scholarly journals PATH PLACEMENT OPTIMIZATION OF MANIPULATORS BASED ON ENERGY CONSUMPTION: APPLICATION TO THE ORTHOGLIDE 3-AXIS

2009 ◽  
Vol 33 (3) ◽  
pp. 523-541 ◽  
Author(s):  
Raza Ur-Rehman ◽  
Stéphane Caro ◽  
Damien Chablat ◽  
Philippe Wenger

This paper deals with the optimal path placement for a manipulator based on energy consumption. It proposes a methodology to determine the optimal location of a given test path within the workspace of a manipulator with minimal electric energy used by the actuators while taking into account the geometric, kinematic and dynamic constraints. The proposed methodology is applied to the Orthoglide 3-axis, a three-degree-of-freedom translational parallel kinematic machine (PKM), as an illustrative example.

Author(s):  
Xuan Luo ◽  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Jie Li

5-Degree-of-freedom parallel kinematic machine tools are always attractive in manufacturing industry due to the ability of five-axis machining with high stiffness/mass ratio and flexibility. In this article, error modeling and sensitivity analysis of a novel 5-degree-of-freedom parallel kinematic machine tool are discussed for its accuracy issues. An error modeling method based on screw theory is applied to each limb, and then the error model of the parallel kinematic machine tool is established and the error mapping Jacobian matrix of 53 geometric errors is derived. Considering that geometric errors exert both impacts on value and direction of the end-effector’s pose error, a set of sensitivity indices and an easy routine for sensitivity analysis are proposed according to the error mapping Jacobian matrix. On this basis, 10 vital errors and 10 trivial errors are identified over the prescribed workspace. To validate the effects of sensitivity analysis, several numerical simulations of accuracy design are conducted, and three-dimensional model assemblies with relevant geometric errors are established as well. The simulations exhibit maximal −0.10% and 0.34% improvements of the position and orientation errors, respectively, after modifying 10 trivial errors, while minimal 65.56% and 55.17% improvements of the position and orientation errors, respectively, after modifying 10 vital errors. Besides the assembly reveals an output pose error of (0.0134 mm, 0.0020 rad) with only trivial errors, while (2.0338 mm, 0.0048 rad) with only vital errors. In consequence, both results of simulations and assemblies validate the correctness of the sensitivity analysis. Moreover, this procedure can be extended to any other parallel kinematic mechanisms easily.


2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Arta Alagheband ◽  
Masih Mahmoodi ◽  
James K. Mills ◽  
Beno Benhabib

Parallel kinematic mechanisms (PKMs) provide high stiffness and compact structures that are suitable for a large number of applications, including 5-axis milling. This paper presents a new pentapod-based PKM with an additional redundant degree-of-freedom (DOF) capable of reaching platform tilt angles of at least 90 deg over a large workspace. The proposed new PKM has a 6DOF 4 × SPRR + 1 × PSPR architecture. It is compared herein to Metrom® Pentapod as well as to several other pertinent PKMs in terms of workspace and dynamic stiffness. It is shown that the proposed mechanism can yield a tangibly larger workspace volume, when compared to those PKMs, while maintaining its high stiffness characteristics.


2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shoubao Su ◽  
Wei Zhao ◽  
Chishe Wang

Multirobot motion planning is always one of the critical techniques in edge intelligent systems, which involve a variety of algorithms, such as map modeling, path search, and trajectory optimization and smoothing. To overcome the slow running speed and imbalance of energy consumption, a swarm intelligence solution based on parallel computing is proposed to plan motion paths for multirobot with many task nodes in a complex scene that have multiple irregularly-shaped obstacles, which objective is to find a smooth trajectory under the constraints of the shortest total distance and the energy-balanced consumption for all robots to travel between nodes. In a practical scenario, the imbalance of task allocation will inevitably lead to some robots stopping on the way. Thus, we firstly model a gridded scene as a weighted MTSP (multitraveling salesman problem) in which the weights are the energies of obstacle constraints and path length. Then, a hybridization of particle swarm and ant colony optimization (GPSO-AC) based on a platform of Compute Unified Device Architecture (CUDA) is presented to find the optimal path for the weighted MTSPs. Next, we improve the A ∗ algorithm to generate a weighted obstacle avoidance path on the gridded map, but there are still many sharp turns on it. Therefore, an improved smooth grid path algorithm is proposed by integrating the dynamic constraints in this paper to optimize the trajectory smoothly, to be more in line with the law of robot motion, which can more realistically simulate the multirobot in a real scene. Finally, experimental comparisons with other methods on the designed platform of GPUs demonstrate the applicability of the proposed algorithm in different scenarios, and our method strikes a good balance between energy consumption and optimality, with significantly faster and better performance than other considered approaches, and the effects of the adjustment coefficient q on the performance of the algorithm are also discussed in the experiments.


2005 ◽  
Vol 128 (2) ◽  
pp. 392-402 ◽  
Author(s):  
Stéphane Caro ◽  
Philippe Wenger ◽  
Fouad Bennis ◽  
Damien Chablat

In this paper, two complementary methods are introduced to analyze the sensitivity of a three-degree-of-freedom (3-DOF) translational parallel kinematic machine (PKM) with orthogonal linear joints: the Orthoglide. Although these methods are applied to a particular PKM, they can be readily applied to 3-DOF Delta-Linear PKM such as ones with their linear joints parallel instead of orthogonal. On the one hand, a linkage kinematic analysis method is proposed to have a rough idea of the influence of the length variations of the manipulator on the location of its end-effector. On the other hand, a differential vector method is used to study the influence of the length and angular variations in the parts of the manipulator on the position and orientation of its end-effector. Besides, this method takes into account the variations in the parallelograms. It turns out that variations in the design parameters of the same type from one leg to another have the same effect on the position of the end-effector. Moreover, the sensitivity of its pose to geometric variations is a minimum in the kinematic isotropic configuration of the manipulator. On the contrary, this sensitivity approaches its maximum close to the kinematic singular configurations of the manipulator.


2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Jinsong Wang ◽  
Jun Wu ◽  
Liping Wang ◽  
Tiemin Li

In the homing process of a regular parallel kinematic machine (PKM), all servoaxes are independently driven to return to their homing positions. However, in a redundantly actuated PKM, the redundant limb will interfere with other servoaxes. This paper concerns the homing of a redundant four degree of freedom PKM, and an assistant homing strategy is proposed for the machine to pass the singular configuration in the homing process. After the assistant homing is finished, the other four nonredundant axes are driven to return to their home positions independently. Based on the kinematic model and the length of the redundant limb, the condition that the redundant limb performs assistant homing is determined. The homing strategy is incorporated into the numerical control system of the studied PKM. The test shows that the homing strategy is effective, and it can also be useful for other kinds of redundantly actuated PKMs.


2012 ◽  
Vol 7 (3) ◽  
pp. 23-32 ◽  
Author(s):  
Miloslav Bagoňa ◽  
Dušan Katunský ◽  
Martin Lopušniak ◽  
Marián Vertaľ

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