Actuators Research Papers - Academia.edu (original) (raw)

Valve-controlled hydraulic actuation systems are favored in many applications due to their fast response, high power-to-weight ratio, and stability under variable working conditions. Efficiency, however, is the main disadvantage of these... more

Valve-controlled hydraulic actuation systems are favored in many applications due to their fast response, high power-to-weight ratio, and stability under variable working conditions. Efficiency, however, is the main disadvantage of these systems. Pump-controlled hydraulic actuations, on the other hand, eliminate energy losses in throttling valves and require less cooling. Furthermore, they inherently hold the ability to recover energy from assistive loads. Pump-controlled circuits for double-rod cylinders are well developed and are implemented in many industrial applications, including aviation. However, pump-controlled circuits for single-rod cylinders usually experience performance issues during specific modes of operation. In this paper, a new circuit using two valves to compensate for the differential flow of single-rod actuators is proposed. The compensating valves provide limited throttling over the differential flow only in critical operating regions to alleviate unwanted vel...

Integrating nano- to micro-sized dielectric fillers to elastomer matrices to form dielectric composites is one of the commonly utilized methods to improve the performance of dielectric elastomer actuators (DEAs). Barium titanate (BaTiO3)... more

Integrating nano- to micro-sized dielectric fillers to elastomer matrices to form dielectric composites is one of the commonly utilized methods to improve the performance of dielectric elastomer actuators (DEAs). Barium titanate (BaTiO3) is among the widely used ferroelectric fillers for this purpose; however, calcium copper titanate CaCu3Ti4O12 (CCTO) has the potential to outperform such conventional fillers. Despite their promising performance, CCTO-based dielectric composites for DEA application are studied to a relatively lower degree. Particularly, the composites are characterized for a comparably small particle loading range, while critical DEA properties such as breakdown strength and nonlinear elasticity are barely addressed in the literature. Thus, in this study, CCTO was paired with polydimethylsiloxane (CH3)3SiO[Si(CH3)2O]nSi(CH3)3 (PDMS), Sylgard 184, to gain a comprehensive understanding of the effects of particle loading and size on the dielectric composite properties ...

Improving the functional stability of shape memory alloys (SMAs), which undergo a reversible martensitic transformation, is critical for their applications and remains a central research theme driving advances in shape memory technology.... more

Improving the functional stability of shape memory alloys (SMAs), which undergo a reversible martensitic transformation, is critical for their applications and remains a central research theme driving advances in shape memory technology. By using a thin-film composition-spread technique and high-throughput characterization methods, the lattice parameters of quaternary Ti–Ni–Cu–Pd SMAs and the thermal hysteresis are tailored. Novel alloys with near-zero thermal hysteresis, as predicted by the geometric non-linear theory of martensite, are identified. The thin-film results are successfully transferred to bulk materials and near-zero thermal hysteresis is observed for the phase transformation in bulk alloys using the temperature-dependent alternating current potential drop method. A universal behavior of hysteresis versus the middle eigenvalue of the transformation stretch matrix is observed for different alloy systems. Furthermore, significantly improved functional stability, investigated by thermal cycling using differential scanning calorimetry, is found for the quaternary bulk alloy Ti50.2Ni34.4Cu12.3Pd3.1.

We propose a dynamics model of galvanotaxis (locomotor response to electrical stimulus) of the protozoan Paramecium. Our purpose is to utilize microorganisms as micro- robots by using galvanotaxis. For precise and advanced actuation, it... more

We propose a dynamics model of galvanotaxis (locomotor response to electrical stimulus) of the protozoan Paramecium. Our purpose is to utilize microorganisms as micro- robots by using galvanotaxis. For precise and advanced actuation, it is necessary to describe the dynamics of galvanotaxis in a mathematical and quantitative manner in the framework of robotics. However, until now the explanation of Paramecium galvanotaxis in previous works has remained only qualitative. In this paper, we construct a novel model of galvanotaxis as a minimal step to utilizing Paramecium cells as micro-robots. Numerical experiments for our model demonstrate realistic behaviors, such as U-turn motions, like those of real cells. Index Terms—Paramecium, galvanotaxis, dynamics, model, microrobot

Due to pursuance along expand within measure accidents the death sum is increasing but it is a main subject than absolute can’t imaging. The rationale for street accidents are the driver’s potation consumption. The death dimension... more

