scholarly journals Operator-Based Nonlinear Control for a Miniature Flexible Actuator Using the Funnel Control Method

Machines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 26
Author(s):  
Keisuke Ueno ◽  
Shuhei Kawamura ◽  
Mingcong Deng
Keyword(s):  
Nonlinear Control ◽  
Tracking Control ◽  
Control Method ◽  
Boundary Function ◽  
Soft Actuator ◽  
Design Scheme ◽  
Adaptive Law ◽  
Control Gain ◽  
Soft Actuators ◽  
Funnel Control

Recently, the studies of soft actuators have been getting increased attention among various fields. Soft actuators are very safe for fragile objects and have an affinity to humans because they are composed of flexible materials. A miniature flexible actuator is a kind of pneumatically driven soft actuator. It has a bellowed shape and asymmetrical structure. This shape can generate a curling motion in two ways under positive and negative pressures with only one air tube. In the previous article, a control system using adaptive λ-tracking control was proposed. This control gain can become too large as time tends to infinity because the adaptive law exhibits a non-decreasing gain. To solve this problem, the funnel control method is proposed. The adaptive gain of this method not only increases but also decreases; however, the design scheme of the boundary function which is needed to decide on adaptive gain is not proposed here. In this article, an operator-based nonlinear control system’s design and the design scheme of the boundary function using an observer are proposed. Then, the effectiveness of the proposed method is verified by a simulation and an experiment.

Soft Planar Actuator using Pneumatic-Rubber Balls

2000 ◽  
Vol 12 (3) ◽  
pp. 254-260 ◽  
Author(s):  
Toshiro Noritsugu ◽  
◽  
Daijyu Kaneshiro ◽  
Takashi Inoue
Keyword(s):  
Elastic Deformation ◽  
Silicone Rubber ◽  
Control Method ◽  
Fundamental Principle ◽  
Compressed Air ◽  
Rubber Tube ◽  
Carrier System ◽  
Soft Actuator ◽  
System A ◽  
Soft Actuators

The manipulation of fragile and shapeless objects requires an actuator with enough flexibility and safety not to injure manipulated objects. To cope with such requirements, soft actuators have been developed, most of which utilize elastic deformation of a rubber tube or balloon caused by compressed air pressure. Such a pneumatic rubber actuator is expected to be effectively used as a flexible and friendly soft actuator in various fields. In this study, to realize a flexible pneumatic carrier system, a soft planar actuator using rubber balls has been developed assuming that the actuator directly contacts carried objects. This paper describes a fundamental principle of operation, a control method and experimental results. Additionally, a small sized soft planar actuator made of silicone rubber is described. The results show the effectiveness of the proposed actuator mechanism.

Model Following Adaptive Sliding Mode Tracking Control Based on a Disturbance Observer for the Mechanical Systems

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Kun-Yung Chen
Keyword(s):  
Tracking Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Sliding Mode ◽  
Mechanical Systems ◽  
Time Varying ◽  
Adaptive Sliding Mode ◽  
Model Following ◽  
Control Gain ◽  
Mode Tracking

A model following adaptive sliding mode tracking control (MFASMTC) with the adjustable control gain based on a disturbance observer (DOB) for the mechanical system is proposed in this paper. The control gains of the proposed controller are automatically adjusted to compensate the unknown time-varying disturbances by the DOB. First, the unknown variables and uncertainties are lumped as the disturbance terms and the system dynamic model consist of the nominal matrix and disturbances vector. The desired model and sliding mode controller (SMC) are integrated by using the Lyapunov function candidate to obtain the general model following sliding mode tracking control (MFSMTC) with the fixed control gain. To stabilize and compensate the unknown time-varying disturbances for the control system, a DOB is combined with the MFSMTC to obtain the MFASMTC to automatically adjust the control gains. The mass-spring-damper system and two-link manipulator robot system are both used as examples system to demonstrate the proposed control scheme, respectively. The comparisons between MFSMTC with the fixed control gain and MFASMTC with the adjustable control gain based on a DOB are performed in this paper. From the simulation results, the proposed MFASMTC with the adjustable control gain based on a DOB demonstrates the stable and robust control performance for the unknown uncertainties and external disturbances. The proposed control method also can be applied to the other mechanical systems with the desired model to find the desired model following adaptive sliding mode tracking control.

scholarly journals A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

2021 ◽  
Vol 11 (13) ◽  
pp. 5865
Author(s):  
Muhammad Ahsan Gull ◽  
Mikkel Thoegersen ◽  
Stefan Hein Bengtson ◽  
Mostafa Mohammadi ◽  
Lotte N. S. Andreasen Struijk ◽  
...  
Keyword(s):  
Upper Limb ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Trajectory Tracking Control ◽  
Upper Limb Exoskeleton ◽  
And Performance ◽  
Physically Disabled People ◽  
Human Upper Limb

Wheelchair mounted upper limb exoskeletons offer an alternative way to support disabled individuals in their activities of daily living (ADL). Key challenges in exoskeleton technology include innovative mechanical design and implementation of a control method that can assure a safe and comfortable interaction between the human upper limb and exoskeleton. In this article, we present a mechanical design of a four degrees of freedom (DOF) wheelchair mounted upper limb exoskeleton. The design takes advantage of non-backdrivable mechanism that can hold the output position without energy consumption and provide assistance to the completely paralyzed users. Moreover, a PD-based trajectory tracking control is implemented to enhance the performance of human exoskeleton system for two different tasks. Preliminary results are provided to show the effectiveness and reliability of using the proposed design for physically disabled people.

