Model-based joint and task space control strategies for a kinematically redundant parallel manipulator

Robotica ◽  
2021 ◽  
pp. 1-17
Author(s):  
João Vitor de Carvalho Fontes ◽  
Fernanda Thaís Colombo ◽  
Natássya Barlate Floro da Silva ◽  
Maíra Martins da Silva
Keyword(s):  
Parallel Manipulator ◽  
Control Strategies ◽  
Parallel Manipulators ◽  
Torque Control ◽  
Redundancy Resolution ◽  
Task Space ◽  
Kinematic Redundancy ◽  
Model Based ◽  
The Impact ◽  
Computed Torque

Abstract One alternative to overcome the presence of singularities within Parallel Manipulators’ workspace is kinematic redundancy. This design alternative can be realized by adding an extra active joint to a kinematic chain. Due to this addition, the IKM presents an infinite number of solutions requiring a redundancy resolution scheme. Moreover, Parallel Manipulators’ control may require complex strategies due to their coupled and complex dynamic and kinematic relations. In this work, a model-free, a joint space computed torque, and a hybrid joint-task-space computed torque control strategies are experimentally compared for a kinematically redundant parallel manipulator. The latter is a novel strategy that requires the measurement of the end-effector’s pose, which is performed by an eye-to-hand limited frame rate camera. The impact of up to three kinematic redundancy levels is also experimentally evaluated using prepositioning and ongoing positioning redundancy resolution schemes. The data are assessed by evaluating a prescribed trajectory executed using a planar kinematically redundant parallel manipulator. These results indicate that kinematic redundancy can not only be used as an alternative design for reducing the presence of singular regions, as claimed in the literature, but also be used along with model-based control strategies for improving dynamic performance and accuracy of parallel manipulators.

scholarly journals Mechatronic Model Based Computed Torque Control of a Parallel Manipulator

10.5772/5650 ◽  
2008 ◽  
Vol 5 (1) ◽  
pp. 14 ◽  
Author(s):  
Zhiyong Yang ◽  
Jiang Wu ◽  
Jiangping Mei ◽  
Jian Gao ◽  
Tian Huang
Keyword(s):  
Parallel Manipulator ◽  
Torque Control ◽  
Model Based ◽  
Computed Torque Control ◽  
Computed Torque

A Survey on Control of Parallel Manipulator

2007 ◽  
Vol 339 ◽  
pp. 307-313 ◽  
Author(s):  
J.F. He ◽  
H.Z. Jiang ◽  
D.C. Cong ◽  
Zheng Mao Ye ◽  
Jun Wei Han
Keyword(s):  
Control Strategies ◽  
Parallel Manipulators ◽  
Physical Structure ◽  
Extensive Study ◽  
Torque Control ◽  
Serial Manipulators ◽  
Advanced Control ◽  
And Performance ◽  
Computed Torque ◽  
Structure Properties

Based on extensive study on literatures of control of parallel manipulators and serial manipulators, control strategies such as computed torque control, PD+ control, PD with feedforward compensation, nonlinear adaptive control are classified into two categories: model-based control and performance-based control. Besides, as advanced control strategies, robust control and passivity-based control for the parallel manipulators are also introduced. Comparative study in view of computation burden and tracking performance are performed. It turned out that the physical structure properties of parallel manipulators’ dynamics are similar with that of serial ones, and this constitutes a common foundation for the two kinds of manipulators to develop together that control design of parallel manipulators can start with ever established control methods of serial manipulators.

