scholarly journals Adaptive Variable Parameter Impedance Control for Apple Harvesting Robot Compliant Picking

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Ji Wei ◽  
Ding Yi ◽  
Xu Bo ◽  
Chen Guangyu ◽  
Zhao Dean
Keyword(s):  
Control System ◽  
Contact Force ◽  
Control Method ◽  
Impedance Control ◽  
Viscoelastic Model ◽  
Variable Parameter ◽  
Response Speed ◽  
Self Tuning ◽  
Impedance Parameters ◽  
Harvesting Robot

In order to reduce the damage of apple harvesting robot to fruits and achieve compliant picking, an adaptive variable parameter impedance control method for apple harvesting robot compliant picking is proposed in this paper. Firstly, the Burgers viscoelastic model is used to characterize the rheological properties of apples and study the variation of mechanical properties of apple grasping at different speeds. Then, a force-based impedance control system is designed. On this basis, aiming at the influence of impedance controller parameters on contact force, three impedance parameters self-tuning functions are constructed to complete the design of an improved force-based impedance control system based on the hyperbolic secant function. The simulation and experimental results show that the proposed control makes the desired force smoother, and its overshoot is about 2.3%. The response speed is faster, and the adjustment time of contact force is shorter of about 0.48 s. The contact force overshoot is about 2%, which is 37.5% less than that of the traditional force-based impedance control. This research improves the control performance for apple harvesting robot compliant picking.

Variable impedance control of finger exoskeleton for hand rehabilitation following stroke

2019 ◽  
Vol 47 (1) ◽  
pp. 23-32
Author(s):  
Fuhai Zhang ◽  
Legeng Lin ◽  
Lei Yang ◽  
Yili Fu
Keyword(s):  
Control System ◽  
Real Time ◽  
Control Method ◽  
Impedance Control ◽  
Contact Forces ◽  
Hand Rehabilitation ◽  
Content Type ◽  
Flexion Extension ◽  
Output Trajectory ◽  
Impedance Parameters

Purpose The purpose of this paper is to propose a variable impedance control method of finger exoskeleton for hand rehabilitation using the contact forces between the finger and the exoskeleton, making the output trajectory of finger exoskeleton comply with the natural flexion-extension (NFE) trajectory accurately and adaptively. Design/methodology/approach This paper presents a variable impedance control method based on fuzzy neural network (FNN). The impedance control system sets the contact forces and joint angles collected by sensors as input. Then it uses the offline-trained FNN system to acquire the impedance parameters in real time, thus realizing tracking the NFE trajectory. K-means clustering method is applied to construct FNN, which can obtain the number of fuzzy rules automatically. Findings The results of simulations and experiments both show that the finger exoskeleton has an accurate output trajectory and an adaptive performance on three subjects with different physiological parameters. The variable impedance control system can drive the finger exoskeleton to comply with the NFE trajectory accurately and adaptively using the continuously changing contact forces. Originality/value The finger is regarded as a part of the control system to get the contact forces between finger and exoskeleton, and the impedance parameters can be updated in real time to make the output trajectory comply with the NFE trajectory accurately and adaptively during the rehabilitation.

scholarly journals Research and Ground Verification of the Force Compliance Control Method for Space Station Manipulator

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Bingshan Hu ◽  
Huanlong Chen ◽  
Liangliang Han ◽  
Hongliu Yu
Keyword(s):  
Real Time ◽  
Contact Force ◽  
Control Algorithm ◽  
Control Method ◽  
Impedance Control ◽  
Space Station ◽  
Gravity Compensation ◽  
Compliance Control ◽  
Experiment Platform ◽  
Dual Arm

The space station manipulator does lots of tasks with contact force/torque on orbit. To ensure the safety of the space station and the manipulator, the contact force/torque of manipulator must be controlled. Based on analyzing typical tasks’ working flows and force control requirements, such as ORU (orbit replacement unit) changeout and dual arm collaborative payload transport, an impedance control method based on wrist 6 axis force/torque feedback is designed. For engineering implementation of the impedance control algorithm, the discretization method and impedance control parameters selection principle are also studied. To verify the compliance control algorithm, a ground experiment platform adopting industrial manipulators is developed. In order to eliminate the influence of gravity, a real-time gravity compensation algorithm is proposed. Then, the correctness of real-time gravity compensation and force compliance control algorithm is verified on the experiment platform. Finally, the ORU replacement and dual arm collaborative payload transport experiments are done. Experimental results show that the force compliance control method proposed in this paper can control the contact force and torque at the end of the manipulator when executing typical tasks.

