Kinematics and Path Planning of a Six-Degrees-of-Freedom Robot Manipulator

Author(s):  
Carlos Mondragon ◽  
Reza Fotouhi

This paper introduces a strategy to accomplish pick-and-place operations for a six-degrees-of-freedom (6-DOF) robotic arm attached to a wheeled mobile robot. This research work is part of a bigger project in developing a robotic-assisted nursing to be used in medical settings. The significance of this project relies on the increasing demand for elderly and disabled skilled care assistance which nowadays has become insufficient. Several methods were implemented to make a 6-DOF manipulator capable of performing pick-and-place operations. This paper presents an approach for solving the inverse kinematics problem and planning collision-free paths. An Iterative Inverse Kinematics method (IIK) was introduced to find multiple configurations for the manipulator along a given path. The IIK method takes advantage of a specific geometric characteristic of the manipulator, in which several joints share a common plane. Ten different scenarios with different number and pattern of obstacles were used to verify the efficiency of a path planning algorithm introduced here. Other methods, also implemented in the current project, which describe the manipulator and its capabilities, are presented elsewhere [1]. Overall results confirmed the efficiency of the implemented methods for performing pick-and-place operations for a 6-DOF manipulator.

Robotica ◽  
1997 ◽  
Vol 15 (2) ◽  
pp. 213-224 ◽  
Author(s):  
Andreas C. Nearchou ◽  
Nikos A. Aspragathos

In some daily tasks, such as pick and place, the robot is requested to reach with its hand tip a desired target location while it is operating in its environment. Such tasks become more complex in environments cluttered with obstacles, since the constraint for collision-free movement must be also taken into account. This paper presents a new technique based on genetic algorithms (GAs) to solve the path planning problem of articulated redundant robot manipulators. The efficiency of the proposed GA is demonstrated through multiple experiments carried out on several robots with redundant degrees-of-freedom. Finally, the computational complexity of the proposed solution is estimated, in the worst case.


Author(s):  
Jie Zhong ◽  
Tao Wang ◽  
Lianglun Cheng

AbstractIn actual welding scenarios, an effective path planner is needed to find a collision-free path in the configuration space for the welding manipulator with obstacles around. However, as a state-of-the-art method, the sampling-based planner only satisfies the probability completeness and its computational complexity is sensitive with state dimension. In this paper, we propose a path planner for welding manipulators based on deep reinforcement learning for solving path planning problems in high-dimensional continuous state and action spaces. Compared with the sampling-based method, it is more robust and is less sensitive with state dimension. In detail, to improve the learning efficiency, we introduce the inverse kinematics module to provide prior knowledge while a gain module is also designed to avoid the local optimal policy, we integrate them into the training algorithm. To evaluate our proposed planning algorithm in multiple dimensions, we conducted multiple sets of path planning experiments for welding manipulators. The results show that our method not only improves the convergence performance but also is superior in terms of optimality and robustness of planning compared with most other planning algorithms.


Author(s):  
I Postlethwaite ◽  
A Bartoszewicz

In this paper, an application of a non-linear H∞ control law for an industrial robot manipulator is presented. Control of the manipulator motion is formulated into a non-linear H∞ optimization problem, namely optimal tracking performance in the presence of modelling uncertainties and external disturbances. Analytical solutions for this problem are implemented on a real robot. The robot under consideration is the six-degrees-of-freedom GEC Tetrabot. Investigations are made into the selection of weights for the H∞ controller and it is shown how different selections of weights affect the Tetrabot performance. The authors believe this to be the first robotic application of nonlinear H∞ control. Comparisons of the proposed control strategy with conventional proportional-derivative and proportional-integral-derivative controllers show favourable performance of the Tetrabot under the new non-linear H∞ control scheme.


Robotica ◽  
2009 ◽  
Vol 28 (4) ◽  
pp. 477-491 ◽  
Author(s):  
Shital S. Chiddarwar ◽  
N. Ramesh Babu

SUMMARYIn this paper, a decoupled offline path planning approach for determining the collision-free path of end effectors of multiple robots involved in coordinated manipulation is proposed. The proposed approach for decoupled path planning is a two-phase approach in which the path for coordinated manipulation is generated with a coupled interaction between collision checking and path planning techniques. Collision checking is done by modelling the links and environment of robot using swept sphere volume technique and utilizing minimum distance heuristic for interference check. While determining the path of the end effector of robots involved in coordinated manipulation, the obstacles present in the workspace are considered as static obstacles and the links of the robots are viewed as dynamic obstacles by the other robot. Coordination is done in offline mode by implementing replanning strategy which adopts incremental A* algorithm for searching the collision-free path. The effectiveness of proposed decoupled approach is demonstrated by considering two examples having multiple six degrees of freedom robots operating in 3D work cell environment with certain static obstacles.