Robust finite-time trajectory tracking control for a space manipulator with parametric uncertainties and external disturbances

2021 ◽  
pp. 095441002110147
Author(s):  
Qijia Yao
Keyword(s):  
Trajectory Tracking ◽  
Finite Time ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Parametric Uncertainties ◽  
External Disturbances ◽  
Trajectory Tracking Control ◽  
Space Manipulator ◽  
Tracking Controller

Space manipulator is considered as one of the most promising technologies for future space activities owing to its important role in various on-orbit serving missions. In this study, a robust finite-time tracking control method is proposed for the rapid and accurate trajectory tracking control of an attitude-controlled free-flying space manipulator in the presence of parametric uncertainties and external disturbances. First, a baseline finite-time tracking controller is designed to track the desired position of the space manipulator based on the homogeneous method. Then, a finite-time disturbance observer is designed to accurately estimate the lumped uncertainties. Finally, a robust finite-time tracking controller is developed by integrating the baseline finite-time tracking controller with the finite-time disturbance observer. Rigorous theoretical analysis for the global finite-time stability of the whole closed-loop system is provided. The proposed robust finite-time tracking controller has a relatively simple structure and can guarantee the position and velocity tracking errors converge to zero in finite time even subject to lumped uncertainties. To the best of the authors’ knowledge, there are really limited existing controllers can achieve such excellent performance under the same conditions. Numerical simulations illustrate the effectiveness and superiority of the proposed control method.

scholarly journals Application of a nonovershooting tracking control method for the Double Buck Converter

2020 ◽  
Vol 53 (2) ◽  
pp. 6151-6156
Author(s):  
Robert Schmid ◽  
Tony Srour ◽  
Johann Reger
Keyword(s):  
Tracking Control ◽  
Control Method ◽  
Buck Converter

scholarly journals Visual Tracking Control of Cable-Driven Hyper-Redundant Snake-Like Manipulator

2021 ◽  
Vol 11 (13) ◽  
pp. 6224
Author(s):  
Qisong Zhou ◽  
Jianzhong Tang ◽  
Yong Nie ◽  
Zheng Chen ◽  
Long Qin
Keyword(s):  
Visual Tracking ◽  
Tracking Control ◽  
Control Method ◽  
Adaptive Optimization ◽  
Tracking Errors ◽  
Kinematics Model ◽  
Compound Control ◽  
Original Intention ◽  
Control Scheme ◽  
Specific Geometry

The cable-driven hyper-redundant snake-like manipulator (CHSM) inspired by the biomimetic structure of vertebrate muscles and tendons, which consists of numerous joint units connected adjacently driven by elastic materials with hyper-redundant DOF, performs flexible kinematic skills and competitive compound capability under complicated working circumstances. Nevertheless, the drawback of lacking the ability to perceive the environment to perform intelligently in complex scenarios leaves a lot to be improved, which is the original intention to introduce visual tracking feedback acting as an instructor. In this paper, a cable-driven snake-like robotic arm combined with a visual tracking technique is introduced. A visual tracking approach based on dual correlation filter is designed to guide the CHSM in detecting the target and tracing after its trajectory. Specifically, it contains an adaptive optimization for the scale variation of the tracking target via pyramid sampling. For the CHSM, an explicit kinematics model is derived from its specific geometry relationships and followed by a simplification for the inverse kinematics based on some assumption or limitation. A control scheme is brought up to combine the kinematics with visual tracking via the processing tracking errors. The experimental results with a practical prototype validate the availability of the proposed compound control method with the derived kinematics model.

scholarly journals Fuzzy Adaptive Prescribed Performance Control for Uncertain Horizontal Platform System with Unknown Control Gain

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Wei Xiang ◽  
Yeguo Sun ◽  
Chunzhi Yang
Keyword(s):  
Control Method ◽  
Adaptive Controller ◽  
Performance Bounds ◽  
Constrained System ◽  
Prescribed Performance ◽  
Performance Technique ◽  
Control Gain ◽  
Unknown Control ◽  
Platform System ◽  
Fuzzy Adaptive

This paper proposes a fuzzy adaptive control method for uncertain horizontal platform system with unknown control gain, which is capable of guaranteeing the prescribed performance bounds. An error transformation is introduced to transform the original constrained system into an equivalent unconstrained one. Then, based on the error transformation technique and the predefined performance technique, a fuzzy adaptive controller is designed for the unconstrained system. It is shown that all the variables of the resulting closed-loop system are bounded. Finally, an illustrative example is given to demonstrate the effectiveness and usefulness of the proposed method.

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