Adaptive stable grasping control strategy based on slippage detection

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yang Chen ◽  
Fuchun Sun
Keyword(s):  
Control System ◽  
Contact Force ◽  
Control Strategy ◽  
Control Method ◽  
Engineering Application ◽  
Stable State ◽  
Content Type ◽  
Circuit Components ◽  
Unknown Disturbance ◽  
Slippage Detection

Purpose The authors want to design an adaptive grasping control strategy without setting the expected contact force in advance to maintain grasping stable, so that the proposed control system can deal with unknown object grasping manipulation tasks. Design/methodology/approach The adaptive grasping control strategy is proposed based on bang-bang-like control principle and slippage detection module. The bang-bang-like control method is designed to find and set the expected contact force for the whole control system, and the slippage detection function is achieved by dynamic time warping algorithm. Findings The expected contact force can adaptively adjust in grasping tasks to avoid bad effects on the control system by the differences of prior test results or designers. Slippage detection can be recognized in time with variation of expected contact force manipulation environment in the control system. Based on if the slippage caused by an unexpected disturbance happens, the control system can automatically adjust the expected contact force back to the level of the previous stable state after a given time, and has the ability to identify an unnecessary increasing in the expected contact force. Originality/value Only contact force is used as feedback variable in control system, and the proposed strategy can save hardware components and electronic circuit components for sensing, reducing the cost and design difficulty of conducting real control system and making it easy to realize in engineering application field. The expected contact force can adaptively adjust due to unknown disturbance and slippage for various grasping manipulation tasks.

scholarly journals The Neural Network-Combined Optimal Control System of Induction Motor

2019 ◽  
Vol 9 (4) ◽  
pp. 2513
Author(s):  
Thang Nguyen Trong
Keyword(s):  
Neural Network ◽  
Optimal Control ◽  
Control System ◽  
Induction Motor ◽  
Control Method ◽  
Response Speed ◽  
The State ◽  
Linear Quadratic ◽  
Neuron Network ◽  
The Neural Network

<span lang="EN-US">This research aims to propose the optimal control method combined with the neuron network for an induction motor. In the proposed system, the induction motor is a nonlinear object which is controlled at each working point. At these working-points, the state equation of the induction motor is linear, so it is possible to apply the linear quadratic regular algorithm for the induction motor. Therefore, the parameters of the state feedback controller are the functions. The output-input relationships of these functions are set through the neural network. The numerical simulation results show that the quality of the control system of the induction motor is very high: The response speed always follows the desired speed with the short transition time and the small overshoot. Furthermore, the system is robust in the case of changing the load torque, and the parameters of the induction motor are incorrectly defined</span>

Development of User-friendly Tuning for Impedance Control Parameters

2001 ◽  
Vol 13 (3) ◽  
pp. 230-237
Author(s):  
Junji shimamura ◽  
◽  
Masaki Arao ◽  
Keyword(s):  
Control System ◽  
Force Control ◽  
Impedance Control ◽  
External Environment ◽  
Parameter Tuning ◽  
Control Parameters ◽  
Trial And Error ◽  
Impedance Parameters ◽  
User Friendly ◽  
Ic Test

Impedance control, a type of indirect force control, is a method for providing a control system with compliance against forces effected by external environment. This method is expected to be applied primarily to industrial purposes, but it has such disadvantages that the process for tuning its parameters is based on a trial-and-error rule and largely depends on the controlling skill of operators. This paper describes a parameter tuning tool capable of readily setting the optimum impedance parameters and then clarifies the effectiveness of the suggested tool according to the results of experiments conducted on IC test inserter. Operators are not necessarily required to acquire the knowledge about impedance control.

Research on the Space Manipulator Control in Capturing Object Based on Noncontact Impedance Control

2012 ◽  
Vol 546-547 ◽  
pp. 1014-1019 ◽  
Author(s):  
Zhi Gang Chen ◽  
Cui Ru Wu ◽  
Guang Yu Zhang
Keyword(s):  
Control Method ◽  
Impedance Control ◽  
Joint Space ◽  
Space Manipulator ◽  
Object Based ◽  
Space Manipulators ◽  
Impedance Parameters ◽  
The Impact ◽  
Virtual Impedance ◽  
Manipulator Control

This paper discusses the control of free flying space manipulators in the impact process which happens in the capturing operation. To solve the intense coupling of the kinematics and dynamics between the space manipulator and the base, this paper builds the noncontact impedance control model of the 6-joint space manipulator system, which can control the space manipulator before impacting with the objects. Computer simulations are performed to verify that the noncontact impedance control method can make the end-effector of the space manipulator keep desired dynamic characteristics and the adjustment of virtual impedance parameters can control the impact force value efficiently.

