Analysis of the Weighting Matrix for Load Distribution Using Weighted Pseudoinverse in a Redundantly Actuated System

Volume 2 ◽

10.1115/esda2004-58404 ◽

2004 ◽

Author(s):

Dong Il Park ◽

Soo Hyun Kim ◽

Yoon Keun Kwak

Keyword(s):

Load Distribution ◽

Redundant Actuation ◽

Maximum Torque ◽

Distribution Method ◽

Torque Distribution ◽

Weighting Matrix ◽

Weighted Pseudoinverse ◽

Actuation System ◽

Redundantly Actuated ◽

Stiffness Control

Redundant actuation indicates a situation when there are more actuators than a system’s mobility. A redundant actuated system has many strengths, such as better performance than a non-redundant system, avoiding singularity, reducing impact force using active stiffness control and fault tolerance. However, there are some issues on economic efficiency and minimization of a system, because redundant actuation can use more actuators than non-redundant actuation. Also, in a redundant actuation system, the actuator torque does not have one solution, but rather there are infinite torque sets even though a robot works on the same task. Therefore, it is very important to select a torque distribution method that is suitable for the objectives of the robot. In this paper, we used the weighted pseudoinverse matrix for torque distribution. This method is applied to a five bar link system and the influence of the weighting variables is analyzed. By adjusting the weighting values, we can find the relation between the actuator input and the weighting value and obtain various torque sets in real time. In other words, we find how each actuator torque changes according to the variation of each weighting value and how much the maximum torque reduce for the suggested weighting matrices.

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Optimal torque distribution method for a redundantly actuated 3-RRR parallel robot using a geometrical approach

Robotica ◽

10.1017/s0263574712000562 ◽

2012 ◽

Vol 31 (4) ◽

pp. 549-554 ◽

Cited By ~ 13

Author(s):

Ho-Seok Shim ◽

TaeWon Seo ◽

Jeh Won Lee

Keyword(s):

Stiffness Matrix ◽

Screw Theory ◽

Null Space ◽

Geometric Analysis ◽

Parallel Robot ◽

Geometrical Approach ◽

Space Vector ◽

Distribution Method ◽

Torque Distribution ◽

Redundantly Actuated

SUMMARYIn this paper, a novel optimal torque distribution method for a redundantly actuated parallel robot is proposed. Geometric analysis based on screw theory is performed to calculate the stiffness matrix of a redundantly actuated 3-RRR parallel robot. The analysis is performed based on statics focusing on low-speed motions. The stiffness matrix consisting of passive and active stiffness is also derived by the differentiation of Jacobian matrix. Comparing two matrices, we found that null-space vector is related to link geometry. The optimal distribution torque is determined by adapting mean value of minimum and maximum angles as direction angles of null-space vector. The resulting algorithm is validated by comparing the new method with the minimum-norm method and the weighted pseudo-inverse method for two different paths and force conditions. The proposed torque distribution algorithm shows the characteristics of minimizing the maximum torque.

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Torque distribution optimization of redundantly actuated planar parallel mechanisms based on a null-space solution

Robotica ◽

10.1017/s0263574713001288 ◽

2014 ◽

Vol 32 (7) ◽

pp. 1125-1134 ◽

Cited By ~ 6

Author(s):

Jung Hyun Choi ◽

TaeWon Seo ◽

Jeh Won Lee

Keyword(s):

Screw Theory ◽

Null Space ◽

Critical Role ◽

Main Idea ◽

Redundant Actuation ◽

Parallel Mechanisms ◽

Efficient Manner ◽

Distribution Method ◽

Torque Distribution ◽

Space Solution

SUMMARYRedundant actuation for the parallel kinematic machine (PKM) is a well-known technique for overcoming general drawbacks of the PKM by helping it to avoid singularity and enhance stiffness characteristics, among others. Torque distribution plays a critical role in redundant actuation because this actuation causes the PKM to consume too much energy or put a substantial amount of stress on joints and links. This paper proposes a new torque distribution method for reducing the maximum torque of the actuator of a planar PKM. Here the main idea behind the proposed method is the use of superposition of a particular solution for a non-redundant case and an optimized null-space solution for a redundant case with a constant coefficient. The optimal value of a null-space solution can be easily determined by checking only the intersection points of the profile of the actuator's torque as the coefficient varies. We consider three cases of planar PKMs—2-, 3-, and 4-RRR PKMs—and present a detailed procedure for deriving a kinematic solution for the 2-RRR PKM based on Screw theory. We compare the proposed method with the minimum-norm pseudo-inverse method and assess a limitation of the proposed method. The torque distribution algorithm can be used to determine the number of actuators in an efficient manner and to reduce energy consumption.

