scholarly journals Design and Performance of Nonlinear Control for an Electro-Hydraulic Actuator Considering a Wearable Robot

Processes ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 389 ◽  
Author(s):  
Song ◽  
Lee ◽  
Park ◽  
Baek
Keyword(s):  
Sliding Mode ◽  
Load Capacity ◽  
High Energy ◽  
Adaptive Sliding Mode Control ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Wearable Robot ◽  
Wearable Robots ◽  
And Performance ◽  
High Load Capacity

In the development of a wearable robot, compact volume size, high energy efficiency, and a high load capacity linear actuator system are necessary. However, conventional hydraulic actuator systems are difficult to apply to wearable robots. Also, they have nonlinearities because of the presence of hydraulic fluid in a single rod cylinder. Electric linear actuators resolve the problems of hydraulic systems. However, due to their low load capacity, they are not easy to apply to wearable robots. In this paper, a pump-controlled electro-hydraulic actuator (EHA) system that considers the disadvantages of the hydraulic actuator and electric actuator is proposed for a wearable robot. Initially, a locking circuit design is considered for the EHA to give the system load holding capacity. Based on the developed model, the adaptive sliding mode control (ASMC) scheme is designed to resolve the nonlinearity problem of changes in the dynamic system. The ASMC scheme is then modeled and verified with Simulink. In order to verify the performance of the proposed adaptive control with the model, experiments are conducted. The proposed EHA verifies that the ASMC reaches the target value well despite the existence of many model uncertainties.

scholarly journals Rugged and Compact Three-Axis Force/Torque Sensor for Wearable Robots

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2770
Author(s):  
Heeyeon Jeong ◽  
Kyungjun Choi ◽  
Seong Jun Park ◽  
Cheol Hoon Park ◽  
Hyouk Ryeol Choi ◽  
...  
Keyword(s):  
Simple Structure ◽  
Load Capacity ◽  
Artificial Muscle ◽  
High Load ◽  
Torque Sensor ◽  
Wearable Robot ◽  
Wearable Robots ◽  
Negative Electrodes ◽  
The Difference ◽  
High Load Capacity

In the field of robotics, sensors are crucial in enabling the interaction between robots and their users. To ensure this interaction, sensors mainly measure the user’s strength, and based on this, wearable robots are controlled. In this paper, we propose a novel three-axis force/torque sensor for wearable robots that is compact and has a high load capacity. The bolt and nut combination of the proposed sensor is designed to measure high-load weights, and the simple structure of this combination allows the sensor to be compact and light. Additionally, to measure the three-axis force/torque, we design three capacitance-sensing cells. These cells are arranged in parallel to measure the difference in capacitance between the positive and negative electrodes. From the capacitance change measured by these sensing cells, force/torque information is converted through deep neural network calibration. The sensing point can also be confirmed using the geometric and kinematic relation of the sensor. The proposed sensor is manufactured through a simple and inexpensive process using cheap and simply structured components. The performance of the sensor, such as its repeatability and capacity, is evaluated using several experimental setups. In addition, the sensor is applied to a wearable robot to measure the force of an artificial muscle.

scholarly journals Design and Control of a Polycentric Knee Exoskeleton Using an Electro-Hydraulic Actuator

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 211 ◽  
Author(s):  
Taesik Lee ◽  
Dongyoung Lee ◽  
Buchun Song ◽  
Yoon Su Baek
Keyword(s):  
Sliding Mode ◽  
Nonlinear Models ◽  
Load Capacity ◽  
High Energy ◽  
Plant Design ◽  
Hydraulic Actuator ◽  
Robot System ◽  
Hardware System ◽  
Exoskeleton Robot ◽  
And Control

An exoskeleton robot helps the wearer with mechanical forces by identifying the wearer’s intentions and requires high energy efficiency, sufficient load capacity, and a comfortable fit. However, since it is difficult to implement complex anatomical movements of the human body, most exoskeleton robots are designed simply, unlike the anatomy of real humans. This forces the wearer to accept the robot’s stiffness entirely, and to use energy inefficiently from the power source. In this paper, a simple 1 degree of freedom (DoF) structure, which was mainly used in the knees of exoskeleton robots, was designed with a polycentric (multi-axial) structure to minimize the misalignment between wearer and robot, so that torque transfer could be carried out efficiently. In addition, the overall robot system was constructed by using an electro-hydraulic actuator (EHA) to solve the problems of the energy inefficiency of conventional hydraulic actuators and the low load capacity of conventional electric actuators. After the configuration of the hardware system, the sliding mode controller was designed to address the EHA nonlinear models and the uncertainty of the plant design. This was configured as Simulink for the first verification, and the experiment was conducted by applying it to the actual model to demonstrate the performance of the sliding mode control. In this process, an optical rotary encoder was used as the main feedback sensor of the controller. The proposed polycentric knee exoskeleton robot system using the EHA was able to reach the desired target value well despite the presence of many model uncertainties.

