Actuator Mechanisms Research Articles

Harnessing Deep Learning of Point Clouds for Morphology Mimicking of Universal 3D Shape‐Morphing Devices

Shape‐morphing devices, a crucial branch in soft robotics, hold significant application value in areas like human–machine interfaces, biomimetic robotics, and tools for biological systems. To achieve 3D programmable shape morphing (PSM), the deployment of array‐based actuators is essential. However, a critical knowledge gap in 3D PSM is controlling the complex systems formed by these soft actuator arrays to mimic the morphology of the target shapes. This study, for the first time, represents the configuration of shape‐morphing devices using point cloud data and employing deep learning to map these configurations to control inputs. Shape Morphing Net (SMNet), a method that realizes the regression from point cloud to high‐dimensional control input vectors, is proposed. It has been applied to 3D PSM devices with three different actuator mechanisms, demonstrating its universal applicability to inversely reproduce the target shapes. Further, applied to previous 2D PSM devices, SMNet significantly enhances control precision from 82.23% to 97.68%. In the demonstrations of morphology mimicking, 3D PSM devices successfully replicate arbitrary target shapes obtained either through 3D scanning of physical objects or via 3D modeling software. The results show that within the deformable range of 3D PSM devices, accurate reproduction of the desired shapes is achievable.

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.

Self-deployable hinges for monolithic space structures using multi-material additive manufacturing

Deployable structures inspired by origami have gained significant prominence in space applications, including solar arrays, reflector arrays, and satellite antennas. Traditionally, these structures consist of separate components that are folded during launch and later deployed in space using springs or actuator mechanisms. However, recent advancements in multi-material additive manufacturing have opened new possibilities for the fabrication of monolithic structures, integrating deployable mechanisms into a single entity. In this paper, we present a novel framework for designing unidirectional (UD) and bidirectional (BD) hinges utilizing viscoelastic materials, incorporated into rigid plates, forming deployable structures. These hinges exhibit the unique ability to store strain energy upon deformation and self-deploy to a flat configuration when released. The experimental results presented here demonstrate the effectiveness and feasibility of our hinge designs in real-world applications. To demonstrate the practical applicability of these hinge designs, we construct a Repeating Unit Cell (RUC) of a large origami-inspired deployable structure, showcasing their compatibility with popular deployable structure patterns.

Insect-scale jumping robots enabled by a dynamic buckling cascade

Millions of years of evolution have allowed animals to develop unusual locomotion capabilities. A striking example is the legless-jumping of click beetles and trap-jaw ants, which jump more than 10 times their body length. Their delicate musculoskeletal system amplifies their muscles' power. It is challenging to engineer insect-scale jumpers that use onboard actuators for both elastic energy storage and power amplification. Typical jumpers require a combination of at least two actuator mechanisms for elastic energy storage and jump triggering, leading to complex designs having many parts. Here, we report the new concept of dynamic buckling cascading, in which a single unidirectional actuation stroke drives an elastic beam through a sequence of energy-storing buckling modes automatically followed by spontaneous impulsive snapping at a critical triggering threshold. Integrating this cascade in a robot enables jumping with unidirectional muscles and power amplification (JUMPA). These JUMPA systems use a single lightweight mechanism for energy storage and release with a mass of 1.6 g and 2 cm length and jump up to 0.9 m, 40 times their body length. They jump repeatedly by reengaging the latch and using coiled artificial muscles to restore elastic energy. The robots reach their performance limits guided by theoretical analysis of snap-through and momentum exchange during ground collision. These jumpers reach the energy densities typical of the best macroscale jumping robots, while also matching the rapid escape times of jumping insects, thus demonstrating the path toward future applications including proximity sensing, inspection, and search and rescue.

Design, characterisation and validation of a haptic interface based on twisted string actuation.

This paper presents the design and experimental characterisation of a wrist haptic interface based on a twisted string actuator. The interface is designed for controlled actuation of wrist flexion/extension and is capable of rendering torque feedback through a rotary handle driven by the twisted string actuator and spring-loaded cable mechanisms. The interface was characterised to obtain its static and dynamic haptic feedback rendering capabilities. Compliance in the spring and actuation mechanism makes the interface suitable for smooth rendering of haptic feedback of large magnitudes due to the high motion transmission ratio of the twisted strings. Haptic virtual wall rendering capabilities are demonstrated.

