scholarly journals Optimal Force Allocation and Position Control of Hybrid Pneumatic–Electric Linear Actuators

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 86
Author(s):  
Behrad Rouzbeh ◽  
Gary M. Bone
Keyword(s):  
Position Control ◽  
Controller Design ◽  
Mechanical Impedance ◽  
Service Robots ◽  
Position Tracking ◽  
Computationally Efficient ◽  
Pneumatic Actuators ◽  
Large Bandwidth ◽  
Time Operation ◽  
Redundant Actuators

Hybrid pneumatic–electric actuators (HPEAs) are redundant actuators that combine the large force, low bandwidth characteristics of pneumatic actuators with the large bandwidth, small force characteristics of electric actuators. It has been shown that HPEAs can provide both accurate position control and high inherent safety, due to their low mechanical impedance, making them a suitable choice for driving the joints of assistive, collaborative, and service robots. If these characteristics are mathematically modeled, input allocation techniques can improve the HPEA’s performance by distributing the required input (force or torque) between the redundant actuators in accordance with each actuator’s advantages and limitations. In this paper, after developing a model for a HPEA-driven system, three novel model-predictive control (MPC) approaches are designed that solve the position tracking and input allocation problem using convex optimization. MPC is utilized since the input allocation can be embedded within the motion controller design as a single optimization problem. A fourth approach based on conventional linear controllers is included as a comparison benchmark. The first MPC approach uses a model that includes the dynamics of the payload and pneumatics; and performs the motion control using a single loop. The latter methods simplify the MPC law by separating the position and pressure controllers. Although the linear controller was the most computationally efficient, it was inferior to the MPC-based controllers in position tracking and force allocation performance. The third MPC-based controller design demonstrated the best position tracking with RMSE of 46%, 20%, and 55% smaller than the other three approaches. It also demonstrated sufficient speed for real-time operation.

Impedance Reduction Controller Design for Mechanical Systems

2013 ◽  
Author(s):  
Hanseung Woo ◽  
Kyoungchul Kong
Keyword(s):  
Case Studies ◽  
Closed Loop ◽  
Controller Design ◽  
Mechanical Impedance ◽  
Open Loop ◽  
Mechatronic Systems ◽  
Closed Loop Systems ◽  
Guaranteed Stability ◽  
Reaction Forces ◽  
Definition Of

Safety is one of important factors in control of mechatronic systems interacting with humans. In order to evaluate the safety of such systems, mechanical impedance is often utilized as it indicates the magnitude of reaction forces when the systems are subjected to motions. Namely, the mechatronic systems should have low mechanical impedance for improved safety. In this paper, a methodology to design controllers for reduction of mechanical impedance is proposed. For the proposed controller design, the mathematical definition of the mechanical impedance for open-loop and closed-loop systems is introduced. Then the controllers are designed for stable and unstable systems such that they effectively lower the magnitude of mechanical impedance with guaranteed stability. The proposed method is verified through case studies including simulations.

scholarly journals Obstacle detection for autonomous systems using stereoscopic images and bacterial behaviour

2020 ◽  
Vol 10 (2) ◽  
pp. 2164
Author(s):  
Fredy Martinez ◽  
Edwar Jacinto ◽  
Fernando Martinez
Keyword(s):  
Real Time ◽  
High Performance ◽  
Time Estimation ◽  
Obstacle Detection ◽  
Stereoscopic Vision ◽  
Human Interaction ◽  
Human Model ◽  
Service Robots ◽  
Indoor Environments ◽  
Time Operation

This paper presents a low cost strategy for real-time estimation of the position of obstacles in an unknown environment for autonomous robots. The strategy was intended for use in autonomous service robots, which navigate in unknown and dynamic indoor environments. In addition to human interaction, these environments are characterized by a design created for the human being, which is why our developments seek morphological and functional similarity equivalent to the human model. We use a pair of cameras on our robot to achieve a stereoscopic vision of the environment, and we analyze this information to determine the distance to obstacles using an algorithm that mimics bacterial behavior. The algorithm was evaluated on our robotic platform demonstrating high performance in the location of obstacles and real-time operation.

Accurate Position Control of a Pneumatic Actuator

1990 ◽  
Vol 112 (4) ◽  
pp. 734-739 ◽  
Author(s):  
Jiing-Yih Lai ◽  
Chia-Hsiang Menq ◽  
Rajendra Singh
Keyword(s):  
Control Strategy ◽  
Pulse Width Modulation ◽  
Position Control ◽  
Integral Control ◽  
Pneumatic Actuators ◽  
Actuator Dynamics ◽  
Position Accuracy ◽  
Modulation Mode ◽  
Nonlinear Mechanical ◽  
Accurate Position

We propose a new control strategy for on-off valve controlled pneumatic actuators and robots with focus on the position accuracy. A mathematical model incorporating pneumatic process nonlinearities and nonlinear mechanical friction has been developed to characterize the actuator dynamics; this model with a few simplifications is then used to design the controller. In our control scheme, one valve is held open and the other is operated under the pulse width modulation mode to simulate the proportional control. An inner loop utilizing proportional-plus-integral control is formed to control the actuator pressure, and an outer loop with displacement and velocity feedbacks is used to control the load displacement. Also, a two staged feedforward force is implemented to reduce the steady state error due to the nonlinear mechanical friction. Experimental results on a single-degree-of-freedom pneumatic robot indicate that the proposed control system is better than the conventional on-off control strategy as it is effective in achieving the desired position accuracy without using any mechanical stops in the actuator.