scholarly journals Adaptive Backstepping Sliding Mode Control for Direct Driven Hydraulics

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 1
Author(s):  
Shuzhong Zhang ◽  
Tianyi Chen ◽  
Fuquan Dai
Keyword(s):  
Sliding Mode Control ◽  
Control Strategy ◽  
Sliding Mode ◽  
External Disturbance ◽  
High Energy ◽  
Hydraulic Actuator ◽  
Adaptive Backstepping ◽  
Mode Control ◽  
Adaptive Law ◽  
Backstepping Sliding Mode Control

Due to the advantages of high energy efficiency and environmental friendliness, the electro-hydraulic actuator (EHA) plays a vital role in fluid power control. One variant of EHA, double pump direct driven hydraulics (DDH), is proposed, which consists of double fixed-displacement pumps, a servo motor, an asymmetric cylinder and auxiliary components. This paper proposes an adaptive backstepping sliding mode control (ABSMC) strategy for DDH to eliminate the adverse effect produced by parametric uncertainty, nonlinear characteristics and the uncertain external disturbance. Based on theoretical analysis, the nonlinear system model is built and transformed. Furthermore, by defining the sliding manifold and selecting a proper Lyapunov function, the nesting problems (of the designed variable and adaptive law) caused by uncertain coefficients are solved. Moreover, the adaptive backstepping control and the sliding mode control are combined to boost system robustness. At the same time, the controller parameter adaptive law is derived from Lyapunov analysis to guarantee the stability of the system. Simulations of the DDH are performed with the proposed control strategy and proportional–integral–differential (PID), respectively. The results show that the proposed control strategy can achieve better position tracking and stronger robustness under parameter changing compared with PID.

scholarly journals Who's Leading This Dance?: Theorizing Automatic and Strategic Synchrony in Human-Exoskeleton Interactions

2021 ◽  
Vol 12 ◽  
Author(s):  
Gavin Lawrence Kirkwood ◽  
Christopher D. Otmar ◽  
Mohemmad Hansia
Keyword(s):  
Problem Solving ◽  
Research Agenda ◽  
Adaptive Behaviors ◽  
Future Research ◽  
Wearable Robot ◽  
Future Research Agenda ◽  
Wearable Robots ◽  
Methodological Challenges ◽  
Conceptual Paper ◽  
And Performance

Wearable robots are an emerging form of technology that allow organizations to combine the strength, precision, and performance of machines with the flexibility, intelligence, and problem-solving abilities of human wearers. Active exoskeletons are a type of wearable robot that gives wearers the ability to effortlessly lift up to 200 lbs., as well as perform other types of physically demanding tasks that would be too strenuous for most humans. Synchronization between exoskeleton suits and wearers is one of the most challenging requirements to operate these technologies effectively. In this conceptual paper, we extend interpersonal adaption theory (IAT) to the exoskeleton context and explicate (a) the antecedents that are most likely to shape synchrony in human-exoskeleton interactions, (b) automatic and strategic synchrony as adaptive behaviors in human-exoskeleton interactions, and (c) outcome variables that are especially important in these processes. Lastly, we offer a discussion of key methodological challenges for measuring synchrony in human-exoskeleton interactions and offer a future research agenda for this important area.

Autonomous Aerial Refueling Modeling and Dynamic Inversion Adaptive Sliding Mode Control

2013 ◽  
Vol 760-762 ◽  
pp. 1202-1206
Author(s):  
Xun Sun ◽  
Xin Guo Zhang
Keyword(s):  
Sliding Mode Control ◽  
Flight Control ◽  
Control Method ◽  
Sliding Mode ◽  
Adaptive Sliding Mode Control ◽  
Dynamic Inversion ◽  
Aerial Refueling ◽  
Adaptive Sliding Mode ◽  
Mode Control ◽  
And Performance

A dynamic inversion adaptive sliding mode flight control method for autonomous aerial refueling (AAR) is approved in this paper. The drogue model and refueling aircraft 6-DOF nonlinear model is built. In order to improve the flight control precision and performance, the dynamic inversion control method is used to design the flight control law. Fuzzy adaptive control is combined with the sliding mode control is used to compensate the error of inversion, so the robustness and transient characteristic performance could be improved. The simulation results show that the AAR flight control has excellent control performance.