DYNAMICS OF PNEUMATIC DRIVE. LECTURE CYCLE. OPTIMIZATION METHODS FOR SERVO PNEUMATIC DRIVES

The paper considers the main problems of optimal design associated with the choice of optimal parameters that affect both the static and dynamic characteristics of the pneumatic servo drives – control and actuator mechanisms. The possibility of using one decisive criterion (objective function) is shown, which provides the determination of optimal parameters of a pneumatic actuator with forward and rotational movement of the output link, as well as its application in the synthesis of a servo pneumatic cylinder. To calculate the parameters of the servo pneumatic actuator that are close to optimal, a two-criteria LPt-search was applied. It is shown and the corresponding conclusion is made that the proposed objective function can be used in the synthesis of tracking pneumatic/hydraulic drives with forward and rotational motion of the output link. In addition, the objective function for a drive with an energy source is given. The choice of optimal values of the parameters of the digital PID controller to eliminate self-oscillation in systems, as well as optimization of the type of transients of the tracking pneumatic drive is considered. The reason for the study was the problem of the occurrence of self-oscillations in pneumatic systems when using friction models that are closest to real ones. The transition from an analog (continuous) system to a digital (discrete) one is shown and performed, for which it is necessary to determine the sampling period. The paper specifies the main methods for determining the sampling period and shows the disadvantages of these methods. Its described of the criteria definition allowing to choose the optimum parameters of the actuator piston seal. As criteria, it is proposed to use of the actuator’s volume efficiency hо , characterizing the degree of tightness and operating conditions, and hydromechanical hгм efficiency of the actuator, taking into account energy losses due to hydraulic resistance in the channels and friction in it. There are given the calculated dependences for hо and hгм. The scientific novelty of the results presented in the work is that the problem of structural (static) and dynamic optimization of the design of a servo pneumatic device has been solved. A distinctive feature of the above methods for selecting the optimal parameters of a servo pneumatic device is that they are used not at the final stage of development, but at the design stage of a newly developed product, which saves money, time and costs for conducting expensive tests. This work is based and is implemented as a course of lectures of the course “Dynamics of Pneumatic drive”, is red by the author at the Bauman Moscow State Technical University at the Department of “Hydromechanics, Hydraulic Machines and Hydropneumoautomatics” (E10), as part of the preparation of masters in the specialty 05.04.13 – Hydraulic machines and hydropneumatic drives.

Neural network based autonomous control of a speech synthesis system

• Control of composite tasks by adaptive heuristically enhanced gradient approximation. • Training an artificial neural network (ANN) to control the parameters of a speech synthesizer. • The training error is estimated from the “quality” of the produced speech and not at the outputs of the ANN. • Currently used ANN training algorithms cannot cope with the above requirement. • The presented methodology may be applied to other applications too, e.g., coordination of robotic manipulators. This work is inspired by the ability of neural systems to control the behavior of specialized actuator mechanisms in living organisms by monitoring the end-effect of their actions. We consider as an example of such an actuator mechanism the human vocal tract where neurons learn to activate its muscles that move the velum, jaw, tongue and the lips, in order to exhibit desired phonetic activity. As a technical approximation to such a setup, we use an artificial neural network (ANN) and a speech synthesizer and we study the capability of the ANN to estimate the synthesizer’s parameters targeting desired speech activity. In this setup, we assume that the training error is obtained by measuring the “perceived distance” between the original (target) and the synthesized speech signals. Thus, the training error needs to be measured after processing the output of the speech synthesizer, instead of measuring it directly at the outputs of the ANN. This operational requirement on error measurement restricts the application of widely used ANN training algorithms that are based on back propagation of gradients but can be met by our earlier proposed “Heuristically Enhanced Gradient Approximation” (HEGA) algorithm. We also propose enhancements to HEGA that further optimize its performance in this demanding application.