Automated System of Stabilization and Position Control of Aviation Equipment

2019 ◽  
pp. 297-330
Author(s):  
Olha Sushchenko
Keyword(s):  
Position Control ◽  
Transfer Functions ◽  
Controller Design ◽  
Robust Stabilization ◽  
Automated System ◽  
Simulink Model ◽  
The Matrix ◽  
Stabilized Platform ◽  
And Control ◽  
The Mathematical Model

In this chapter, the author presents the problems of design of the robust automated system for stabilization and control of platforms with aircraft observation equipment. The mathematical model of the triaxial stabilized platform is developed. The procedure of synthesis of robust stabilization system based on robust structural synthesis is represented. The above-mentioned procedure uses loop-shaping approach and method of the mixed sensitivity. The matrix weighting transfer functions are obtained. The optimization programs in MatLab are developed. The developed procedures are approved based on the results of simulation by means of the appropriate Simulink model. The obtained results can be useful for unmanned aerial vehicles and aircraft of special aviation, which are used for monitoring technical objects and aerial photography. The technical contributions are procedures of the robust controller design represented as the flowchart. The proposed approach is validated by application of the theoretical suppositions to the concrete example and appropriate simulation results.

Development of Low-Cost Wearable Servo Valve Using Buckled Tube Driven by Servo Motor

2013 ◽  
Vol 393 ◽  
pp. 532-537 ◽  
Author(s):  
Abdul Nasir ◽  
Tetsuya Akagi ◽  
Shujiro Dohta ◽  
Ayumu Ono ◽  
Yusuke Masago
Keyword(s):  
Control System ◽  
Flow Rate ◽  
Position Control ◽  
Low Cost ◽  
Control Valve ◽  
Artificial Muscle ◽  
Pneumatic Actuators ◽  
Servo Valve ◽  
Precise Control ◽  
Care Systems

Recently, power assisted nursing care systems have received much attention and those researches have been done actively. In such a control system, an actuator and a control valve are mounted on the human body. Designing the system, the size and weight of the valve become serious concerns. The purpose of our study is to develop a small-sized, lightweight and low-cost servo valve for precise control using wearable pneumatic actuators. In this study, a low-cost wearable servo valve that can control the output flow rate by changing the twisted angle of the buckled tube in the servo valve is proposed and tested. The position control system of McKibben rubber artificial muscle using tested valve and embedded controller is also proposed and tested. As a result, we confirmed that the tested servo valve can control the flow rate in both supply and exhaust in an analog way. In addition, the estimated cost of the proposed valve can be reduced about 100 times cheaper (10 US Dollar) compared with the typical servo valve.

The Leveling Position Control of a Four-Axial Active Pneumatic Isolation System Using PWM-Driving Parallel Dual-On/Off Valves

2011 ◽  
Vol 110-116 ◽  
pp. 3176-3183 ◽  
Author(s):  
Mao Hsiung Chiang ◽  
Hao Ting Lin
Keyword(s):  
Trajectory Tracking ◽  
Vibration Isolation ◽  
Position Control ◽  
Controller Design ◽  
Sliding Mode ◽  
Tracking Performance ◽  
Trajectory Tracking Control ◽  
Isolation System ◽  
Adaptive Sliding Mode Controller ◽  
Novel Concept

This study aims to develop a leveling position control of an active PWM-controlled pneumatic isolation table system. A novel concept using parallel dual-on/off valves with PWM control signals is implemented to realize active control and to improve the conventional pneumatic isolation table that supported by four pneumatic cushion isolators. In this study, the cushion isolators are not only passive vibration isolation devices, but also pneumatic actuators in active position control. Four independent closed-loop position feedback control system are designed and implemented for the four axial isolators. In this study, on/off valves are used, and PWM is realized by software. Therefore, additional hardware circuit is not required to implement PWM and not only cost down but also reach control precision of demand. In the controller design, the Fourier series-based adaptive sliding-mode controller with H∞ tracking performance is used to deal with the uncertainty and time-varying problems of pneumatic system. Finally, the experiments on the pneumatic isolation table system for synchronous position and trajectory tracking control, including no-load and loading conditions, and synchronous position control with master-slave method, are implemented in order to verify that the controller for each cushion isolator can realize good position and trajectory tracking performance.

scholarly journals Experimental Studies on a New Controller Design and Implementation in Direct Methanol Fuel Cell

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 796
Author(s):  
Ramasamy Govindarasu ◽  
Solaiappan Somasundaram
Keyword(s):  
Fuel Cell ◽  
Real Time ◽  
Direct Methanol Fuel Cell ◽  
Controller Design ◽  
Experimental Studies ◽  
Set Point ◽  
Point Tracking ◽  
Time Operation ◽  
Direct Methanol ◽  
Methanol Fuel Cell

A dynamic model of a Direct Methanol Fuel Cell is developed in the MATLAB platform. A newly proposed Coefficient Diagram based Proportional Integral Controller (CD-PIC) is designed and its parameters are calculated. The newly designed CD-PIC is implemented in a real time Direct Methanol Fuel Cell (DMFC) experimental setup. Performances in real time operation of the Direct Methanol Fuel Cell (DMFC) are evaluated. The performance of CD-PIC is obtained under tracking of set point changes. In order to evaluate the CD-PIC performances, most popular tuning rules based Conventional PI Controllers (C-PIC) are also designed and analyzed. Set point tracking is carried out for the step changes of ±10% and ±15% at two different operational points. The controller performances are analyzed in terms of Controller Performance Measuring (CPM) indices. The said performance measures indicate that the proposed CD-PIC gives the superior performances for set point changes and found very much robust in controlling DMFC.

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