Collision avoidance system with obstacles and humans to collaborative robots arms based on RGB-D data

The collaboration between humans and machines, where humans can share the same work environment without safety equipment due to the collision avoidance characteristic is one of the research topics for the Industry 4.0. This work proposes a system that acquires the space of the environment through an RGB-Depth sensor, verifies the free spaces in the created Point Cloud and executes the trajectory of the collaborative manipulator avoiding collisions. It is demonstrated a simulated environment before the system in real situations, in which the movements of pick-and-place tasks are defined, diverting from virtual obstacles with the RGB-Depth sensor. It is possible to apply this system in real situations with obstacles and humans, due to the results obtained in the simulation. The basic structure of the system is supported by the ROS software, in particular, the Movelt! and Rviz. These tools serve both for simulations and for real applications. The obtained results allow to validate the system using the algorithms PRM and RRT, chosen for being commonly used in the field of robot path planning.This work has been partially funded by Junta de Castilla y León and FEDER funds, under Research Grant No. LE028P17 and by "Ministerio de Ciencia, Innovación y Universidades" of the Kingdom of Spain through grant RTI2018-100683- B-I00.info:eu-repo/semantics/publishedVersio

Path following algorithm for highly redundant manipulators

An algorithm for path planning for highly redundant manipulators is presented in this paper. Assuming an approximated path is given by B-spline curves, path following is defined by requiring manipulator links to remain approximately tangent to these curves. The algorithm decouples manipulator links and establishes each link's position relative to the curve using a numerical approach. As a result, the whole link achieves manoeuvring around the curve. A robust propagation procedure between links is also performed, which checks every link's position and moves the links coming after the most recently moved link. These features lead to handling a huge number of degrees of freedom (DOFs) while keeping tight manoeuvring ability of highly redundant manipulators as illustrated with several examples. (C) 2003 Elsevier B.V. All rights reserved

Path planning using potential fields for highly redundant manipulators

Several aspects of the path planning problem for highly redundant manipulators are dealt with in this paper. A new method is presented for the path planning. The basic idea is to find a smooth path consisting of points close enough to each other using harmonic potential fields, and then to keep the tip of each link on these path points until the manipulator reaches the goal. The concept of master link is introduced and applied to three path planning algorithms for the smooth motion of the manipulator. A reversing procedure is included to take the manipulator to its initial position. Besides, software developed in C++ for Windows platforms is introduced. The main features of the software are to draw obstacles and manipulators on the screen, to obtain two- and three-dimensional images of potential fields and implement path planning algorithms. © 2005 Elsevier B.V. All rights reserved

The beam analysis algorithm for path planning for redundant manipulators

An algorithm for path planning for redundant manipulators is presented in this paper. The algorithm uses harmonic potential fields defined globally in W-space (work space) for both path planning and obstacle avoidance. Although paths generated by harmonic potential fields are collision free for point robots, this is not always the case for manipulators when especially tight manoeuvring is required. To enhance collision avoidance ability of redundant manipulators, the beam analysis algorithm is proposed. The algorithm sends beams along the path generated for point robots to determine virtual obstacle points where collision with obstacle is likely to occur. The potential field is then regenerated to include these virtual obstacle points. Besides, the interaction between manipulator links and the potential field is accomplished by the control points situated on only proximal ends of the links. The virtual obstacle points and selected control points allow the manipulator to achieve tight manoeuvring in W-spaces cluttered with many obstacles. The improvement in performance is also clearly indicated by a benchmark scheme that compares the algorithms by means of the complexity of the environment with respect to link lengths of redundant manipulators. Furthermore, the beam analysis algorithm readily produces safer paths for mobile robots, which does not suffer too far or too close problems. Examples are included to demonstrate these features of the algorithm. (C) 2004 Elsevier Ltd. All rights reserved.C1 Pamukkale Univ, Dept Mech Engn, TR-20017 Camlik, Denizli, Turkey

Tight Maneuvering for Path Planning of Hyper-Redundant Manipulators in Three-Dimensional Environments

An effective path-planning algorithm in three-dimensional (3D) environments based on a geometric approach for redundant/hyper-redundant manipulators are presented in this paper. The method works within confined spaces cluttered with obstacles in real-time. Using potential fields in 3D, a middle path is generated for point robots. Beams are generated tangent to the path points, which constructs a basis for preparing a collision-free path for the manipulator. Then, employing a simply control strategy without interaction between the links, the motion planning is achieved by advancing the end-effector of the manipulator through narrow terrains while keeping each link’s joints on this path until the end-effector reaches the goal. The method is simple, robust and significantly increases maneuvering ability of the manipulator in 3D environments compared to existing methods as illustrated with examples

by a single force

In this study an elastic-plastic stress analysis is carried out in a woven thermoplastic fiber-reinforced thermoplastic composite cantilever beam loaded by a constant single force at its free end. The expansion of the plastic region and the residual stress component of sigma(x) are determined for 0, 15, 30, and 45 degrees orientation angles. Yielding begins for 0 and 45 degrees orientation angles of both upper and lower surfaces of the beam at the same distances from the free end. An elastic-plastic analysis is carried out for the plastic region, which spreads both at the upper and lower surfaces. The residual stress components are obtained after releasing the external force. The distributions of the residual stress components of sigma(x) are also determined. The intensity of the residual stress components of sigma(x) is maximum at the upper or lower surfaces of the beam.C1 Pamukkale Univ, Dept Mech Engn, Fac Engn, TR-20017 Camlik, Denizli, Turkey