Path Planning for Spatial Robots With Multiple Spherical and Cylindrical Obstacles Inside the Workspace

1992 ◽  
Author(s):  
Menq-Dar Shieh ◽  
Carl Crane ◽  
Joseph Duffy
Keyword(s):  
Path Planning ◽  
Coordinate System ◽  
Inclination Angle ◽  
Cross Sections ◽  
Computation Time ◽  
End Effector

Abstract Algorithms which can rapidly generate collision free paths for the end effector tip of a spatial 4R manipulator with multiple spherical or cylindrical obstacles inside the workspace have been successfully developed. The algorithms are based on the geometry of the manipulator workspace. The problem of guiding the spatial 4R manipulator while avoiding the obstacles is reduced to that of moving a point and at the same time avoiding rectangles in a Inclination Angle Coordinate System (IACS). The complexity of the path planning is reduced from the 3D case to the 2D case in the IACS, and the speed of generating the collision free paths is improved significantly without losing the characteristics of 3D path planning. The algorithms have been successfully implemented in a Silicon Graphics 4D-70GT workstation to verify the results. The computation time for generating 10 collision free paths with 7 spherical obstacles or 10 cylindrical obstacles inside the workspace is 1 or 2 seconds. Also, the algorithms, which are designed as interactive programs, are modified to guide a spatial T3586 robot around pipes with circular cross sections.

Investigation of Branch Accessibility with a Robotic Pruner for Pruning Apple Trees

2021 ◽  
Vol 64 (5) ◽  
pp. 1459-1474
Author(s):  
Azlan Zahid ◽  
Long He ◽  
Daeun Choi ◽  
James Schupp ◽  
Paul Heinemann
Keyword(s):  
Path Planning ◽  
Free Path ◽  
Path Length ◽  
Computation Time ◽  
Tree Canopy ◽  
Random Tree ◽  
Target Point ◽  
List Type ◽  
Apple Trees ◽  
End Effector

HighlightsA branch accessibility simulation was performed for robotic pruning of apple trees.A virtual tree environment was established using a kinematic manipulator model and an obstacle model.Rapidly-exploring random tree (RRT) was combined with smoothing and optimization for improved path planning.Effects on RRT path planning of the approach angle of the end-effector and cutter orientation at the target were studied.Abstract. Robotic pruning is a potential solution to reduce orchard labor and associated costs. Collision-free path planning of the manipulator is essential for successful robotic pruning. This simulation study investigated the collision-free branch accessibility of a six rotational (6R) degrees of freedom (DoF) robotic manipulator with a shear cutter end-effector. A virtual environment with a simplified tall spindle tree canopy was established in MATLAB. An obstacle-avoidance algorithm, rapidly-exploring random tree (RRT), was implemented for establishing collision-free paths to reach the target pruning points. In addition, path smoothing and optimization algorithms were used to reduce the path length and calculate the optimized path. Two series of simulations were conducted: (1) performance and comparison of the RRT algorithm with and without smoothing and optimization, and (2) performance of collision-free path planning considering different approach poses of the end-effector relative to the target branch. The simulations showed that the RRT algorithm successfully avoided obstacles and allowed the manipulator to reach the target point with 23 s average path finding time. The RRT path length was reduced by about 28% with smoothing and by 25% with optimization. The RRT smoothing algorithm generated the shortest path lengths but required about 1 to 3 s of additional computation time. The lowest coefficient of variation and standard deviation values were found for the optimization method, which confirmed the repeatability of the method. Considering the different end-effector approach poses, the simulations suggested that successfully finding a collision-free path was possible for branches with no existing path using the ideal (perpendicular cutter) approach pose. This study provides a foundation for future work on the development of robotic pruning systems. Keywords: Agricultural robotics, Collision-free path, Manipulator, Path planning, Robotic pruning, Virtual tree environment.

scholarly journals Improving ozone profile retrieval from spaceborne UV backscatter spectrometers using convergence behaviour diagnostics

2010 ◽  
Vol 3 (6) ◽  
pp. 1555-1568 ◽  
Author(s):  
B. Mijling ◽  
O. N. E. Tuinder ◽  
R. F. van Oss ◽  
R. J. van der A
Keyword(s):  
Cross Sections ◽  
A Priori ◽  
Computation Time ◽  
External Input ◽  
Computational Time ◽  
Ozone Profile ◽  
Global Performance ◽  
Convergence Behaviour ◽  
Low Cloud ◽  
Average Computation Time

Abstract. The Ozone Profile Algorithm (OPERA), developed at KNMI, retrieves the vertical ozone distribution from nadir spectral satellite measurements of back scattered sunlight in the ultraviolet and visible wavelength range. To produce consistent global datasets the algorithm needs to have good global performance, while short computation time facilitates the use of the algorithm in near real time applications. To test the global performance of the algorithm we look at the convergence behaviour as diagnostic tool of the ozone profile retrievals from the GOME instrument (on board ERS-2) for February and October 1998. In this way, we uncover different classes of retrieval problems, related to the South Atlantic Anomaly, low cloud fractions over deserts, desert dust outflow over the ocean, and the intertropical convergence zone. The influence of the first guess and the external input data including the ozone cross-sections and the ozone climatologies on the retrieval performance is also investigated. By using a priori ozone profiles which are selected on the expected total ozone column, retrieval problems due to anomalous ozone distributions (such as in the ozone hole) can be avoided. By applying the algorithm adaptations the convergence statistics improve considerably, not only increasing the number of successful retrievals, but also reducing the average computation time, due to less iteration steps per retrieval. For February 1998, non-convergence was brought down from 10.7% to 2.1%, while the mean number of iteration steps (which dominates the computational time) dropped 26% from 5.11 to 3.79.