Fuzzy-Sliding Mode Control for Humanoid Arm Robots Actuated by Pneumatic Artificial Muscles With Unidirectional Inputs, Saturations, and Dead Zones

Recently, the pneumatic artificial muscle (PAM) that can reproduce natural muscle functionalities has become one of the core actuator mechanisms of intelligent interactive soft robots. Unfortunately, some inherent defects (e.g., unignorable nonlinearities, hysteresis, low shrinkage frequencies, etc.) have limited the application progress of humanoid PAM arm robots. Additionally, the input constraints (e.g., saturations, dead zones, unidirectional inputs, etc.), unexpected external disturbances, unidentifiable system parameters, and inevitable unmodeled dynamics are usually complicated, which cannot be easily eliminated through existing adaptive control methods. This article proposes an adaptive fuzzy-sliding mode control method for humanoid PAM arm robots <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">without</i> any information of precise model structures and system parameters, which can suppress the unexpected effects of complicated unknown functions and achieve high performance tracking control, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">simultaneously</i> . To the best of our knowledge, the proposed controller is the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">first</i> method for the humanoid PAM arm robots that considers the nonlinear input constraints including unidirectional conditions, saturations, and dead zones, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">simultaneously</i> . Next, all the input constraints, system parameter uncertainties, unmodeled dynamics, and external disturbances can be estimated adaptively by utilizing the proposed fuzzy update law. Particularly, a sliding mode control law is designed to compensate possible fuzzy approximation errors, and rigorous Lyapunov-based stability analysis is provided to ensure that the state errors can converge to zero within <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">finite</i> time. Hardware experiments are carried out later tovalidate the effectiveness and robustness of the proposed method.

Control Strategies for Soft Robot Systems

Soft robots have recently attracted increased attention because their characteristics of low‐cost fabrication, durability, and deformability make them uniquely suited for applications in bio‐integrated systems. Being fundamentally different from traditional rigid robots, soft robots exhibit properties of infinite degrees of freedom (DOF) and nonlinear materials properties that require innovations in control systems. With the rapid development of materials science, robotics, and artificial intelligence, the diversification of actuator mechanisms and algorithms has enabled a wide range of unique control strategies. This review summarizes the basics of actuator mechanisms and control strategies, including open‐loop control, closed‐loop control, and autonomous control, and discusses their implementation from diversified perspectives. Control strategies are evaluated based on their compatibility with materials sets, application goals, and implementation route. The emerging directions are forecasted from the perspectives of interfacing between controller and actuator, underactuated control strategies, and implementation of artificial intelligence (AI).

Micro-plasma actuator mechanisms in interaction with fluid flow for wind energy applications: operational parameters

Micro-plasma actuator mechanisms in interaction with fluid flow for wind energy applications: operational parameters

Optimal Control in Manufacturing Areas Increase the Productivity in the Aerospace Industry of Mexicali, Baja California, México

The efficient control in the manufacturing control is very essential to increase the productivity and some specialized devices are made with and adequate functions. These devices are MEMS (Micro Electromechanical Systems), which are low-power microdevices widely used in the industrial processes of the Mexicali aerospace industry, which have the function of controlling the operation of industrial systems at any stage of manufacturing by evaluating the way to carry out their activities, comparing standardized values with data real and activate and deactivate high power actuator mechanisms such as fans, motors, electric pumps and other high power used in this installed industry. These microdevices have specific characteristics in their operation to obtain the best operational performance of industrial equipment and machines, at a low cost and partially operating according to the operating system reference values of industrial systems and generating a safe process in their operation. The industrial processes of the Mexicali aerospace industry require specialized knowledge because they manufacture components with very rigid operations because they are manufactured for aircraft with very rigorous regulations, due to the high security that air transport requires. MEMS have increased their use in the last ten years, where it has been applied to various industries due to the simple way of coupling with industrial systems, and this is why research was conducted to evaluate its use in a company in this city that they did not intend to use them and when observing that they increased their productive performance at one stage of their industrial processes, they chose to apply them in all their manufacturing areas. The investigation was from 2018 to 2019.

Optimal Control in Manufacturing Areas Increase the Productivity in the Aerospace Industry of Mexicali, Baja California, México

The efficient control in the manufacturing control is very essential to increase the productivity and some specialized devices are made with and adequate functions. These devices are MEMS (Micro Electromechanical Systems), which are low-power microdevices widely used in the industrial processes of the Mexicali aerospace industry, which have the function of controlling the operation of industrial systems at any stage of manufacturing by evaluating the way to carry out their activities, comparing standardized values with data real and activate and deactivate high power actuator mechanisms such as fans, motors, electric pumps and other high power used in this installed industry. These microdevices have specific characteristics in their operation to obtain the best operational performance of industrial equipment and machines, at a low cost and partially operating according to the operating system reference values of industrial systems and generating a safe process in their operation. The industrial processes of the Mexicali aerospace industry require specialized knowledge because they manufacture components with very rigid operations because they are manufactured for aircraft with very rigorous regulations, due to the high security that air transport requires. MEMS have increased their use in the last ten years, where it has been applied to various industries due to the simple way of coupling with industrial systems, and this is why research was conducted to evaluate its use in a company in this city that they did not intend to use them and when observing that they increased their productive performance at one stage of their industrial processes, they chose to apply them in all their manufacturing areas. The investigation was from 2018 to 2019.

