A motion planner for nonholonomic mobile robots

This paper considers the problem of motion planning for a car-like robot (i.e., a mobile robot with a nonholonomic constraint whose turning radius is lower-bounded). We present a fast and exact planner for our mobile robot model, based upon recursive subdivision of a collision-free path generated by a lower-level geometric planner that ignores the motion constraints. The resultant trajectory is optimized to give a path that is of near-minimal length in its homotopy class. Our claims of high speed are supported by experimental results for implementations that assume a robot moving amid polygonal obstacles. The completeness and the complexity of the algorithm are proven using an appropriate metric in the configuration space R^2 x S^1 of the robot. This metric is defined by using the length of the shortest paths in the absence of obstacles as the distance between two configurations. We prove that the new induced topology and the classical one are the same. Although we concentrate upon the car-like robot, the generalization of these techniques leads to new theoretical issues involving sub-Riemannian geometry and to practical results for nonholonomic motion planning

Sensor-based automated path guidance of a robot tool

The objective of the research is to develop a robot capability for a simultaneous measurement of the orientation (surface normal) and position of a 3-dimensional unknown object for a precise tool path guidance and control. The proposed system can guide the robot manipulator while maintaining specific orientation between the robot end-effector and the workpiece and also generate a measured geometric CAD database; The first phase involves the computer graphics simulation of an automated guidance and control of a robot tool using the proposed scheme. In the simulation, an object of known geometry is used for camera image data generation and subsequently determining the position and orientation of surface points based only on the simulated camera image information. Based on this surface geometry measurement technique, robot tool guidance and path planning algorithm is developed; The second phase involves the laboratory experiment. To demonstrate the validity of the proposed measurement method, the result of CCD image processing (grey to binary image conversion, thinning of binary image, detection of cross point, etc) and the calibration of the cameras/lighting source are performed. (Abstract shortened by UMI.)

Robotic path planning using NDT ultrasonic data for autonomous inspection

Copyright © M. Zhang et al. 2023. Robot deployed ultrasonic inspection for Non-Destructive Testing (NDT) offers several advantages including time efficiency gains, the reducing of repetitive manual workloads for operators and the enabling of inspection of environments hazardous to human health. Due to accuracy requirements, NDT robotic inspection has traditionally used the concept of digital twins for path planning activities. Recent development has sought to automate this process through visual feedback using low-cost camera sensors. However, these methods do not take into account the use of NDT data itself as part of the robot path planning process. As a consequence, poor path planning accuracy can result due to the inability of conventional cameras to capture internal defects or geometric features. This paper introduces a novel concept of using the NDT ultrasonic data as part of a robotic path planning feedback loop. Firstly, the robot is manually positioned near the start of a weld, and the ultrasonic data is collected. Next, algorithms are implemented to monitor changes in the weld geometry, to determine the robot's movement and pose based on real-time monitoring data, and to enable the robot to autonomously scan a weld with a minimum of operators input, path planning or digital twin. This is advantageous to NDT as visual sensors are unable to monitor geometric features within the weld. The ability to use the NDT data ensures the inspection continues at the optimal configuration (e.g. correct stand off and limiting probe skew), and achieves optimal path planning for NDT robots. The experimental results have shown that the tracking algorithm can effectively and accurately track defects in the sample during the ultrasonic probe detection process with an error rate within ±1 mm.This project was part of an initiative known as AEMRI (Advanced Engineering Material Research Institute which is funded by the Welsh European Funding Office (WEFO) using European Regional Development Funds (ERDF)

Path Planning for Underactuated Dubins Micro-robots Using Switching Control

In this paper, we develop an optimal path planning strategy for under-actuated Dubins micro-robots. Such robots are non-holonomic robots constrained to move along circular paths of fixed curvature clockwise or counter-clockwise. Our objective is to investigate the coverage and optimal path problems, as well as multi-robot cooperation, for a switching control scheme. Our methods are based on elementary geometry and optimal control techniques. The results in this paper show that the trajectories of micro-robots can cover the entire two-dimensional plane, and that the proposed switching control scheme allows multiple robots to cooperate. In addition, we deduce the minimum-time path under the switching control scheme by converting the robot model into the traditional Dubins vehicle model

Defining scanning trajectory for on-machine inspection using a laser-plane scanner

International audienceScan path planning for on-machine inspection in a 5-axis machine tool is still a challenge to measure part geometry in a minimum amount of time with a given scanning quality. Indeed, as the laser-plane scanner takes the place of the cutting tool, the time allocated to measurement must be reduced, but not at detrimental of the quality. In this direction, this paper proposes a method for scan path planning in a 5-axis machine tool with the control of scanning overlap. This method is an adaptation of a method dedicated to a robot that has proved its efficiency for part inspection

Can a Robot Hear the Shape and Dimensions of a Room?

© 2019 IEEE. Knowing the geometry of a space is desirable for many applications, e.g. sound source localization, sound field reproduction or auralization. In circumstances where only acoustic signals can be obtained, estimating the geometry of a room is a challenging proposition. Existing methods have been proposed to reconstruct a room from the room impulse responses (RIRs). However, the sound source and microphones must be deployed in a feasible region of the room for it to work, which is impractical when the room is unknown. This work propose to employ a robot equipped with a sound source and four acoustic sensors, to follow a proposed path planning strategy to moves around the room to collect first image sources for room geometry estimation. The strategy can effectively drives the robot from a random initial location through the room so that the room geometry is guaranteed to be revealed. Effectiveness of the proposed approach is extensively validated in a synthetic environment, where the results obtained are highly promising