Parallel path planning with temporal parametrization (original) (raw)

Reactive approach to on-line path planning for robot manipulators in dynamic environments

Robotica, 2002

This paper describes a new approach to path planning of robot manipulators with many degrees of freedom. It is designed for on-line motion in dynamic and unpredictable environments. The robots react to moving obstacles using a local and reactive algorithm restricted to a subset of its configuration space. The lack of a long-term view of local algorithms (local minima problems) is solved using an off-line pre-planning stage that chooses the subset of the configuration space that minimises the probability of not finding collision free paths. The approach is implemented and tested on a system of three Scorbot-er IX five link robots.

Near-time optimal robot motion planning foe on-line applications

Journal of Robotic Systems, 1995

Solving current formulations of the time-optimal point-to-point motion problem for robotic manipulators is a computationally intensive task. Thus, most existing solutions are not suitable for on-line motion planning applications, such as the interception of moving targets, where time-optimality of the motion is advantageous. A novel technique is proposed in this article that separates the time-optimal point-to-point motion problem into the following two sub-problems: (1) selection of a near-time-optimal path between the two endpoints, and (2) generation of time-optimal motion along the selected path (i.e., constrained continuous path motion). Although our approach uses known path-constrained time-optimal-motion algorithms for the second sub-problem, a new method is proposed for the selection of near-time-optimal paths. Based on a study of the characteristics of global-time-optimal paths, the near-optimal path is selected as a minimum-curvature joint spline, tangent to one of the manipulator's acceleration directions at the start point, and tangent to the required manipulator velocity direction at the end point. The algorithm for determining the overall nearoptimal path is described herein, along with an example. Simulation test results and computation-time studies indicate that the proposed method is suitable for on-line motion planning applications. 0 2995 john Wiley 6 Sons, Inc.

Online via-points trajectory generation for reactive manipulations

2014 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2014

In various circumstances, such as human-robot interactions and industrial processes, planning at trajectory level is very useful to produce better movement. In this paper we present a near time optimal approach to plan a trajectory joining via points in real time for robot manipulators. To limit the speed variation, the path is smoothed around via-points in a limited area. The concept of online trajectory generation enables systems to react instantaneously at control level to unforeseen events. Simulation and real-world experimental results carried out on a KUKA LightWeight Robot arm are presented.

Parallel Robot Motion Planning in a Dynamic Environment

1992

In order to achieve fast motion planning for a robot we have chosen the genetic algorithms for the following reasons: they are well adapted to search for solutions in high dimensionality search space. The algorithm can be used without reduction of its efficiency for arms with more than six degree of freedom, they are very tolerant to the form of the function to optimize, for instance these functions do not need to be neither differentiable or continuous. They make no assumptions about the problem space that they are searching. We are using them to solve other optimization problems: graph partitioning, quadratic assignment, ... they are easy to implement on massively parallel distributed memory architectures. The parallel algorithm proposed achieve near-linear speed-up.

Comparative analysis of collision-free path-planning methods for multi-manipulator systems

Robotica, 2006

Motion planning for manipulators with many degrees of freedom is a complex task. The research in this area has been mostly restricted to static environments. This paper presents a comparative analysis of three reactive on-line path-planning methods for manipulators: the elastic-strip, strategy-based and potential field methods. Both the elastic-strip method [O. Brock and O. Khatib, “Elastic strips: A framework for integrated planning and execution,” Int. Symp. Exp. Robot. 245–254 (1999)] and the potential field method [O. Khatib, “Real-time obstacle avoidance for manipulators and mobile robots,” Int. J. Robot. Res.5(1), 90–98 (1986)] have been adapted by the authors to the problem at hand related to our multi-manipulator system (MMS) (three manipulators with five degrees of freedom each). Strategy-based method is an original contribution by the authors [M. Mediavilla, J. L. González, J. C. Fraile and J. R. Perán, “Reactive approach to on-line path planning for robot manipulators in ...

An efficient local approach for the path generation of robot manipulators

Journal of Robotic Systems - J ROBOTIC SYST, 1990

In this article an efficient local approach for the path generation of robot manipulators is presented. The approach is based on formulating a simple nonlinear programming problem. This problem is considered as a minimization of energy with given robot kinematics and subject to the robot requirements and a singularities avoidance constraint. From this formulation a closed form solution is derived which has the properties that allows to pursue both singularities and obstacle avoidance simultaneously; and that it can incorporate global information. These properties enable the accomplishment of the important task that while a specified trajectory in the operational space can be closely followed, also a desired joint configuration can be attained accurately at a given time. Although the proposed approach is primarily developed for redundant manipulators, its application to nonredundant manipulators is examplified by considering a particular commercial manipulator.

Robot Motion Planning in Dynamic Environments

Springer eBooks, 1996

This paper presents a new sensor-based online method for generating collision-free near-optimal paths for mobile robots pursuing a moving target amidst dynamic and static obstacles. At each iteration, first the set of all collision-free directions are calculated using velocity vectors of the robot relative to each obstacle and target, forming the Directive Circle (DC), which is a novel concept. Then, a direction close to the shortest path to the target is selected from feasible directions in DC. The DC prevents the robot from being trapped in deadlocks or local minima. It is assumed that the target's velocity is known, while the speeds of dynamic obstacles, as well as the locations of static obstacles, are to be calculated online. Extensive simulations and experimental results demonstrated the efficiency of the proposed method and its success in coping with complex environments and obstacles.