Motion Of Actuator Research Articles

Development of an in-situ mechanical property identification system for use in high radiation fields

ABSTRACT An in-situ mechanical property identification system is required for easy-to-identify mechanical properties, such as fuel debris and rubble, in high-radiation fields. This is necessary for planning fuel debris removal, a central issue in the decommissioning work of the Fukushima Daiichi Nuclear Power Station. Because of the high-radiation field inside PCV and RPV, it is difficult to use high-performance analytical equipment with semiconductor circuits. This study is for the first step in a technical solution to realize the conceptual design of an in-situ mechanical property identification system. A simple in-situ mechanical property identification system that combined electrical and mechanical components with relatively high radiation resistance was developed. The exploration unit of the system placed in a high-radiation field was composed of a thin drill, drill motor, and hydraulic actuator. The remote-controlled unit of the system could identify material types from data obtained by the power load of the drill motor and the repulsive force of the drill using a machine-learning model. Preliminary experiments were conducted to investigate the effectiveness of the system for metal samples with different hardness values. This study presents technical ideas for the conceptual design of an in-situ mechanical property identification system for use in the high-radiation fields.

Application of Soft Grippers in the Field of Agricultural Harvesting: A Review

This review summarizes the important properties required for applying soft grippers to agricultural harvesting, focusing on their actuation methods and structural types. The purpose of the review is to address the challenges of limited load capacity and stiffness, which significantly hinder the broader application of soft grippers in agriculture. This paper examines the research progress on variable stiffness methods for soft grippers over the past five years. We categorize various variable stiffness techniques and analyze their advantages and disadvantages in enhancing load capacity, stiffness, dexterity, degree of integration, responsiveness, and energy consumption of soft grippers. The applicability and limitations of these techniques in the context of agricultural harvesting are also discussed. This paper concludes that combined material variable stiffness technology with a motor actuation claw structure in soft grippers is better suited for agricultural harvesting operations of woody crops (e.g., apples, citrus) and herbaceous crops (e.g., tomatoes, cucumbers) in unstructured environments.

Modeling and Control Experiments of a Fishtail-Like Pneumatic Soft Actuator

As the exploration of deep-sea resources continues, underwater actuators with conventional motors as the main building blocks can no longer meet the increasingly demanding needs. Inspired by bionics, researchers have started to work on underwater actuators with bionic structures. In this study, we designed and implemented a novel Fishtail-like Pneumatic Soft Actuator (FPSA). This innovative actuator configuration is inspired by the tail structure of Body and/or Caudal Fin (BCF) mode fish. The actuator's motion is achieved by controlling the expansion and contraction of the pneumatic soft muscles on both sides. And by constructing an experimental platform, we conducted an in-depth performance characterization, revealing the existence of a frequency-dependent nonlinear hysteresis characteristic of the FPSA. In order to accurately characterize this property, we built a dynamic model of the FPSA and successfully identified the uncertain parameters in the model by applying the nonlinear least squares method. The validation results show that the constructed model can accurately describe the nonlinear hysteresis characteristics of the FPSA. Finally, we successfully realized the high-precision trajectory tracking control of the endpoint of the FPSA using a PID controller. This result provides relevant ideas for the research of novel underwater bionic actuators.

Experimental optimal control of servo-pneumatic with sliding mode and GA-fuzzy-PID-PWM

Due to the inherent nonlinearity of pneumatic systems, achieving accurate control of pneumatic actuators remains a challenging task. This study compares three control strategies-PID control, fuzzy control, and sliding mode control-used to guide the motion of pneumatic actuators driven by on/off solenoid valves. The primary objective is to evaluate and compare the performance of each controller in the context of servo-pneumatic systems, highlighting their respective advantages and disadvantages. On/off solenoid valves, which reduce system costs, are utilized in this study. Since these valves can only process on/off signals, pulse width modulation (PWM) is employed to modulate the input signal, adjusting the duty cycle and performance time of the valves. Initially, the governing equations for the actuator and valves are presented, followed by an introduction to each controller. The pulse width modulation algorithm is then discussed, which regulates the control signal to the valve’s duty cycle and performance time. Finally, simulation results are provided, comparing the controllers and illustrating their strengths and weaknesses.

