scholarly journals A Lower Extremity Exoskeleton: Human-Machine Coupled Modeling, Robust Control Design, Simulation, and Overload-Carrying Experiment

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Qing Guo ◽  
Songjing Li ◽  
Dan Jiang
Keyword(s):  
Lower Extremity ◽  
Control Algorithm ◽  
Control Method ◽  
Parametric Uncertainty ◽  
Hydraulic Pressure ◽  
Hydraulic Actuator ◽  
Coupled Modeling ◽  
Robust Controller ◽  
Switched Control ◽  
Robust Control Design

A robustH∞control method and switched control algorithm for hydraulic actuator presents in human-machine coordinated motion to solve the motion delay of lower extremity exoskeleton. After the characteristic parameters synthesis of human limb and exoskeleton linkage, the human-machine coupled motion model is constructed to estimate the appropriate hydraulic pressure, which is considered as a structural uncertainty in hydraulic model. Then the robust controller is designed to improve the robust stability and performance under the structural and parametric uncertainty disturbances. Simulation results show that, in walking mode, this robust controller can achieve a better dynamic response and aid-force efficiency than PID controller. Then, according to gait divisions of person’s limb motion, the switched control algorithm is designed to reduce the delay of exoskeleton tracking person. Finally, the experimental results show that the human-machine coordinated walk with bearing 60 kg load and squat action with no external load are realized effectively by this proposed method.

IJFP-2018-0015 - Robust Control Design for an Inlet Metering Velocity Control System of a Linear Hydraulic Actuator

2020 ◽  
pp. 59-80 ◽  
Author(s):  
Hasan H Ali ◽  
Roger Fales
Keyword(s):  
Control System ◽  
Frequency Domain ◽  
Damping Ratio ◽  
Check Valve ◽  
Parametric Uncertainty ◽  
Velocity Control ◽  
Hydraulic Actuator ◽  
Robust Performance ◽  
Integral Control ◽  
Robust Control Design

In this paper, we consider a hydraulic system in which the velocity is controlled using an inlet-metered pump. The flow of the inlet-metered pump is controlled using an inlet metering valve that is placed upstream from a fixed displacement check valve pump. Placing the valve upstream from the pump reduces the energy losses across the valve. The multiplicative uncertainty associated with uncertain parameters in an inlet metering velocity control system is studied. Six parameters are considered in the uncertainty analysis. Four of the parameters are related to the valve dynamics which are the natural frequency, the damping ratio, the static gain, and the time delay. The other two parameters are the discharge coefficient and the fluid bulk modulus. Performance requirements for the system are described in the frequency domain. Frequency domain analysis is used to determine if the closed-loop velocity control system has robust performance. The time response of the nominal system with PID and H∞ controllers were found to be similar. The H∞ controller was found to have the advantages of robust performance when considering the parametric uncertainty while not requiring integral control as in the PID control system. The PID system did not achieve robust performance.

The Berkeley Lower Extremity Exoskeleton

2005 ◽  
Vol 128 (1) ◽  
pp. 14-25 ◽  
Author(s):  
H. Kazerooni ◽  
R. Steger
Keyword(s):  
Lower Extremity ◽  
Control Algorithm ◽  
Local Area Network ◽  
Control Method ◽  
Local Area ◽  
Area Network ◽  
System Sensitivity ◽  
Trade Offs ◽  
Control Schemes ◽  
Definition Of

The first functional load-carrying and energetically autonomous exoskeleton was demonstrated at the University of California, Berkeley, walking at the average speed of 1.3m∕s(2.9mph) while carrying a 34kg(75lb) payload. Four fundamental technologies associated with the Berkeley lower extremity exoskeleton were tackled during the course of this project. These four core technologies include the design of the exoskeleton architecture, control schemes, a body local area network to host the control algorithm, and a series of on-board power units to power the actuators, sensors, and the computers. This paper gives an overview of one of the control schemes. The analysis here is an extension of the classical definition of the sensitivity function of a system: the ability of a system to reject disturbances or the measure of system robustness. The control algorithm developed here increases the closed-loop system sensitivity to its wearer’s forces and torques without any measurement from the wearer (such as force, position, or electromyogram signal). The control method has little robustness to parameter variations and therefore requires a relatively good dynamic model of the system. The trade-offs between having sensors to measure human variables and the lack of robustness to parameter variation are described.