A novel traveling wave piezoelectric actuated wheeled robot: design, theoretical analysis, and experimental investigation

Traditional traveling wave robots have strict requirements on the operating interface due to the fact that they usually only work on smooth and flat surfaces, holding the disadvantages of poor load capacity and complex driving mode, and limiting their application range. In order to overcome the above problems, a novel traveling wave piezoelectric actuated wheeled robot is proposed in this study. The robot is composed of a bonded-type piezoelectric actuator and wheel mechanisms. Rotating traveling wave can be produced in the annular parts of the piezoelectric actuator to drive the wheel mechanisms. In order to study the dynamic characteristics of the piezoelectric actuator, an electromechanical coupling model is developed by using the transfer matrix method. Then the prototype of the piezoelectric actuator is fabricated and assembled, and its vibration characteristics are measured to confirm the feasibility of the developed transfer matrix model. Finally, performance evaluation investigations of the proposed traveling wave piezoelectric actuated wheeled robot are conducted. Under the excitation voltages of 350 V pp and the phase difference of 90°, the robot prototype achieved a step climbing angle of 75°, a maximum no-load velocity of 136.8 mm s−1, and a maximum payload of 320 g. The proposed traveling wave piezoelectric actuated wheeled robot presents expected terrain adaptability and obstacle climbing capability.

Development of improved performance electromagnetic valve for liquid rocket engine

The problem of developing optimal-design electromagnetic valves is relevant for many industries. The development of technology is characterized by increased power and pressures used for actuator mechanisms, as well as by reducing the dimensions and mass of automatic units. The goal of this article is to develop an advanced electromagnetic valve that would ensure optimal combination of high performance, reliability, technological effectiveness and minimal cost. On the basis of standard dependences for electromagnetic phenomena a mathematic model of a SU.1 valve was developed. It was calculated in several special-purpose software packages: NISA, FEMM, ANSYS Maxwell. Parametric analysis was implemented in ANSYS Maxwell for variable working gap settings and values of current force in the solenoid. As a result, the magnetic induction distribution field was obtained. The results of modeling the operation of the electromagnetic valve and the magnetic induction distribution field are presented for variable working gap settings and different values of current force in the solenoid. The model of an advanced electromagnetic valve for a liquid rocket engine was developed on the basis of the dependences obtained. The duration of single engine firing obtained is 40 msec. The results obtained make it possible to create a valve with hold-open time of 800msec, which is considered sufficient for application in electromagnetic direct current valves.

NITINOL-based actuator for device control even in high-field MRI environment.

BackgroundThe magnetic resonance imaging (MRI) environment with its high-strength magnetic fields requires specialized and sometimes sophisticated solutions for otherwise simple problems. One of these problems is MR-compatible actuator mechanisms that transfer a signal into an action.PurposeNormal actuators are based on a magnetic effect (eg, relays) and will typically not work in magnetic fields exceeding 1000 G, eg, inside the bore of an MR scanner. To enable the use of clinical devices inside the MRI, eg, for interventional procedures, there is a need for fully compatible actuators.Patients and methodsVarious actuators were compared for the purpose as a simple on-off switch within an MRI. NITNOL wire as an actuator showed the highest potential because of its simplicity and reliability. We tested the possible force achieved by the NITINOL wire related to the respective energy consumption, to provide a travel range of 2 mm.ResultsCompared to other actuators, the NITNOL wire is cheaper and requires less space. In the switching process however, there is a delay due to the time required for the heating of the wire up to the transformation temperature. The NITINOL switch shows a reliable behavior with regard to the generated force and the switching path over the entire measurement. Significant artifacts, caused by the NITNOL wire could not be detected in the MRI.ConclusionNITINOL wires can be repeatedly used, are relatively easy to implement and could be an economic alternative to other more complicated actuator technologies.