Author(s):  
Patricia Ben-Horin (Dombiak) ◽  
Moshe Shoham ◽  
Gershon Grossman

Abstract A new structure of a six degrees-of-freedom robot is described in this paper. The robot presents two new features: three inflatable links that constitute the robot structure and parallel robot architecture with large workspace. These features result in a lightweight and easy to deploy robot. The structure, kinematics and path planning of the experimental robot are presented.


2020 ◽  
Vol 17 (3) ◽  
pp. 172988142092004
Author(s):  
Yong-Lin Kuo ◽  
Chun-Chen Lin ◽  
Zheng-Ting Lin

This article presents a dual-optimization trajectory planning algorithm, which consists of the optimal path planning and the optimal motion profile planning for robot manipulators, where the path planning is based on parametric curves. In path planning, a virtual-knot interpolation is proposed for the paths required to pass through all control points, so the common curves, such as Bézier curves and B-splines, can be incorporated into it. Besides, an optimal B-spline is proposed to generate a smoother and shorter path, and this scheme is especially suitable for closed paths. In motion profile planning, a generalized formulation of time-optimal velocity profiles is proposed, which can be implemented to any types of motion profiles with equality and inequality constraints. Also, a multisegment cubic velocity profile is proposed by solving a multiobjective optimization problem. Furthermore, a case study of a dispensing robot is investigated through the proposed dual-optimization algorithm applied to numerical simulations and experimental work.


1992 ◽  
Vol 4 (3) ◽  
pp. 210-217
Author(s):  
Toshio Tsuji ◽  
◽  
Koji Ito ◽  

This paper proposes a collision-free path planning algorithm in the task space based on virtual arms. The virtual arm has the same kinematic structure as the actual arm except that its end-point is located at the joint or link of the actual arm. Therefore, the configuration of the actual arm can be represented as a set of end-points of the virtual arms, and the path planning for multi-joint manipulators can be performed only in the task space. Our method adopts a hierarchical strategy which consists of the global level, the intermediate level, and the local level. The global level plans the collision-free endpoint trajectory of the actual arm based on the global representation of the task space. The intermediate level generates the subgoals for the actual and virtual endpoints based on the current positions and the actual endpoint trajectory specified by the global level. The local level moves each end-point to the corresponding subgoal, avoiding the close obstacles based on the local informations of the task space. The effectiveness of the method is verified by computer simulations using a planar manipulator with redundant joint degrees of freedom.


Author(s):  
Carlos Mondragon ◽  
Reza Fotouhi

This research work is to control motion of a manipulator attached to a mobile robot for pick-and-place operations; this is part of a bigger project in developing a robotic-assisted nursing to be used in medical settings. In this paper a strategy to accomplish pick-and-place operations, using a six degree-of-freedom robotic arm, is presented. Such operations are completed by creating a collision-free path to move an object from an initial to a final position. The collision-free path is planned by considering the entire workspace of the manipulator. The workspace is defined as the subtraction of the stationary objects and the robot volumes from all of the possible reachable points of the robotic arm. Once the path is planned, the kinematics of the manipulator is considered. Although this project can be applied into a wide range of applications, it is mainly intended to be used for medical robotic assistance. Simulation results for several different paths are presented. The simulation results were verified with experimental results, although not shown here.


Robotica ◽  
2008 ◽  
Vol 26 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Hyeung-Sik Choi ◽  
Gyu-Deuk Hwang ◽  
Sam-Sang You

SUMMARYThis paper presents analysis and experimental verifications of a new robot manipulator with five degrees of freedom developed for the buffing operation of shoes. First, the forward and inverse kinematics are analyzed. Next, an analytic closed-form solution is rigorously derived for the joint angles corresponding to the position and orientation of the end-effector in Cartesian coordinates. A control system, including input/output interfaces and the related electronic system, is designed for the control of the mechanical structure of the buffing robot. Then, peripheral systems integrated with the conveyer, transfer device, and fixture device are designed for the sequential buffing process of shoes. Also, a graphic user interface (GUI) program including the forward/inverse kinematics, control algorithm, and communication program to interact the robot with the peripheral systems is developed by using visual C++ language. A new flexible toolholder (FTH) is proposed to compensate for the excessive applied force between deburring tools and shoes. Finally, the test results are provided to demonstrate the effectiveness of the proposed scheme.


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