Model-based robust control design and experimental validation of SCARA robot system with uncertainty

2022 ◽  
pp. 107754632110421
Author(s):  
ShengChao Zhen ◽  
MuCun Ma ◽  
XiaoLi Liu ◽  
Feng Chen ◽  
Han Zhao ◽  
...  
Keyword(s):  
Robust Control ◽  
Control Algorithm ◽  
Lyapunov Method ◽  
Control Method ◽  
External Disturbance ◽  
Scara Robot ◽  
Model Based ◽  
Robust Control Design ◽  
Robot Performance ◽  
The Stability

In this paper, we design a novel robust control method to reduce the trajectory tracking errors of the SCARA robot with uncertainties including parameters such as uncertainty of the mechanical system and external disturbance, which are time-varying and nonlinear. Then, we propose a deterministic form of the model-based robust control algorithm to deal with the uncertainties. The proposed control algorithm is composed of two parts according to the assumed upper limit of the system uncertainties: one is the traditional proportional-derivative control, and the other is the robust control based on the Lyapunov method, which has the characteristics of model-based and error-based. The stability of the proposed control algorithm is proved by the Lyapunov method theoretically, which shows the system can maintain uniformly bounded and uniformly ultimately bounded. The experimental platform includes the rapid controller prototyping cSPACE, which is designed to reduce programming time and to improve the efficiency of the practical operation. Moreover, we adopt different friction models to investigate the effect of friction on robot performance in robot joints. Finally, numerical simulation and experimental results indicate that the control algorithm proposed in this paper has desired control performance on the SCARA robot.

Auto-calibration Based Control and Its Application to a Kind of Electrohydraulic Poppet Valves

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Patrick Opdenbosch ◽  
Nader Sadegh ◽  
Wayne Book
Keyword(s):  
Control Algorithm ◽  
Control Method ◽  
Pressure Control ◽  
The State ◽  
Input State ◽  
Hydraulic Pressure ◽  
The Novel ◽  
Supply Pressure ◽  
State Trajectory ◽  
Transition Map

This paper describes a novel learning/adaptive state trajectory control method and its application to electronic hydraulic pressure control. The control algorithm presented herein learns the inverse input-state mapping of the plant at the same time this map is employed in the feedforward loop to force the state of the plant to asymptotically converge to a prescribed state trajectory. The algorithm accomplishes this task without requiring prior exact information about the state transition map of the plant. The novel controller is applied to an electrohydraulic poppet valve with the objective of tracking a desired supply pressure signal. In this application, the controller learns the inverse conductance characteristics of the valve. The supply pressure tracking performance subject to the proposed controller is validated through experimental data.

Hydraulic Pressure Control System Simulation and Performance Test of Lower Extremity Exoskeleton

2012 ◽  
Vol 472-475 ◽  
pp. 2548-2553 ◽  
Author(s):  
Xing Xing Li ◽  
Qing Guo ◽  
Lu Lu Zhang ◽  
Hong Zhou ◽  
Xiang Gang Zhang
Keyword(s):  
Control System ◽  
Lower Extremity ◽  
Performance Test ◽  
Position Control ◽  
Control Method ◽  
Pressure Control ◽  
Frequency Domain Method ◽  
Hydraulic Pressure ◽  
Pressure Control System ◽  
And Performance

On basis of the introduction for the composition of carried-load assistance system and the control mechanism of hydraulic pressure valve for lower extremity exoskeleton, the position control loop is built. The control system is designed by frequency domain method using the PID parameters combined with lead correction network. Simulation results show that the control method can servo the angle of knee joint as human’s natural walk as well as the harmonious of man-machine moment. According to performance test of hydraulic pressure control system, the flow and pressure in piston is analyzed considering different load, the pressure of oil box and movable mode. Test results show that hydraulic pressure valve control system can realize efficiently slow walk carried 30 kilogram load, up and down stairs.

Robust Control Method Based on Machine Learning for Boiler Combustion System

2014 ◽  
Vol 685 ◽  
pp. 368-372 ◽  
Author(s):  
Hao Zhang ◽  
Ya Jie Zhang ◽  
Yan Gu Zhang
Keyword(s):  
Robust Control ◽  
Intelligent Control ◽  
Pid Control ◽  
Control Algorithm ◽  
Control Method ◽  
Support Vector ◽  
Control Performance ◽  
Fuzzy Pid Control ◽  
On Line ◽  
Control Output

In this study, we presented a boiler combustion robust control method under load changes based on the least squares support vector machine, PID parameters are on-line adjusted and identified by LSSVM, optimum control output is obtained. The simulation result shows control performance of the intelligent control algorithm is superior to traditional control algorithm and fuzzy PID control algorithm, the study provides a new control method for strong non-linear boiler combustion control system.

