacles and resolving kinematic redundancy

Abstract: While obstacles in a robot workspace can effectively reduce the number of degrees of freedom, there need not be a corresponding loss of functionality for kinematically redundant mechanisms. In this paper, disk-like obstacles for a planar three-bar mechanism are classified. The extended Jacobian technique is used to implement an obstacle avoidance technique based on optimizing a distance criterion. The feasibility of applying multiple constraints or optimality criteria for resolving redundancy is investigated.

Selection of near-minimum time geometric paths for robotic manipulators

Abstract: A number of trajectory planning algorithms exist for calculating the joint positions, velocities, and torques which will drive a robotic manipulator along a given geometric path in minimum time. However, the time depends upon the geometric path, so the traversal time of the path should be considered again for geometric planning. There are algorithms available for finding minimum distance paths, but even when obstacle avoidance is not an issue, minimum (Cartesian) distance is not necessarily equivalent to minimum time. In this paper, we have derived a lower bound on the time required to move a manipulator from one point to another, and determined the form of the path which minimizes this lower bound. As numerical examples, we have applied the path solution to the first three joints of the Bendix PACS arm and the Stanford arm. These examples do indeed demonstrate that the derived approximate solutions usually require less time than Cartesian straight-line (minimum-distance) paths and joint-interpolated paths.

The Potential Field Approach And Operational Space Formulation In Robot Control

Abstract: The paper presents a radically new approach to real-time dynamic control and active force control of manipulators In this approach the manipulator control problem is reformulated in terms of direct control of manipulator motion in operational space, the space in which the task is originally described, rather than controlling the task’s corresponding joint space motion obtained after geometric and kinematic transformation The control method is based on the construction of the manipulator end effector dynamic model in operational space Also, the paper presents a unique real-time obstacle avoidance method for manipulators and mobile robots based on the “artificial potential field” concept In this method, 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 Using a time-varying artificial potential field, this technique has been extended to moving obstacles A two-level control architecture has been designed to increase the system real-time performance These methods have been implemented in the COSMOS system for a PUMA 560 robot arm We have demonstrated compliance, contact, sliding, and insertion operations using wrist and finger sensing, as well as real-time collision avoidance with moving obstacles using visual sensing

A strategy for obstacle avoidance and its application to mullti-robot systems

Abstract: We present a local method for obstacle avoidance based on the existence of extreme separating hyperplanes. Its application is then extended to the coordinated motion of several mobile robots, and to the avoidance of two manipulators. The techniques of local planning we develop here prove to be an interesting substitute to the potential field method, as they provide a simple geometric support for the analysis.

Time optimal trajectory planning for robotic manipulators with obstacle avoidance: A CAD approach

Abstract: A method is presented which finds the minimum time motions for a manipulator between given end states. The method considers the full nonlinear manipulator dynamics, actuator saturation characteristics, and accounts for both the presence of obstacles in the work space and restrictions on the motions of the manipulator's joints. The method is computationally practical and has been implemented in a Computer Aided Design (CAD) software package, OPTARM II, which facilitates its use. Examples of its application to a six degree-of-freedom articulated manipulator, performing tasks in a typical environment, are presented. The results show that substantial improvements in system performance can be achieved with the technique.

Object level programming of industrial robots

Abstract: We present a system designed for object level programming of industrial robots. It contains essentially four modules : - a C.A.D. module to build geometric models of objects and manipulators and define the implantation of the robotic cell. - a pre-processing module which uses the cell model to compute a representation of the free-space in the joint space of the robot arm. - an obstacle avoidance module which uses this representation to perform different tasks such as testing or searching a safe trajectory. - a planning module that combines the elementary tasks of the obstacle avoidance module to get the environment from its current state to the state defined by an object level instruction. It can be used either during the conception step of a robotic cell or for programming fastly and safely an industrial robot.

