Passive Control of a Hydraulic Human Power Amplifier Using a Hydraulic Transformer

2015 ◽  
Author(s):  
Sangyoon Lee ◽  
Perry Y. Li
Keyword(s):  
Power Amplifier ◽  
Passive Control ◽  
Control Function ◽  
Hydraulic Actuator ◽  
Control Approach ◽  
Human Power ◽  
Hydraulic Transformer ◽  
Control Objective ◽  
Pressure Dynamics ◽  
Mechanical Tool

The hydraulic human power amplifier is a tool that uses hydraulic actuation to amplify the force that the human exerts on it. Our control objective and framework are to make the system behave like a passive mechanical tool when interacting with the human and with the work environment with a specified power scaling factor. A virtual velocity coordination control approach casts the human power amplifier problem into one of velocity coordination by generating a fictitious reference mechanical system. Force amplification becomes a natural consequence of velocity coordination. This control has been previously demonstrated using servo valves which is a major contributor to energy loss in hydraulic system. In this paper, a hydraulic transformer, which does not rely on throttling to accomplish its control function is used instead of a servo valve to achieve human power amplification. In addition, a passivity based control approach that makes use of the natural energy storage of the hydraulic actuator is used to define the flow requirement. This approach fully accounts for the non-linearity due to the pressure dynamics. The controller was experimentally validated with good force amplification and velocity coordination performance on a single degree of freedom hydraulic human power amplifier.

Multi Degree-of-Freedom Hydraulic Human Power Amplifier With Rendering of Assistive Dynamics

2016 ◽  
Author(s):  
Sangyoon Lee ◽  
Fredrik Eskilsson ◽  
Perry Y. Li
Keyword(s):  
Power Amplifier ◽  
Degree Of Freedom ◽  
Hydraulic Actuator ◽  
Full Account ◽  
Control Approach ◽  
Human Power ◽  
Natural Energy ◽  
Control Objective ◽  
Pressure Dynamics ◽  
Mechanical Tool

The hydraulic human power amplifier (HPA) is a tool similar to exoskeleton that uses hydraulic actuation to amplify the applied human force. The control objective is to make the system behave like a passive mechanical tool that interacts with the human and the environment passively with a specified power scaling factor. In our previous work, a virtual velocity coordination approach recasts the single degree-of-freedom human power amplifier control problem into a velocity coordination with a fictitious reference mechanical system. Force amplification becomes a natural consequence of the velocity coordination. In this paper, this control approach is extended for fully coupled multi-DoF systems. A passivity based control approach that uses the natural energy storage of the hydraulic actuator to take full account of the nonlinear pressure dynamics is used to define the flow requirement. Additional passive assistance dynamics are designed and implemented to enable the user to perform specific tasks more easily. Guidance is achieved using a passive velocity field controller (PVFC), and obstacle avoidance is achieved using a potential field. Experimental results demonstrate good performance on a 2-DoF Human Power Amplifier.

A New Passive Controller for a Hydraulic Human Power Amplifier

2006 ◽  
Author(s):  
Perry Y. Li
Keyword(s):  
Work Environment ◽  
Mechanical System ◽  
Power Amplifier ◽  
Scaling Factor ◽  
Natural Consequence ◽  
Constrained Motion ◽  
Proportional Integral ◽  
Human Power ◽  
Control Objective ◽  
Mechanical Tool

A new, intrinsically passive controller for hydraulic human power amplifier is presented. The hydraulic human power amplifier is a tool that amplifies (or attenuates) the force that the human exerts on it. The control objective is to cause the system to behave like a passive mechanical tool when interacting with the human and with the work environment with a specified power scaling factor. Although a previous Proportional-integral with velocity feedforward force controller [1] works well in the constrained space, it lacks robustness or performance during freemotion because of the sensitivity to the implementation of velocity feedforward term. The difficulty in implementing the velocity feedforward term also prevents the controller from being intrinsically passive. The new controller recasts the human power amplifier problem into one of velocity coordination by generating a fictitious reference mechanical system. Force amplification become a natural consequence of velocity coordination. This enables the controller to be intrinsically passive and to achieve good performance both in free motion and constrained motion. These properties have been experimentally validated.

Design and Control of a Hydraulic Human Power Amplifier

2004 ◽  
Author(s):  
Perry Y. Li
Keyword(s):  
Power Amplifier ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Parametric Uncertainties ◽  
Hydraulic Actuator ◽  
Closed Loop System ◽  
Static Loads ◽  
Human Power ◽  
Compression Spring ◽  
And Control

This paper describes the design of and some preliminary control results for a hydraulically actuated human power amplifier. The system is in the form of an oar, with its reach and pitch degrees of freedom being hydraulically assisted. A robust PI force controller is proposed so that the hydraulic actuator force tracks a scaled copy of the force exerted by the human. Nonlinearities and uncertainties in the compression spring, as well as parametric uncertainties are taken into account. The passivity property of the closed loop system is also analyzed. The controller has been tested in simulations and experimentally. It is shown to be effective when pushing against an object, and in assisting in bearing static loads.

scholarly journals A Critical Review of Supersonic Flow Control for High-Speed Applications