A Robust Control Design Approach Combining Exact Linearization and High-Gain PI-Observer

2007 ◽  
Author(s):  
Yan Liu ◽  
Dirk So¨ffker
Keyword(s):  
Feedback Linearization ◽  
Control Method ◽  
High Gain ◽  
Observer Design ◽  
Input State ◽  
Exact Linearization ◽  
Practical Applications ◽  
Robust Control Design ◽  
Nonlinear Control Method ◽  
Feedback Linearization Approach

This paper introduces a robust nonlinear control method combining classical feedback linearization and a high-gain PI-Observer (Proportional-Integral Observer) approach that can be applied to control a nonlinear single-input system with uncertainties or unknown effects. It is known that the lack of robustness of the feedback linearization approach limits its practical applications. The presented approach improves the robustness properties and extends the application area of the feedback linearization control. The approach is developed analytically and fully illustrated. An example which uses input-state linearization and PI-Observer design is given to illustrate the idea and to demonstrate the advantages.

The Lower Extremity Exoskeleton Coordinated Control Method Based on Human Electromechanical Coupling

2012 ◽  
Vol 220-223 ◽  
pp. 1012-1017
Author(s):  
Qing Guo ◽  
Dan Jiang
Keyword(s):  
Lower Extremity ◽  
Electromechanical Coupling ◽  
Position Control ◽  
Control Method ◽  
Angular Displacement ◽  
Stability Margin ◽  
Hydraulic Cylinder ◽  
Load Force ◽  
Hydraulic Cylinders ◽  
Coupling Characteristics

This paper has introduced electromechanical coupling characteristics in the lower extremity exoskeleton systems, considered model ,according to legs supporting gait when people walking, established the load torque compensation model , and a mathematical model of knee position control system which is made of the servo valve, hydraulic cylinders and other hydraulic components, designed hydraulic cylinder position control loop in case of existing load force interference compensation, and used the method of combining the PID and lead correction network for frequency domain design ,ensured system to meet a certain stability margin. The simulation results show that this position control method can servo on the knee angular displacement of normal human walking, reached a certain exoskeleton boost effect, at the same time, met the needs of human-machine coordinated motion.

Urban Oversaturated Traffic Network Control Based on Preference Multi-Objective Compatible Optimization Control

2011 ◽  
Vol 317-319 ◽  
pp. 1373-1384 ◽  
Author(s):  
Juan Chen ◽  
Chang Liang Yuan
Keyword(s):  
Control Problem ◽  
Control Algorithm ◽  
Control Method ◽  
Network Control ◽  
Feasible Region ◽  
Traffic Network ◽  
Total Delay ◽  
Multi Objective ◽  
Optimization Control ◽  
Objective Control

To solve the traffic congestion control problem on oversaturated network, the total delay is classified into two parts: the feeding delay and the non-feeding delay, and the control problem is formulated as a conflicted multi-objective control problem. The simultaneous control of multiple objectives is different from single objective control in that there is no unique solution to multi-objective control problems(MOPs). Multi-objective control usually involves many conflicting and incompatible objectives, therefore, a set of optimal trade-off solutions known as the Pareto-optimal solutions is required. Based on this background, a modified compatible control algorithm(MOCC) hunting for suboptimal and feasible region as the control aim rather than precise optimal point is proposed in this paper to solve the conflicted oversaturated traffic network control problem. Since it is impossible to avoid the inaccurate system model and input disturbance, the controller of the proposed multi-objective compatible control strategy is designed based on feedback control structure. Besides, considering the difference between control problem and optimization problem, user's preference are incorporated into multi-objective compatible control algorithm to guide the search direction. The proposed preference based compatible optimization control algorithm(PMOCC) is used to solve the oversaturated traffic network control problem in a core area of eleven junctions under the simulation environment. It is proved that the proposed compatible optimization control algorithm can handle the oversaturated traffic network control problem effectively than the fixed time control method.

The Design and Simulation for Two-Link Manipulators PD Robust Controller under Uncertain Upper Bound Disturbance

2013 ◽  
Vol 694-697 ◽  
pp. 1652-1655
Author(s):  
Ji Yan Wang
Keyword(s):  
Dynamic Characteristics ◽  
Upper Bound ◽  
Control Method ◽  
Robot Manipulator ◽  
Industrial Robot ◽  
Pd Controller ◽  
Robust Controller ◽  
Convergence And Stability ◽  
Comparison And Analysis ◽  
Driving Torque

PD control method is widely utilized for the dynamic characteristics controlling in industrial robot manipulator area. The disturbance is usually uncertain in reality; the traditional PD controller is limited in that case. In this paper, a PD robust controller is introduced to optimize the convergence and stability of PD controller and avoid the extreme initial driving torque for two-link manipulator system. Using the co-simulation on Matlab/ Simulink and ADAMS, the paper designs a PD robust controller under uncertain upper bound disturbance and completes track control and driving torque simulation trial. The superiority of the two-link manipulators PD robust controller is verified through result comparison and analysis.

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