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 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 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 Development and Control of an Electro-Hydraulic Actuator System for an Exoskeleton Robot

2019 ◽  
Vol 9 (20) ◽  
pp. 4295 ◽  
Author(s):  
Dongyoung Lee ◽  
Buchun Song ◽  
Sang Yong Park ◽  
Yoon Su Baek
Keyword(s):  
Gait Cycle ◽  
Sliding Mode ◽  
Control Valve ◽  
Hydraulic Cylinder ◽  
Hydraulic Actuator ◽  
Directional Control ◽  
Robot Systems ◽  
Actuator System ◽  
And Control ◽  
Directional Control Valve

Exoskeleton robots have been developed in various fields and are divided into electric and hydraulic exoskeletons according to the actuator type. In the case of hydraulic robots, because a unidirectional pump is applied, there are limitations to the wearer’s walking. In addition, robot systems are complicated, because a directional control valve is required to change the direction of the actuator. To solve these problems, we designed the electro-hydraulic actuator (EHA) system which has both the hydraulic and electric advantages. The EHA system consists of a hydraulic bidirectional pump, a motor, a hydraulic cylinder, and various valves. For the development of the piston pump, we analyzed the gait cycle and considered the flow rate and pulsation rate. In order to reduce the size and weight of the EHA system, the valves were made from one manifold, and the hydraulic circuit was simplified. We verified that the developed EHA system is applicable to robots through position and force control experiments. Because the hydraulic system is nonlinear, we designed a sliding mode control (SMC) and compared it with the proportional integral derivative (PID) controller.

Modeling and control of a novel facade cleaning robot with four-ducted fan drive

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142098572
Author(s):  
Xiao-Peng Li ◽  
Xin Wang ◽  
Bin Feng
Keyword(s):  
Sliding Mode ◽  
Load Capacity ◽  
Modeling And Control ◽  
Ducted Fan ◽  
Cleaning Robot ◽  
Modern Cities ◽  
Movement Mechanism ◽  
Stable Performance ◽  
Cleaning Robots ◽  
And Control

With the development of modern cities, the demand for cleaning glass curtain walls in urban skyscrapers is increasing, and therefore, many researches on facade cleaning robots have been carried out in the past few decades. In this article, a novel type of facade cleaning robot based on four-ducted fan is proposed. To improve the load capacity of the robot, the lifting and horizontal movement are, respectively, supported by an independent lifting mechanism and a lateral movement mechanism. Unlike the previous passive and active suction, the powerful suction power of the robot is provided by the four-ducted fan. Meanwhile, the obstacle-climbing force is caused by the forward of the four-ducted fan that improves the crossing obstacle ability. In addition, an incremental sliding mode algorithm is applied for controlling the posture when the robot crosses obstacles, which can ensure the stable performance of the cleaning robot under disturbance. Some simulations and experiments are conducted and the results demonstrate the effectiveness and robustness of the designed facade cleaning robot.

Novel Adaptive Reaching Law for Sliding Mode Control of an Upper Limb Exoskeleton Robot*

2020 ◽  
Author(s):  
Brahim Brahmi ◽  
Khaled El-Monajjed ◽  
Mohammad Habibur Rahman ◽  
Tanvir Ahmed ◽  
Claude El-Bayeh ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Upper Limb ◽  
Sliding Mode ◽  
Reaching Law ◽  
Mode Control ◽  
Upper Limb Exoskeleton ◽  
Exoskeleton Robot

Integral barrier Lyapunov functions-based integrated guidance and control design for strap-down missile with field-of-view constraint

2021 ◽  
pp. 014233122098132
Author(s):  
Bin Zhao ◽  
Zhenxin Feng ◽  
Jianguo Guo
Keyword(s):  
Sliding Mode ◽  
State Equation ◽  
Field Of View ◽  
Feedback Form ◽  
Theoretical Derivation ◽  
Guidance And Control ◽  
Integrated Guidance And Control ◽  
Twisting Algorithm ◽  
And Control ◽  
Special Time

The problem of the integrated guidance and control (IGC) design for strap-down missile with the field-of-view (FOV) constraint is solved by using the integral barrier Lyapunov function (iBLF) and the sliding mode control theory. Firstly, the nonlinear and uncertainty state equation with non-strict feedback form for IGC design is derived by using the strap-down decoupling strategy. Secondly, a novel adaptive finite time disturbance observer is proposed to estimate the uncertainties based on an improved adaptive gain super twisting algorithm. Thirdly, the special time-varying sliding variable is designed and the iBLF is employed to handle the problem of FOV constraint. Theoretical derivation and simulation show that the IGC system is globally uniformly ultimately bounded and the FOV angle constraint is also guaranteed not only during the reaching phase but also during the sliding mode phase.

scholarly journals Current Knowledge and Future Directions for Improving Subsoiling Quality and Reducing Energy Consumption in Conservation Fields