2021 ◽  
Vol 11 (15) ◽  
pp. 6899
Author(s):  
Abdul Aabid ◽  
Sher Afghan Khan ◽  
Muneer Baig
Keyword(s):  
Supersonic Flow ◽  
Flow Control ◽  
Active Control ◽  
Critical Review ◽  
High Speed ◽  
Passive Control ◽  
Control Method ◽  
Sudden Expansion ◽  
Control Approach ◽  
Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

scholarly journals The Human Power Amplifier Technology at the University Of California, Berkeley

1996 ◽  
Vol 29 (1) ◽  
pp. 5715-5720
Author(s):  
H. Kazerooni ◽  
Tanya J. Snyder
Keyword(s):  
Power Amplifier ◽  
University Of California ◽  
Human Power ◽  
The University

Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part Two—Robust Control

2011 ◽  
Author(s):  
Sai-Kit Wu ◽  
Garrett Waycaster ◽  
Tad Driver ◽  
Xiangrong Shen
Keyword(s):  
Robust Control ◽  
Nonlinear Model ◽  
Sliding Mode ◽  
Artificial Muscle ◽  
Control Approach ◽  
Actuation System ◽  
Highly Nonlinear ◽  
Pressure Dynamics ◽  
System Part ◽  
And Control

A robust control approach is presented in this part of the paper, which provides an effective servo control for the novel PAM actuation system presented in Part I. Control of PAM actuation systems is generally considered as a challenging topic, due primarily to the highly nonlinear nature of such system. With the introduction of new design features (variable-radius pulley and spring-return mechanism), the new PAM actuation system involves additional nonlinearities (e.g. the nonlinear relationship between the joint angle and the actuator length), which further increasing the control difficulty. To address this issue, a nonlinear model based approach is developed. The foundation of this approach is a dynamic model of the new actuation system, which covers the major nonlinear processes in the system, including the load dynamics, force generation from internal pressure, pressure dynamics, and mass flow regulation with servo valve. Based on this nonlinear model, a sliding mode control approach is developed, which provides a robust control of the joint motion in the presence of model uncertainties and disturbances. This control was implemented on an experimental setup, and the effectiveness of the controller demonstrated by sinusoidal tracking at different frequencies.

Application of Nonlinear Vibration Absorbers to the Control of Piston Secondary Motion in Internal Combustion Engines

2015 ◽  
Author(s):  
Nader Dolatabadi ◽  
Stephanos Theodossiades ◽  
Steve J. Rothberg
Keyword(s):  
Internal Combustion Engines ◽  
Passive Control ◽  
Internal Combustion ◽  
Impact Behavior ◽  
Combustion Engines ◽  
Impulsive Behavior ◽  
Control Approach ◽  
Operation Conditions ◽  
Secondary Motion ◽  
Nonlinear Energy

The impulsive behavior of piston plays a key role in the Noise, Vibration and Harshness (NVH) of internal combustion engines. There have been several studies on the identification and quantification of piston impacting action under various operation conditions. In the current study, the dynamics of piston secondary motion are briefly explored, since this is fundamental to understanding the aggressive oscillations, energy loss and noise generation. Concepts of controlling piston secondary motion (and thus, impacts) are investigated and a new passive control approach is presented based on the nonlinear energy absorption of the highly transient oscillations. The effectiveness of this new method on the improvement of piston impact behavior is discussed, using a preliminary optimization exercise (with respect to engine excitation/speed, damping and stiffness of the nonlinear oscillator) that leads to the conceptual design of a nonlinear energy absorber.

scholarly journals Robust Control Design to the Furuta System under Time Delay Measurement Feedback and Exogenous-Based Perturbation

Mathematics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 2131
Author(s):  
Gisela Pujol-Vazquez ◽  
Saleh Mobayen ◽  
Leonardo Acho
Keyword(s):  
Time Delay ◽  
Output Feedback Control ◽  
Linear Matrix ◽  
Control Block ◽  
Control Approach ◽  
Delay Measurement ◽  
Control Objective ◽  
Measurement Feedback ◽  
Robust Control Design ◽  
Delay Dependent

When dealing with real control experimentation, the designer has to take into account several uncertainties, such as: time variation of the system parameters, exogenous perturbation and the presence of time delay in the feedback line. In the later case, this time delay behaviour may be random, or chaotic. Hence, the control block has to be robust. In this work, a robust delay-dependent controller based on H∞ theory is presented by employing the linear matrix inequalities techniques to design an efficient output feedback control. This approach is carefully tuned to face with random time-varying measurement feedback and applied to the Furuta pendulum subject to an exogenous ground perturbation. Therefore, a recent experimental platform is described. Here, the ground perturbation is realised using an Hexapod robotic system. According to experimental data, the proposed control approach is robust and the control objective is completely satisfied.

scholarly journals PASSIVE CONTROL OF FLUID POWERED HUMAN POWER AMPLIFIERS

2008 ◽  
Vol 2008 (7-1) ◽  
pp. 207-212 ◽  
Author(s):  
Perry Y. Li ◽  
Venkat Durbha
Keyword(s):  
Power Amplifiers ◽  
Passive Control ◽  
Human Power
Sign in / Sign up

Export Citation Format

Share Document