Analysis of spacecraft actuator mechanisms design process using tensor method

There is high topicality of more and more complicated systems analysis currently. One of the means to do such analysis is to use Gabriel Kron tensor method. The process of spacecraft driving gear design is analysed by using tensor method. The problematic stages of the process are determined.

Toward steerable electrodes. An overview of concepts and current research.

Abstract Restoration of hearing is a demanding surgical task which requires the insertion of a cochlear implant electrode array into the inner ear while preserving the delicate basilar membrane inside the cochlea for an atraumatic insertion. Already shortly after the first clinical success with early versions of cochlear implants the desire for a controlled insertion of the electrode array arose. Such a steerable electrode should be in its shape adaptable to the individual path of the helical inner ear in order to avoid any contact between the implant and the surrounding tissue. This article provides a short overview of concepts and actuator mechanisms investigated in the past and present with the objective of developing a steerable electrode array for an individualized insertion process. Although none of these concepts has reached clinical implementation, there are promising experimental results indicating that insertion forces can be reduced up to 60% compared to straight and not steerable electrodes. Finally, related research topics are listed which require considerable further improvements until steerable electrodes will reach clinical applicability.

Design and testing of botanical thermotropic actuator mechanisms in thermally adaptive building coverings

This paper lays out the inspiration, operational principles, analytical modeling and coupon testing of a new class of thermally adaptive building coverings. The fundamental driving concepts for these coverings are derived from various families of thermotropic plant structures. Certain plant cellular structures like those in Mimosa pudica (Sensitive Plant), Rhododendron leaves or Albizia julibrissin (Mimosa Tree), exhibit actuation physiology which depends on changes in cellular turgor pressures to generate motion. This form of cellular action via turgor pressure manipulation is an inspiration for a new field of thermally adaptive building coverings which use various forms of cellular foam to aid or enable actuation much like plant cells are used to move leaves. When exposed to high solar loading, the structures use the inherent actuation capability of pockets of air trapped in closed cell foam as actuators to curve plates upwards and outwards. When cold, these same structures curve back towards the building forming large convex pockets of dead air to insulate the building. This paper describes basic classical laminated plate theory models comparing theory and experiment of such coupons containing closed-cell foam actuators. The study concludes with a global description of the effectiveness of this class of thermally adaptive building coverings.

Actuator Design and Flight Testing of an Active Microspoiler-Equipped Projectile

Actively controlled gun-launched projectiles require a means of modifying the projectile flight trajectory. While numerous potential mechanisms exist, microspoiler devices have been shown to be a promising control actuator for fin-stabilized projectiles in supersonic flight. These devices induce a trim force and moment generated by the boundary layer–shock interaction between the projectile body, rear stabilizing fins, and microspoilers. Previous investigations of microspoiler mechanisms have established estimates of baseline control authority, but experimental results have been restricted to cases in which the mechanism was statically deployed. This paper details the design and flight testing of a projectile equipped with a set of active microspoilers. A mechanical actuator is proposed that exhibits unique advantages in terms of robustness, simplicity, gun-launch survivability, and bandwidth compared to other projectile actuator mechanisms considered to date. A set of integrated test projectiles is constructed using this actuator design, and flight experiments are performed in which the microspoilers are oscillated near the projectile roll frequency. Data obtained from these flight tests are used in parameter estimation studies to experimentally characterize the aerodynamic effects of actively oscillating microspoilers. These predictions compare favorably with estimates obtained from computational fluid dynamics (CFD). Overall, the results presented here demonstrate that actively controlled microspoilers can generate reasonably high levels of lateral acceleration suitable for trajectory modification in many smart-weapons applications.

Grinding efficiency improvement of hydraulic cylinders parts for mining equipment

The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms. In the course of the research work methods of machine retaining devices design were used, the scientific approaches for the selection of progressive grinding schemes were applied; theoretical and practical experience in the design and production of new constructions of grinding tools was used. As a result of this work it became possible to create a progressive construction of a machine retaining device for grinding of large parts of hydraulic cylinders, to apply an effective scheme of rotary abrasive treatment, to create and implement new design of grinding tools by means of grains with controllable shape and orientation. Implementation of the results obtained in practice will improve the quality and performance of repairing and manufacturing of mining equipment.