An intelligent system for an autonomous vehicle

Abstract: This paper describes an intelligent full-size autonomous vehicle system which simultaneously performs multiple constraint path planning from a DMA data base and goal properties list, obstacle avoidance, and road following. Path planning and obstacle avoidance were successfully demonstrated in March 1985; road following will be demonstrated in February 1986. These results are made possible by the coupling of several procedural and knowledge-based subsystems into a modular architecture.

A fuzzy logic approach to robotic path planning with obstacle avoidance

Abstract: Robotic path planning with obstacle avoidance is considered. The main objective of the proposed approach is to reduce planning time considerably for "real-time" applications with obstacles of arbitrary configuration. The concept of a minimum required joint motion envelope is introduced to facilitate the representation of the joint kinematic solutions. Near minimum time trajectories are generated through a phase plane analysis. If the planned path is obstructed, then the obstacle geometry is approximated and a suitable projection is found in joint space. A modified path is finally determined to avoid the obstacles. Fuzzy logic is employed to incorporate uncertainty into the algorithmic procedure. Preliminary investigations have been carried out using a PUMA 560 and its associated workspace.

A review of obstacle avoidance/search sonars suitable for submersible applications

Abstract: Sonars a faisceau etroit fixe, a balayage mecanique du faisceau etroit, a comparaison de phase, a balayage lateral, a plusieurs faisceaux

Collision Avoidance Problem for a Locomotive Robot to Moving Obstacles

Abstract: 移動ロボットは, 固定された障害物のみならず, 移動する障害物に対しても衝突回避を行う必要がある.本論文は, 移動ロボットの一つの移動障害物に対する, 衝突回避問題の一解法について述べている.提案する解法は3つのステップよりなる.第一ステップは, 衝突して来る移動体の危険性を評価する手法である.第二は, 衝突して来る移動体に対して, 衝突回避経路を計画する手法である.第三は, ロボットの速度を制御する手法である.そして, また筆者らは, 提案している手法に基づく, ロボットの衝突回避行動のコンピュータシミュレーションについて示す.

Estimation Of Edge Motion Based On Local Modeling

Abstract: This paper is concerned with an original procedure which has been designed to determine moving edges. An image sequence is considered as a 3D-space (x,y,t) and a moving local 2D-edge is modeled as a small planar patch in this 3D-space. A maximum likelihood procedure enables to simultaneously detect such planar patches and estimate their orientation (i.e., spatial direction of the corresponding 2D-edge element and perpendicular component of its displacement). The computational aspect of this method merely consists of convolution operations by considering appropriate local 3D-neighborhoods. This early processing is part of a robot vision algorithm for an obstacle avoidance task, currently developed at the laboratory.

Commanding device for obstacle evading operation of unmanned vehicle

Abstract: PURPOSE: To deal flexibly with a practical processing speed and the distribution state of various obstacles by judging the necessity of obstacle evasion, and performing arithmetic operation upon occasion and putting an unmanned vehicle in evading operation. CONSTITUTION: An evasion necessity deciding device 6 finds the distance between a run course and an obstacle by using information on the run course stored in a run course storage device 2 and judges the necessity of evasion on the basis of the distance value. Further, an evading operation deciding device 7 computes and determine the distance between the obstacle and unmanned vehicle when the deciding device 6 judges that the obstacle detected by an obstacle detecting device 5 needs to be evaded. The necessary controlled variable of this evading operation is calculated by a run controller 3 to control a driving device 4 and information on the obstacle is obtained from the detecting device 5 even after the evading operation is started to judge the normalcy of last evading operation and a change in the state of the obstacle. Consequently, better evading operation is performed and the change in the state is dealt with. COPYRIGHT: (C)1987,JPO&Japio