Latissimus-dorsi-inspired wire mechanism for improving energy efficiency of quadruped robot locomotion

A spine, flexible structure in the trunk, improves the locomotion energy efficiency of the quadruped robot. However, improving energy efficiency remains a significant challenge for quadruped robots seeking long-duration operations. This study introduces a wire mechanism that converts active spine flexion into the forelimb propulsive motion, improving energy efficiency during locomotion through spine flexion-extension shape change. Quasi-static force simulations and static force measurements with a developed robot confirm that the proposed mechanism increases the force generated at the forelimb foot. Furthermore, robot-running experiments demonstrates that the robot with the proposed mechanism runs more energy efficiently. These results support the proposed mechanism's effectiveness in improving energy efficiency in locomotion with spine flexion-extension shape change.

Design and kinematic analysis of cable-driven underactuated manipulator on spacecraft

Cable-driven manipulators present significant dexterity and compliance in highly complex environments, which shows potential advantages for its application in the aerospace engineering. However, the application of the manipulators is still constrained by their inherent limitations, such as the large size and mass of the driving base, low load capacity and nonlinear complex models. In this paper, we design a novel cable-driven underactuated manipulator (CDUM) with high load capacity and less actuator motor, and propose a multi-level kinematic model for the proposed CDUM. The CDUM with 7 degrees of freedom is driven by three motors, which is composed of two segments. The segment 2 is capable of both telescoping and rotational movements, which is driven by two cables. To enhance its load capacity, a novel worm joint is designed for segment 1. Moreover, the joints of each segment can move with equal rotation angle and translational displacement by utilizing synchronous mechanism. Based on the structural features of the manipulator, the multi-level kinematics from the actuator variables to manipulator end-effector are expounded, including the actuator-joint kinematics and joint-end kinematics. Especially, the decoupled kinematic equation is derived to illustrate the coupling motion principle between joint variables of a single joint of segment 2. Finally, computational simulations are conducted to analyze the performance of the proposed mechanism and verify the method proposed in this work. The numerical results demonstrate that the cable-driven manipulator moves smoothly and the proposed nonlinear kinematics model is effective.

DEVELOPMENT AND APPLICATION OF STEER-BY-WIRE (SBW) WITH LINEAR SENSORS TO A SMALL ELECTRIC VEHICLE

A steer-by-wire (SBW) system with linear sensors has been developed and implemented on a small electric vehicle (EV). This system comprises a steering wheel, an angle and torque sensor, a wheel angle feedback sensor, an electric motor actuator, linkages, and a controller. It is specifically designed to electrically control the wheel angles without utilizing a conventional steering gearbox. The electric actuator motor is mounted on the steering mechanism and directly connected to the left and right wheel knuckles via linkages. Two linear sensors are employed: one located on the steering wheel to generate steering wheel angle signal , and the other installed on the wheel knuckle mechanism to produce front wheel angle feedback signal . When the driver rotates the steering wheel, the controller calculates the pitch error based on inputs from the two linear sensors and subsequently adjusts the wheel angles by powering the electric motor actuator. Experimental testing revealed a response time of 0.3 seconds, with the pitch error maintained within an angle of less than 3° during straight-motion tests. During cornering motion tests, the measured backlash was approximately 0.06 rad, demonstrating the system's responsive performance. This SBW technology with linear sensors is anticipated to reduce system complexity while enhancing precision, accuracy, and response speed of wheel angle adjustments to steering inputs, effectively meeting driving requirements.