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Torque distribution using a weighted pseudoinverse in a redundantly actuated mechanism

Advanced Robotics ◽

10.1163/156855303322395226 ◽

2003 ◽

Vol 17 (8) ◽

pp. 807-820 ◽

Cited By ~ 13

Author(s):

Dong Il Park ◽

Sang Heon Lee ◽

Soo Hyun Kim ◽

Yoon Keun Kwak

Keyword(s):

Torque Distribution ◽

Weighted Pseudoinverse ◽

Redundantly Actuated

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Active fault tolerant control scheme for aircraft with dissimilar redundant actuation system subject to hydraulic failure

Journal of the Franklin Institute ◽

10.1016/j.jfranklin.2018.11.018 ◽

2019 ◽

Vol 356 (3) ◽

pp. 1302-1332 ◽

Cited By ~ 6

Author(s):

Salman Ijaz ◽

Lin Yan ◽

Mirza Tariq Hamayun ◽

Cun Shi

Keyword(s):

Active Fault ◽

Fault Tolerant ◽

Fault Tolerant Control ◽

Redundant Actuation ◽

Hydraulic Failure ◽

Actuation System ◽

Control Scheme ◽

Active Fault Tolerant Control

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Development of the Control Strategy for an Innovative 4WD Device

Volume 2: Automotive Systems, Bioengineering and Biomedical Technology, Fluids Engineering, Maintenance Engineering and Non-Destructive Evaluation, and Nanotechnology ◽

10.1115/esda2006-95399 ◽

2006 ◽

Cited By ~ 1

Author(s):

Federico Cheli ◽

Paolo Dellacha` ◽

Andrea Zorzutti

Keyword(s):

Automotive Industry ◽

Controller Design ◽

Rear Wheel ◽

Front Axle ◽

Torque Distribution ◽

Actuation System ◽

Wheel Drive ◽

Wet Clutch ◽

The One ◽

Engine Crankshaft

The potentialities shown by controlled differentials are making the automotive industry to explore this field. While VDC systems can only guarantee a safe behaviour at limit, a controlled differential can also increase the handling performance. The system derives from a rear wheel drive architecture with a semi-active differential, to which has been added a controlled wet clutch that directly connects the front axle and the engine crankshaft. This device allows distributing the drive torque between the two axles, according to the constraints due to kinematics and thermal problems. It can be easily understood that in this device the torque distribution doesn’t depend only from the central clutch action, but also from the engaged gear. Because of that the central clutch controller has to consider the gear position too. The control algorithms development was carried on using a vehicle model which can precisely simulate the handling response, the powertrain dynamic and the actuation system behaviour. A right powertrain response required the development of a customize library in Simulink. The approach chosen to carry on this research was the one used in automotive industry nowadays: an intensive simulation campaign was executed to realize an initial controller design and tuning.

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Active fault-tolerant control for vertical tail damaged aircraft with dissimilar redundant actuation system using integral sliding mode control

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406218790280 ◽

2018 ◽

Vol 233 (7) ◽

pp. 2361-2378 ◽

Cited By ~ 1

Author(s):

Salman Ijaz ◽

Mirza T Hamayun ◽

Lin Yan ◽

Cun Shi

Keyword(s):

Actuator Saturation ◽

Fault Tolerant ◽

Sliding Mode ◽

Fault Tolerant Control ◽

Fault Estimation ◽

Redundant Actuation ◽

Severe Damage ◽

Integral Sliding Mode ◽

Actuation System ◽

Electrohydraulic Actuator

The research about the dissimilar redundant actuation system has indicated the potential fault-tolerant capability in modern aircraft. This paper proposed a new design methodology to achieve fault-tolerant control of an aircraft equipped with dissimilar actuators and is suffered from vertical tail damage. The proposed design is based on the concept of online control allocation to redistribute the control signals among healthy actuators and integral sliding mode controller is designed to achieve the closed-loop stability in the presence of both component and actuator faults. To cope with severe damage condition, the aircraft is equipped with dissimilar actuators (hydraulic and electrohydraulic actuators). In this paper, the performance degradation due to slower dynamics of electrohydraulic actuator is taken in account. Therefore, the feed-forward compensator is designed for electrohydraulic actuator based on fractional-order control strategy. In case of failure of hydraulic actuator subject to severe damage of vertical tail, an active switching mechanism is developed based on the information of fault estimation unit. Additionally, a severe type of actuator failure so-called actuator saturation or actuator lock in place is also taken into account in this work. The proposed strategy is compared with the existing control strategies in the literature. Simulation results indicate the dominant performance of the proposed scheme. Moreover, the proposed controller is found robust with a certain level of mismatch between the actuator effectiveness level and its estimate.

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