A Study on Optimization Design and Performance Test of an Aerostatic Bearing

2012 ◽  
Vol 538-541 ◽  
pp. 3182-3186 ◽  
Author(s):  
Jen Sheng Shie ◽  
Ming Chang Shih
Keyword(s):  
Pressure Distribution ◽  
Optimization Design ◽  
Performance Test ◽  
Load Capacity ◽  
Low Flow ◽  
Aerostatic Bearing ◽  
Flow Rates ◽  
And Performance ◽  
High Load Capacity ◽  
Optimal Approach

This paper discusses about how to optimize design of an aerostatic bearing. In order to achieve the objective, there are four necessary qualifications: high load capacity, high stiffness, low flow rate and uniformly pressure distribution, those make an aerostatic bearing optimized. The finite difference method is employed to obtain the numerical solution of the pressure distribution between the surface of aerostatic bearing and worktable. The performance is determined by the pressure distribution of aerostatic bearing. Furthermore, this study proposed an integrated optimal approach that is HTGA/Gray. Comparing with many kinds of optimal theories finds out the most suitable parameters of an aerostatic bearing. Finally, the experimental results for the load capacities and flow rates clearly indicate that the proposed aerostatic bearing can enhance ability effectively.

scholarly journals Robust Control Optimization Based on Actuator Fault and Sensor Fault Compensation for Mini Motion Package Electro-Hydraulic Actuator

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2774
Author(s):  
Tan Van Nguyen ◽  
Huy Q. Tran ◽  
Khoa Nguyen Dang
Keyword(s):  
Sliding Mode ◽  
Unknown Input ◽  
Hydraulic Systems ◽  
Sensor Fault ◽  
Hydraulic Actuator ◽  
Research Attention ◽  
Control Optimization ◽  
Fault Compensation ◽  
Observer Model ◽  
The Difference

In recent years, electro-hydraulic systems have been widely used in many industries and have attracted research attention because of their outstanding characteristics such as power, accuracy, efficiency, and ease of maintenance. However, such systems face serious problems caused simultaneously by disturbances, internal leakage fault, sensor fault, and dynamic uncertain equation components, which make the system unstable and unsafe. Therefore, in this paper, we focus on the estimation of system fault and uncertainties with the aid of advanced fault compensation techniques. First, we design a sliding mode observer using the Lyapunov algorithm to estimate actuator faults that produce not only internal leakage fault but also disturbances or unknown input uncertainties. These faults occur under the effect of payload variations and unknown friction nonlinearities. Second, Lyapunov analysis-based unknown input observer model is designed to estimate sensor faults arising from sensor noises and faults. Third, to minimize the estimated faults, a combination of actuator and sensor compensation fault is proposed, in which the compensation process is performed due to the difference between the output signal and its estimation. Finally, the numerical simulations are performed to demonstrate the effectiveness of the proposed method obtained under various faulty scenarios. The simulation results show that the efficiency of the proposed solution is better than the traditional PID controller and the sensor fault compensation method, despite the influence of noises.

Design of Nonoverconstrained Energy-Efficient Multi-Axis Servo Presses for Deep-Drawing Applications1

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Francesco Meoni ◽  
Marco Carricato
Keyword(s):  
Energy Efficiency ◽  
Load Capacity ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Hydraulic Press ◽  
Ball Screw ◽  
Parallel Mechanisms ◽  
Modular Architecture ◽  
Servo Press ◽  
High Load Capacity

Servo-actuated presses may provide maximum pressing force at any ram position in the same manner that hydraulic presses do, while offering several benefits in terms of precision, energy-conversion efficiency, and simplicity, due to their lack of hydraulic circuitry and oil. Several press builders have developed servo-actuated presses; however, issues relating to overconstrained multi-axis architecture have been disregarded. This study proposes an innovative method to avoid overconstrained architectures in multi-axis presses, by implementing a family of modular parallel mechanisms that connect multiple servo-axes to the press ram. Parallel mechanisms, which can be applied in several fields of robotics and industrial automation, exhibit important benefits for the application at hand, including high-load capacity, stiffness, and compactness. A biaxial industrial servo press prototype with a nonoverconstrained and modular architecture was built and presented as a proof of concept. Each axis comprises a servomotor, a gearbox reducer, and a ball-screw transmission. It is shown that such a press may be constructed from commercially available components, achieving high energy efficiency and high press force with relatively simple construction. A direct comparison with an equivalent hydraulic-press model is carried out, thus highlighting the servo press energy efficiency.

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