Adjusted linear quadratic regulator-proportional-derivative control of Quanser’s three degrees of freedom helicopter based on flower pollination algorithm under external disturbances

External disturbances, saturation of actuator motors, and limits of certain angular movements are commonly encountered in robotic systems, particularly those involving flight, and they present the most common and influential factors affecting the stability and performance of these systems. In this paper, a hybrid controller for a three-degree-of-freedom (3-DoF) helicopter is designed and applied to this flying robot system, taking into account the previously mentioned constraints. The proposed hybrid controller integrates proportional-derivative (PD) control with an adjusted linear quadratic regulator (ALQR) using the flower pollination algorithm (FPA) optimization method. Simulation results of travel (λ), elevation (ε), and pitch (ρ) responses, as well as experimental results of elevation and travel tracking responses under external disturbances using the bench-top Quanser’s (3-DoF) helicopter, demonstrate the robustness and good performance of the controlled system using the proposed method. The effectiveness of the proposed method is compared to several methods in the literature.

Dynamics and Collective Behavior of Chemically Propelled Janus Sphere Dimers in Complex Solvents.

The propulsion mechanisms and collective dynamics of chemically powered Janus sphere dimers at the micro- and nanoscales, confined in a quasi-two-dimensional geometry, are investigated using a coarse-grained microscopic dynamical model. These active Janus dimers consist of two identical Janus spheres, featuring a catalytic cap on one hemisphere. The chemical reaction taking place on the catalytic surface generates asymmetric concentration gradients of product molecules around the Janus sphere, leading to the self-propulsion of the dimers. Depending on the dimer configuration, they exhibit various motion behaviors such as forward propulsion, rotation, and restricted stochastic motion. Due to chemotactic effects and self-diffusiophoretic forces, ensembles of dimers spontaneously form diverse structures, such as transient clusters, stable rotational ensembles, and antiparallel aligned doublets. This study demonstrates that the configurations of Janus sphere dimers significantly influence their self-propulsion and collective behaviors, providing crucial insights for the design and control of active micro- and nanoscale systems.

MXene Hybridized Polymer with Enhanced Electromagnetic Energy Harvest for Sensitized Microwave Actuation and Self-Powered Motion Sensing

HighlightsAn alternative electromagnetic attenuation pathway is proposed in the MXene-polymer hybrid structure, distinct from conduction loss, for generalizing the results to a wider range of electromagnetic-thermal driven soft materials and devices.By efficiently harvesting and converting electromagnetic energy, the response time of the hybrid polymer to microwave exhibits 87% reduction with merely 0.15 wt% MXene.A new mode of self-powered motion sensing based on deformation-driven piezoelectric effect is developed, enhancing the material’s intelligence.

Collaborative actuation of liquid crystal elastomer unit cells as a function design platform

AbstractAs future soft robotic devices necessitate a level of complexity surpassing current standards, a new design approach is needed that integrates multiple systems necessary to synchronize the motions of soft actuators and the response of signals, thereby enhancing the intelligence of flexible devices. Herein, we propose a liquid crystal elastomer unit cell-based platform that organizes the cells in a group to create expandable functions. One unit cell behaves like a flexible module that can expand biaxially into a specific, stable, and controllable pattern. Collaborating the unit cells in different manners results in an adaptable soft grasper, a half-adder for information processing, and a tunable phononic bandgap. This implies a high level of reconfigurability and scalability in both structures and functions by elegantly reassembling the unit cells. This design strategy has the potential to integrate multiple functions that traditional soft actuators cannot accommodate, providing a platform for developing intelligent soft robotics.

Direct adaptive neural control for precision piezoelectric actuator without hysteresis compensation

This paper introduces a novel Direct Adaptive Neural Control (DANC) approach to enhance the precision of piezoelectric actuator motion control significantly. By effectively addressing the complexities of hysteresis, DANC simplifies system design while delivering superior performance. A Radial Basis Function Neural Network (RBFNN) is employed to handle system uncertainties robustly, and a switching control mechanism guarantees stability, rigorously verified through Lyapunov analysis. Experimental results using a Thorlabs PZS001 actuator convincingly demonstrate substantial performance improvements over conventional PID control, the feedforward-based neural network and feedback control (FF-FB control).