A Pilot for a Robotic Vehicle System

Abstract: The role of an automatic pilot in an autonomous land vehicle system is to guide the vehicle along its mission path, while at the same time avoiding unexpected obstacles. We demonstrate an algorithm that accomplishes this task in real-time with the capability to generate vehicle guidance commands every 60 milliseconds. Many aspects of obstacle avoidance and path following can be shown to depend only on the current snapshots of the local work space with only a few global parameters needed. The algorithm works by finding conical-shaped usable subsets of the local work space and is motivated by the heuristic requirement of staying in sensor view of the subgoal. Our approach allows for vehicle dynamics which is often neglected in other approaches and yields smooth paths. The problem of traps inherent in potential field approaches is avoided by introducing a winding angle principle. Before field testing, the performance of the pilot was evaluated by the computer simulation of a 10-ton tracked vehicle. During recent field tests, the pilot was successful in guiding an M113 armored personnel carrier around obstacles while staying inside the path corridor.

Kinematic control and obstacle avoidance for redundant manipulators

Abstract: This paper considers the problem of steering a redundant manipulator from an initial to a final position in the work space (Cartesian space). An optimal control approach is employed, to avoid obstacles in the work space and simultaneously avoid the kinematically singular configurations throughout the trajectory.

Single Step Optimization of Feedback-Decoupled Collision Avoidance Manipulator Maneuvers

Abstract: Simultaneous robot path planning and path following is shown to be achievable in the presence of motor saturation and obstacle avoidance requirements. The discrete time algorithm derived performs one step ahead mean square optimization of commanded joint accelerations, subject to present actuator force or torque constraints and N step ahead prediction of configuration constraints.

Software Architecture Of Machine Vision For Roving Robots

Abstract: This paper presents a comprehensive approach to the design of machine vision software for roving robots and autonomous vehicles. Various techniques are proposed for solving the important problems of directional guidance, obstacle avoidance, and object identification. Artificial intelligence and knowledge-base concepts form the basis of the vision system design. The principle of texture invariance is introduced for shadow analysis and discrimination. The idea of scene layout footprints and 3-D maps for landmarks is proposed as a means of orientation determination for the guidance and navigation of roving robots and autonomous vehicles. The vision system performs three phases of visual processing: the initialization phase, the "walking" phase, and the warning phase. The visual processing and interpretation are monitored by the knowledge access and inference routine.

Computer Vision For The Guidance Of Roving Robots

Abstract: A design of computer software for machine vision of roving robots is presented. We have identified the basic requirements for the guidance and navigation of roving robots as directional guidance, obstacle avoidance, orientation determination, range finding, and object identification. To meet these requirements, we developed techniqes for safety path planning for roving robots, proposed methods for shadow identification and object discrimination, and introduced the concept of scene layout footprint and 3-D maps for landmarks. Analytical study is supported by experimental results.

FORPS: a FORTH-based production system and its application to a real-time robot control problem

Abstract: A simple yet very powerful system has been developed that merges the artificial intelligence qualities of a production system with the real-time control capabilities of FORTH. FORPS (FORTH-based Production System) offers the advantages of intelligent, rule-based control in a small package offering high speed, extensibility, and simplicity. A practical example of the system is presented in the development of an obstacle avoidance program to aid in controlling an overhead manipulator transport system. Several other potential applications to the area of control are discussed.

Kinematics mappings and robotics

Abstract: Simple kinematic mappings have been used in robotics for the specification of robot motion in obstacle avoidance problems. Different kinematic mappings have been highly developed by kinematics researchers for the design of mechanisms, focussed primarily on single degree of freedom motion. It is possible that a more general theory of kinematic mapping will unite this effort. Presented here is a survey of the theory of the kinematic mappings of planar, spherical, and spatial displacements used in mechanical design, together with examples of loci of planar and spherical displacements which satisfy a general constraint.

An intelligent systeh for an autonohous vehicle

Abstract: This paper describes an intelligent full-size autonomous vehicle system which simultaneously performs multiple constraint path planning from a DMA data base and goal properties list, obstacle avoidance, and road following. Path planning and obstacle avoidance were successfully demonstrated in March 1985; road following will be demonstrated in February 1986. These results are made possible by the coupling of several procedural and knowledge-based subsystems into a modular architecture.