Adaptive computed torque control for a parallel manipulator with redundant actuation

Robotica ◽  
2011 ◽  
Vol 30 (3) ◽  
pp. 457-466 ◽  
Author(s):  
Wei-Wei Shang ◽  
Shuang Cong ◽  
Yuan Ge
Keyword(s):  
Dynamic Model ◽  
Trajectory Tracking ◽  
Parallel Manipulator ◽  
Adaptive Dynamics ◽  
Tracking Error ◽  
Torque Control ◽  
Redundant Actuation ◽  
Task Space ◽  
Barbalat’S Lemma ◽  
Computed Torque

SUMMARYAn adaptive computed torque (ACT) controller in the task space is proposed for the trajectory tracking of a parallel manipulator with redundant actuation. The dynamic model, including the active joint friction, is established in the task space for the parallel manipulator, and the linear parameterization expression with respect to the dynamic and friction parameters is formulated. On the basis of the dynamic model, a new control law, which contains adaptive dynamics compensation, friction compensation, and tracking error elimination terms, is designed. After defining the state-space model of the error system, the parameter adaptation law is derived by using the Lyapunov method, and the convergence of the tracking error and the error rate is proved by using the Barbalat's lemma. The ACT controller is implemented in the trajectory tracking experiments of an actual 2-DOF parallel manipulator with redundant actuation, and the experiment results are compared with the computed torque controller.

A New Control Approach to Nonlinear Systems Undergoing Changes in a System Parameter

2000 ◽  
Author(s):  
Hyuk C. Nho ◽  
Peter Meckl
Keyword(s):  
Neural Network ◽  
Fuzzy Logic ◽  
Sudden Change ◽  
Torque Control ◽  
Tracking Performance ◽  
Control Architecture ◽  
Model Based ◽  
Payload Uncertainty ◽  
Payload Mass ◽  
Computed Torque

Abstract Conventional model-based computed torque control fails to produce good trajectory tracking performance in the presence of payload uncertainty and modeling error. The problem is how to provide accurate dynamics information to the controller. A new control architecture that incorporates a neural network, fuzzy logic and a simple proportional-derivative (PD) controller is proposed to control an articulated robot carrying a variable payload. A feedforward (multilayer) neural network is trained off-line to capture the nonlinear inverse dynamics of the system. The network is placed in the feedforward path to minimize tracking error. The network receives the same input signals as conventional computed torque as well as the payload mass estimate, which comes from a fuzzy logic mass estimator. The fuzzy logic, trained off-line to optimize the membership function, is developed to estimate the changing payload mass. The fuzzy logic estimator is based on joint acceleration error to improve the speed of detection and estimation of payload mass change. The effectiveness of the proposed architecture is demonstrated by experiment on a two-link planar manipulator with changing payload mass. Experiment results show that this control architecture achieves excellent tracking performance in the presence of payload uncertainty. The results of the control architecture are also compared with those of a model-based control architecture. This approach can be employed in any nonlinear mechanical system with a sudden change in a parameter.

DYNAMICS AND IMPROVED COMPUTED TORQUE CONTROL OF A NOVEL MEDICAL PARALLEL MANIPULATOR: APPLIED TO CHEST COMPRESSIONS TO ASSIST IN CARDIOPULMONARY RESUSCITATION

2015 ◽  
Vol 15 (04) ◽  
pp. 1550051 ◽  
Author(s):  
MOHSEN ASGARI ◽  
MAHDI A. ARDESTANI
Keyword(s):  
Cardiopulmonary Resuscitation ◽  
Fuzzy Inference ◽  
Virtual Work ◽  
Parallel Manipulators ◽  
Torque Control ◽  
Chest Compressions ◽  
Inverse Dynamic ◽  
Inference System ◽  
Novel Structure ◽  
Computed Torque

In cardiopulmonary resuscitation (CPR), in practice, the rescuer usually uses two hands to perform the action of chest compressions. During chest compressions action, the two arms of the rescuer actually constitute a parallel mechanism. Inspired by this performance, this paper presents a novel structure of parallel manipulators from Delta robot family for chest compressions in rescuing a patient. Also, two new control methodologies are applied to track the desired trajectory. Based on one supervisory approach and another one based upon adaptive neuro-fuzzy inference system (ANFIS) approach. Inverse dynamic modeling is performed based on principle of virtual work and the results are verified using MSC.Adams© software. The proportional derivative (PD) controllers of computed torque (C-T) method usually need manual retuning to make a successful task, particularly in the presence of disturbance. In the present paper, we study and compare the feasibility of applying supervisory controller and ANFIS instead of conventional controller used in C-T method to cope with the above mentioned problem. Several computer simulations imply that the proposed method is encouraging compared with C-T method implemented with conventional controller.