Pengaruh Penyesuaian Parameter Membership Function pada Sistem Kendali Robot Balancing Berbasis Fuzzy Logic

This research develops a balancing robot control system using a fuzzy logic approach, focusing on the adjustment of membership function parameters. The main components of the system include the ESP32 microcontroller, MPU6050 sensor for detecting tilt angle and angular velocity, and L298 motor driver for DC motor actuation. Triangular-shaped membership functions are implemented, and parameters a, b, and c are adjusted through simulation to enhance system performance. Evaluation results indicate an average settling time of 1.2 seconds, a maximum overshoot of 5%, and a steady-state error of less than 2 degrees. This adjustment successfully balances response speed and stability, providing important guidance for developers in designing a more optimal fuzzy logic control system. The research was conducted at the Electrical Engineering Laboratory of 17 August 1945 University (Untag) Surabaya from June to December 2023.

Snap-through mechanism of an elastic bimetal ring for rotary actuation

Smart materials responsive to stimuli and new rotary mechanisms have drawn much attention in recent years. This paper investigates a novel snap-through rotation mechanism of a thermal responsive bimetal ring confined inside the annular region constraint when subjected to the local curvature induced by thermal loading. The buckled ring has movable boundaries and keeps an invariant shape during the snap-through rotation so that it requires small energy input to drive the bistable transition. To uncover the elusive mechanism behind this intriguing snap-through phenomenon, a theory based on the bifurcation and energy principle is developed to predict the critical loading curvature and the critical loading temperature, which agrees with the experimental results. The effects of loading positions and the constraint width are studied and a map predicting the critical loading curvature with different geometrical parameters is demonstrated. The rotary buckled ring not only enables the bistable actuation, but also triggers various actuation applications such as the motor actuation and the pump actuation. Due to great advantages in terms of energy supply and actuation loading, this study exhibits great potential of the proposed snap-through mechanism in bistable structures and rotary actuation.

Event-triggered finite-time adaptive neural network control for quadrotor UAV with input saturation and tracking error constraints

In this article, an event-triggered finite-time adaptive neural network control tracking strategy is proposed for quadrotor unmanned aerial vehicle (UAV) with input saturation and error constraints. Firstly, the radial basis function neural networks (RBFNNs) are adopted to identify the unknown uncertainty of quadrotor UAV model from the installation errors, gyroscope errors and so on. An auxiliary equation is constructed to deal with input physical saturation from the actuator motors. Additionally, by combining the performance function and error transformation, the issue of error constraint is solved. Based on the Lyapunov stability theory and event-triggered mechanisms, a finite-time adaptive neural network scheme is developed to ensure that the closed-loop quadrotor UAV system is semi-globally practically finite-time stable, and save the computation, resources, and transmission load. Finally, the simulation results illustrate the good tracking performance of quadrotor UAV by using the proposed control strategy.

Backward motion suppression in space-constrained piezoelectric pipeline robots

In response to the current challenges of detecting micro pipelines, a micro pipeline robot based on the principle of piezoelectric inertia stick-slip drive was proposed in this paper, which can be effectively applied to the detection and maintenance of micro pipelines. However, during the analysis of the robot's displacement trajectory, it was observed that using inertial drive could cause the backward motion of the robot. This may adversely affect the accuracy and stability of the robot's operation within the micro pipelines. Therefore, a novel control method is derived from the original pipeline robot structure. By affixing piezoelectric sheets to the driving feet of the robot to adjust their deformation and subsequently employing collaborative control of piezoelectric sheets and piezoelectric stacks to regulate friction between the driving feet and the pipe wall, the backward motion of the robot was effectively mitigated. Compared to existing backward motion suppression methods, the approach proposed in this paper has a minimal impact on the actuator's size, allowing for flexible adaptation to various space-constrained applications, while also offering the advantage of a simple control strategy. After determining the structure and working principle, deformation analysis of the driving foot and dynamic simulation analysis of the driving system were conducted. These analyses provide insights into the relationship between mechanical and electrical parameters and output performance within the driving system, thereby validating the feasibility of the control method. Subsequently, a prototype was fabricated, and its output performance was tested. Results demonstrate that this control method can effectively suppress inertial backward motion, achieving a suppression rate close to 100 %. This research presents a novel idea and methodology for mitigating the backward motion of piezoelectric inertial stick-slip actuators with driving foot structures.