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 575
Author(s):  
Shangyi Lou ◽  
Jin He ◽  
Hongwen Li ◽  
Qingjie Wang ◽  
Caiyun Lu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Cover Crops ◽  
Current Knowledge ◽  
High Energy ◽  
Field Application ◽  
Research Progress ◽  
Monitoring And Control ◽  
Future Directions ◽  
Tillage Depth ◽  
And Control

Subsoiling has been acknowledged worldwide to break compacted hardpan, improve soil permeability and water storage capacity, and promote topsoil deepening and root growth. However, there exist certain factors which limit the wide in-field application of subsoiling machines. Of these factors, the main two are poor subsoiling quality and high energy consumption, especially the undesired tillage depth obtained in the field with cover crops. Based on the analysis of global adoption and benefits of subsoiling technology, and application status of subsoiling machines, this article reviewed the research methods, technical characteristics, and developing trends in five key aspects, including subsoiling shovel design, anti-drag technologies, technologies of tillage depth detection and control, and research on soil mechanical interaction. Combined with the research progress and application requirements of subsoiling machines across the globe, current problems and technical difficulties were analyzed and summarized. Aiming to solve these problems, improve subsoiling quality, and reduce energy consumption, this article proposed future directions for the development of subsoiling machines, including optimizing the soil model in computer simulation, strengthening research on the subsoiling mechanism and comprehensive effect, developing new tillage depth monitoring and control systems, and improving wear-resisting properties of subsoiling shovels.

Design of M-G modal space sliding mode control for lower limb exoskeleton robot driven by electrical actuators

Mechatronics ◽  
2021 ◽  
Vol 78 ◽  
pp. 102610
Author(s):  
Jinsong Zhao ◽  
Tao Yang ◽  
Zhilei Ma ◽  
Chifu Yang ◽  
Zhipeng Wang ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Sliding Mode ◽  
Lower Limb Exoskeleton ◽  
Mode Control ◽  
Exoskeleton Robot ◽  
Modal Space

scholarly journals An extended state observer-based full-order sliding mode control for robotic joint actuated by antagonistic pneumatic artificial muscles

2021 ◽  
Vol 18 (1) ◽  
pp. 172988142098603
Author(s):  
Daoxiong Gong ◽  
Mengyao Pei ◽  
Rui He ◽  
Jianjun Yu
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
State Observer ◽  
Extended State Observer ◽  
Artificial Muscles ◽  
Extended State ◽  
Robot System ◽  
Mode Control ◽  
Physical Experiments ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are expected to play an important role in endowing the advanced robot with the compliant manipulation, which is very important for a robot to coexist and cooperate with humans. However, the strong nonlinear characteristics of PAMs hinder its wide application in robots, and therefore, advanced control algorithms are urgently needed for making the best use of the advantages and bypassing the disadvantages of PAMs. In this article, we propose a full-order sliding mode control extended state observer (fSMC-ESO) algorithm that combines the ESO and the fSMC for a robotic joint actuated by a pair of antagonistic PAMs. The fSMC is employed to eliminate the chattering and to guarantee the finite-time convergence, and the ESO is adopted to observe both the total disturbance and the states of the robot system, so that we can inhibit the disturbance and compensate the nonlinearity efficiently. Both simulations and physical experiments are conducted to validate the proposed method. We suggest that the proposed method can be applied to the robotic systems actuated by PAMs and remarkably improve the performance of the robot system.

scholarly journals Overfeeding Extends the Period of Annual Cyclicity but Increases the Risk of Early Embryonic Death in Shetland Pony Mares

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 361
Author(s):  
Nicky M. M. D’Fonseca ◽  
Charlotte M. E. Gibson ◽  
Iris Hummel ◽  
David A. van Doorn ◽  
Ellen Roelfsema ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Reproductive Activity ◽  
High Energy ◽  
Morphometric Parameters ◽  
Net Energy ◽  
Conceptus Development ◽  
And Control ◽  
Annual Duration ◽  
Embryonic Death

Obesity has been associated with altered reproductive activity in mares, and may negatively affect fertility. To examine the influence of long-term high-energy (HE) feeding on fertility, Shetland pony mares were fed a diet containing 200% of net energy (NE) requirements during a three-year study. The incidence of hemorrhagic anovulatory follicles (HAF) and annual duration of cyclicity were compared to those in control mares receiving a maintenance diet. Day-7 embryos were flushed and transferred between donor and recipient mares from both groups; the resulting conceptuses were collected 21 days after transfer to assess conceptus development. HE mares became obese, and embryos recovered from HE mares were more likely to succumb to early embryonic death. The period of annual cyclicity was extended in HE compared to control mares in all years. The incidence of HAFs did not consistently differ between HE and control mares. No differences in embryo morphometric parameters were apparent. In conclusion, consuming a HE diet extended the duration of cyclicity, and appeared to increase the likelihood of embryos undergoing early embryonic death following embryo transfer.

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