scholarly journals Multi-robot path planning using an improved self-adaptive particle swarm optimization

2020 ◽  
Vol 17 (5) ◽  
pp. 172988142093615
Author(s):  
Biwei Tang ◽  
Kui Xiang ◽  
Muye Pang ◽  
Zhu Zhanxia
Keyword(s):  
Particle Swarm Optimization ◽  
Path Planning ◽  
Evolutionary Game ◽  
Particle Swarm ◽  
Computation Time ◽  
Robot Path Planning ◽  
Swarm Optimization ◽  
Robot Path ◽  
Self Adaptive ◽  
Multi Robot

Path planning is of great significance in motion planning and cooperative navigation of multiple robots. Nevertheless, because of its high complexity and nondeterministic polynomial time hard nature, efficiently tackling with the issue of multi-robot path planning remains greatly challenging. To this end, enhancing a coevolution mechanism and an improved particle swarm optimization (PSO) algorithm, this article presents a coevolution-based particle swarm optimization method to cope with the multi-robot path planning issue. Attempting to well adjust the global and local search abilities and address the stagnation issue of particle swarm optimization, the proposed particle swarm optimization enhances a widely used standard particle swarm optimization algorithm with the evolutionary game theory, in which a novel self-adaptive strategy is proposed to update the three main control parameters of particles. Since the convergence of particle swarm optimization significantly influences its optimization efficiency, the convergence of the proposed particle swarm optimization is analytically investigated and a parameter selection rule, sufficiently guaranteeing the convergence of this particle swarm optimization, is provided in this article. The performance of the proposed planning method is verified through different scenarios both in single-robot and in multi-robot path planning problems. The numerical simulation results reveal that, compared to its contenders, the proposed method is highly promising with respect to the path optimality. Also, the computation time of the proposed method is comparable with those of its peers.

MATHEMATICAL MODEL FOR CHIP GEOMETRY CALCULATION IN FIVE-AXIS MILLING

2015 ◽  
Vol 77 (23) ◽  
Author(s):  
Hendriko Hendriko
Keyword(s):  
Coordinate System ◽  
Inclination Angle ◽  
Mapping Technique ◽  
Depth Of Cut ◽  
Work Piece ◽  
Primary Input ◽  
Proposed Model ◽  
Engagement Angle ◽  
Scheduling Method ◽  
Five Axis

This paper presents the method to calculate the geometries of instantaneous chip in five-axis milling. The inclination angle changes in between two consecutive CC-points were taken into account in the calculation. In the first stage, the engagement angle, the axial depth of cut and cut width were determined through the mapping technique. The engagement point of the Work piece Coordinate System (WCS) was mapped to a Tool Coordinate System (TCS). In the second stage, the engagement angle and depth of cut, which were defined in the first stage were then used as a primary input to obtain the cut thickness and cut width. Two simulation tests have been presented to verify the ability of the proposed model to predict the cut geometry. The first tests revealed that the inclination angle makes the size of the cut thickness and cut width fluctuate. The cut width increased when the tool inclination angle increased. For the cut thickness, its magnitude was influenced by two effects, the orientation effect and the tooth path effect. The final result was a compromise between these two effects. In the second simulation test, the proposed model was successfully implemented to support the feedrate scheduling method.

3D Curve Generation Using Spherical Polar Piecewise Interpolation in CAD and CAM

2020 ◽  
Vol 896 ◽  
pp. 224-228
Author(s):  
Mihai Dupac
Keyword(s):  
Path Planning ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Trajectory Planning ◽  
Robot Arm ◽  
Polar Plane ◽  
Spherical Coordinate ◽  
Manufacturing Efficiency ◽  
Planning Approach ◽  
Design And Manufacturing

In this paper a newly 3D path planning approach and curve generation for design and manufacturing efficiency is considered. The 3D path is generated by a combination of piecewise interpolating curves - along a given number of via-points - created via a spherical coordinate system specified by the polar angles, radial distances and the associated azimuthal angles. Each piecewise interpolating curve is constructed using Hermite polar interpolation in the projective polar plane and the rotating azimuthal plane. To verify the proposed approach, numerical simulations for the generation of a helix design, a 4 and 6 leaf design and a trajectory planning of a picking robot arm are conducted.

Optimal Continuous Path Planning for Seven-Degrees-of-Freedom Robots

1986 ◽  
Vol 108 (3) ◽  
pp. 213-218 ◽  
Author(s):  
B. Benhabib ◽  
A. A. Goldenberg ◽  
R. G. Fenton
Keyword(s):  
Path Planning ◽  
Trajectory Planning ◽  
Degrees Of Freedom ◽  
Polynomial Interpolation ◽  
Continuous Path ◽  
End Effector ◽  
Joint Level ◽  
Redundant Robots ◽  
Planning And Control ◽  
Optimization Search

The paper addresses the problem of end effector trajectory planning and control of seven degrees of freedom (DOF) kinematically redundant robots. An off-line optimal continuous path planning method is developed for on-line control at joint level. The specified end effector path is approximated by a set of location nodes selected on the desired path. The motion control of the robot is provided by cubic polynomial interpolation at joint level. The proposed approach to trajectory planning of kinematically redundant robots consists of obtaining an optimal set of nodes which guarantees minimum deviation from the desired Cartesian path. The redundant DOF of the robot is used as a constrained variable in the optimization search. The method is illustrated in an example.

Sign in / Sign up

Export Citation Format

Share Document