Measurement method of flexible component pose based on discrete motion actuators

Abstract In order to address the limitations of traditional large discrete motion actuator mechanisms in realizing high-precision inter-axis relationship calibration in manufacturing environments, this paper proposes a new convolutional neural network-based attitude mapping estimation method, component pose using convolutional neural network (CPCNN). The method implicitly encodes the inter-axis relation matrix into the weight parameters of the training neural network, which results in a high degree of integration with existing large discrete motion actuator mechanisms. The CPCNN-based method directly obtains the attitude change of the adjustment cabin by reading the change of each axis of the current motion actuator mechanism in its own coordinate system. This method can overcome the limitations of the experimental process in the traditional calibration methods and improve the accuracy of attitude mapping under the influence of self-weight by selecting better motion parameters through redundant degrees of freedom. The application of this new method will provide an effective solution for the high-precision inter-axis relationship calibration of large discrete motion actuator mechanisms in manufacturing environments, offering new possibilities for improving production efficiency and product quality.

Achieving Stable and Effective Stick-Slip Motions of Piezoelectric Actuators With a Small Mass Rotor by Means of the Auxiliary Friction

Achieving Stable and Effective Stick-Slip Motions of Piezoelectric Actuators With a Small Mass Rotor by Means of the Auxiliary Friction

Adaptive Neural Control for Hysteretic Nonlinear Systems With Hysteresis Neural Direct Inverse Compensator and Its Application.

Aiming at high precision control for a class of hysteretic nonlinear systems, a new hysteresis direct inverse compensator-based adaptive output feedback control scheme is designed in this article. First, a novel long short-term memory neural network (LSTMNN)-based hysteresis inverse compensator is established to compensate the asymmetric hysteresis nonlinearity, where the LSTMNN is used as the prediction mechanism for model operator weights, rather than the overall mapping of hysteresis input and output. Second, by designing the modified high-gain K-Filter states observer and the error transformed function, the unmeasurable states are estimated with arbitrarily small estimation error and the prespecified tracking performance is achieved. Lastly, the biconical dielectric elastomer actuator (DEA) motion platform is constructed. Then, the effectiveness of the proposed LSTMNN-based hysteresis inverse compensator and control scheme are verified on the experimental platform. The experimental results illustrate the effectiveness and advantages of proposed control scheme.

Compact advanced pure tilt actuator for testing tilt-to-length coupling in space-based gravitational wave detection.

Tilt-to-length (TTL) coupling, caused by the jitter of test masses or satellites, is a major noise source in space-based gravitational wave detection. Calibrating and suppressing TTL coupling noise at the sub-nanometer level is essential. A key challenge in current ground-based TTL coupling testing is the residual translational movement of the tilt actuator. This paper presents the development of a compact advanced pure tilt actuator (APTA) specifically designed for testing TTL coupling. The APTA enables precise tilt motion, monitored by a four-beam interferometer measuring the displacement of attached retroreflectors. Detailed theoretical models and experimental setups are given. Experimental results demonstrate that the APTA test bed can achieve sub-nanometer-level TTL coupling calibration. Additionally, a typical test-mass interferometer tested by the APTA test bed demonstrated that the imaging system effectively suppresses TTL coupling errors. The TTL coupling coefficients were reduced from over ±30 μm/rad to within ±5 μm/rad across a range of ±200 μrad. The APTA test bed offers a compact, high-precision solution for ground-based TTL coupling tests and has the potential for broader application in related experimental setups.