Induction Motor Direct Torque Control Method of Fuzzy Adaptive

2013 ◽  
Vol 387 ◽  
pp. 365-368
Author(s):  
Cong Fan ◽  
Guo Zhang ◽  
Yu Ping Liu
Keyword(s):  
Control System ◽  
Control Method ◽  
Asynchronous Motor ◽  
Direct Torque Control ◽  
Adaptive Method ◽  
Torque Control ◽  
The Self ◽  
Self Tuning ◽  
Simulation Results ◽  
Fuzzy Adaptive

This paper focus on the instability of asynchronous motor direct torque control system which caused by PID parameter changes. In order to improve the self-tuning capabilitiy of PID countroller, enhance the speed and stability of control system. fuzzy adaptive method was adapted to optimize PID parameter. Simulation results show that: this strategy improved the performance of direct torque control system significantly.

Hybrid Impedance Control of Massage Considering Dynamic Interaction of Human and Robot Collaboration Systems

2009 ◽  
Vol 21 (1) ◽  
pp. 146-155 ◽  
Author(s):  
Kazuhiko Terashima ◽  
◽  
Takanori Miyoshi ◽  
Keisuke Mouri ◽  
Hideo Kitagawa ◽  
...  
Keyword(s):  
Control System ◽  
Human Skin ◽  
Control Method ◽  
Impedance Control ◽  
Vertical Direction ◽  
Lateral Position ◽  
Robot Hand ◽  
Control Methods ◽  
Massage Therapist ◽  
Robot Perception

This paper proposes an intelligent massage control system that uses a multi-fingered robot hand with hybrid impedance control, which is able to recreate the movement and force of a human massage therapist. Therefore, various massage points, such as changes in the stiffness of human skin muscle, can be controlled by using an impedance control method. A hybrid impedance control, comprised of position-based and force-based control methods, was developed. The position-based impedance control is used to control the lateral position of massage on the human skin muscle. On the other hand, the force-based impedance control is used to control the force of the vertical direction on human skin muscle. This paper also identifies human skin muscle through robot perception of impedance to decide on the parameters of the impedance controller. A strategy using impedance control to implement an adaptive control system is presented, under the conditions of both soft and hard skin and muscle. The effectiveness of this massage control system using a multi-fingered robot hand with hybrid impedance control is demonstrated through realistic massage experiments involving pushing and rubbing motions.

Impedance Control of a Pneumatic Servo System with Adaptive Control Method

1991 ◽  
Vol 3 (6) ◽  
pp. 463-469 ◽  
Author(s):  
Toshiro Noritsugu ◽  
◽  
Tsutomu Wada ◽  
Toshiaki Asanoma ◽  
◽  
...  
Keyword(s):  
Adaptive Control ◽  
Control System ◽  
Position Control ◽  
Control Method ◽  
Reference Model ◽  
Impedance Control ◽  
Servo System ◽  
Operating Conditions ◽  
Pneumatic Cylinder ◽  
Pneumatic Servo System

One of the typical features of a pneumatic servo is a relatively high compliance due to air compressibility. This feature may be useful for constrained tasks such as deburring, polishing, and assisting humans, in which the relationship between position and force is important. If this relationship of a pneumatic servo becomes actively controllable, it can be effectively applied to these tasks. In order to control this relationship, an impedance control concept has recently been proposed. The impedance of the overall control system depends not only on the manipulator but also on the manipulated object of which the characteristics are usually unknown. Therefore, to attain the desired impedance over extensive operating conditions, an adaptive control strategy is required. This paper proposes an impedance control method of a pneumatic servo, using a position based approach, where an adaptive position control system is constructed inside the force feedback loop. The proposed method is applied to an experimental pneumatic servo system comprised of a pneumatic cylinder, electro-pneumatic proportional control valves, and a spring object. From the experiments, the following has been verified: 1) both static stiffness and dynamic impedance of the pneumatic servo system can be independently regulated by setting a desired reference model; 2) the impedance can be held constant with changes in system parameter such as object stiffness; and 3) the instability problem for the low stiffness setting can be overcome by setting high damping in the reference model. The proposed impedance control method may prove to be effective for both improving a pneumatic servo and developing its new applications.

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