Fault tolerance of parallel manipulators using task space and kinematic redundancy

2006 ◽  
Vol 22 (5) ◽  
pp. 1017-1021 ◽  
Author(s):  
Yong Yi ◽  
J.E. McInroy ◽  
Yixin Chen
Keyword(s):  
Fault Tolerance ◽  
Parallel Manipulators ◽  
Task Space ◽  
Kinematic Redundancy

Model-based evaluation of mechanisms and benefits of mainstream shortcut nitrogen removal processes

2015 ◽  
Vol 71 (6) ◽  
pp. 840-847 ◽  
Author(s):  
Ahmed Al-Omari ◽  
Bernhard Wett ◽  
Ingmar Nopens ◽  
Haydee De Clippeleir ◽  
Mofei Han ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Control Strategies ◽  
Model Based ◽  
Main Challenge ◽  
Nitrite Oxidizing Bacteria ◽  
Shortcut Nitrogen Removal ◽  
Target Ratio ◽  
Removal Processes ◽  
Selection Mechanisms ◽  
The Impact

The main challenge in implementing shortcut nitrogen removal processes for mainstream wastewater treatment is the out-selection of nitrite oxidizing bacteria (NOB) to limit nitrate production. A model-based approach was utilized to simulate the impact of individual features of process control strategies to achieve NO−2-N shunt via NOB out-selection. Simulations were conducted using a two-step nitrogen removal model from the literature. Nitrogen shortcut removal processes from two case studies were modeled to illustrate the contribution of NOB out-selection mechanisms. The paper highlights a comparison between two control schemes; one was based on online measured ammonia and the other was based on a target ratio of 1 for ammonia vs. NOx (nitrate + nitrite) (AVN). Results indicated that the AVN controller possesses unique features to nitrify only that amount of nitrogen that can be denitrified, which promotes better management of incoming organics and bicarbonate for a more efficient NOB out-selection. Finally, the model was used in a scenario analysis, simulating hypothetical optimized performance of the pilot process. An estimated potential saving of 60% in carbon addition for nitrogen removal by implementing full-scale mainstream deammonification was predicted.

Trajectory Planning and Impact Reduction in Wire-Actuated Parallel Manipulators With Elastic Wires

2010 ◽  
Author(s):  
Maryam Agahi ◽  
Leila Notash
Keyword(s):  
Trajectory Planning ◽  
Parallel Manipulator ◽  
Optimal Trajectory ◽  
Parallel Manipulators ◽  
Mobile Platform ◽  
Kinematics And Dynamics ◽  
Redundancy Resolution ◽  
Impact Reduction ◽  
Optimization Routine ◽  
Optimal Trajectory Planning

In the work presented, the optimal trajectory planning in wire-actuated parallel manipulators in the presence of an obstacle is investigated. The kinematics and dynamics of a wire-actuated parallel manipulator considering the elasticity and damping effects of wires are described. The redundancy resolution of planar wire-actuated parallel manipulators is investigated at the torque level in order to perform desirable tasks to minimize the effect of impact, while maintaining positive tension in each wire. A local optimization routine is used in the simulation to minimize the tension in the wires while modifying the trajectory of the mobile platform and maintaining positive wire tensions. During collision, the tension in the wires is optimized to reduce the effect of impact, and after collision, the trajectory is modified and the wire tensions are minimized in order to avoid collision for the remainder of the trajectory. The effectiveness of the presented approach is studied through a simulation of an example planar wire-actuated manipulator.

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