Due to pursuance along expand within measure accidents the death sum is increasing but it is a main subject than absolute can’t imaging. The rationale for street accidents are the driver’s potation consumption. The death dimension excellent according to bust and pressure is in excessive amongst rate splendid of conformity over such especially among nations as like India. So a dictation is proposed in conformity with become aware of the alcohol content fabric board atop the driver. The proposed job explores the possibility in conformity with discover wine at without a doubt previous utilizes concerning technology. The leader can't start the vehicle circumstance the potation content material cloth is upstairs the outset value. The delivered purposes in imitation about that regulation is the alcohol sensors trip solely the individual insertion within the driver’s foundation afterward desire no longer soak up into estimate touching the equalize passenger. It is additionally lower back in imitation including music the rebate regarding the automobile postulate into so much location the use on the mum or dad mark attention technique. This is done with the aid about measures of the sensors related in imitation of the Node MCU Arduino micro khan the region so much is programmed in consequence along assign a buzzer answer consequently the leader is below the affect concerning wine yet switch among pursuance along the vehicle.

Smart Materials are also known as advanced materials or intelligent materials or responsive materials. These materials can be defined as advanced materials that can respond smartly to environmental changes. The general feature of all... more

Smart Materials are also known as advanced materials or intelligent materials or responsive materials. These materials can be defined as advanced materials that can respond smartly to environmental changes. The general feature of all smart materials is the fact that one or more properties might be significantly altered under controlled conditions by external stimuli such as stress, moisture, electric fields, magnetic fields, light, temperature etc.. This study focuses on Smart Materials types and applications in various fields.

The present work concentrate on the study of the components of the excavator in order to identify the problems faced while performing the lifting and digging operations and to provide a design solution by using CAD-CAE systems.For light... more

The present work concentrate on the study of the components of the excavator in
order to identify the problems faced while performing the lifting and digging operations and
to provide a design solution by using CAD-CAE systems.For light duty construction work,
generally mini hydraulic backhoe excavators are used and mostly there are soil surfaces for
excavation. So, design of backhoe excavator is critical task in context of digging force
developed through actuators during the digging operation. The important criteria for the
design to be safe is that, the digging forces developed by actuators must be greater than that of the resistive forces offered by the surface to be excavated. The two important factors considered during designing an excavator arm are productivity and fuel consumption. As the present mechanism used in excavator arm is subjected to torsional and bending stresses during lifting and digging operation respectively, because of which failure occurs frequently at the bucket end of the arm. So, the new mechanism of excavator arm is designed and the Pro-e software is used for making the 3D model of the excavator arm linkage. By using ANSYS workbench software static analysis of each of the excavator arm component is done at existing digging force and also at newly calculated digging force. Also the bucket volume is increased to compensate for the loss in production due to the reduction in digging force.

A state-feedback controller was designed to simulate the Starling response of the heart in a mock circulatory system (MCS). The controller drives a voice coil actuator (VCA) to follow a reference volume, and thus generate the desired... more

A state-feedback controller was designed to simulate the Starling response of the heart in a mock circulatory system (MCS). The controller drives a voice coil actuator (VCA) to follow a reference volume, and thus generate the desired chamber pressure, by using position and speed feedbacks. The reference volume was adjusted according to the maximum ventricular elastance (Emax), end-systolic ventricular pressure, and left atrial pressure to respond to load variation in the MCS. The controller was tested in computer simulation by changing the load conditions and Emax of the MCS. The MCS along with the controller was able to reproduce human heart function from healthy to sick conditions. A rotary ventricular assist device (VAD) was then introduced in the simulation to test the MCS. The MCS was able to produce a consistent cardiac function even with the presence of the VAD. These results suggest that the new MCS control system is able to simulate the cardiac function for VAD test.

A wearable robot with linear actuators is required to maintain over the desired payload over whole range of knee joint angle even when the user is walking, sitting down/standing up while holding up weights. However, in knee-flexion... more

A wearable robot with linear actuators is required to maintain over the desired payload over whole range of knee joint angle even when the user is walking, sitting down/standing up while holding up weights. However, in knee-flexion posture, the lifting payload at the knee joint decreases drastically by the moment arm of linear actuators and the cosine of joint angle. In order to solve the problem of the payload decrease, the sub-links attaching on actuators and the sub-link with shank bending method are proposed. As the result, two methods are successfully proved to increase the payload by simulation.

Pump-controlled hydraulic circuits offer an energy-efficient solution for many applications. They combine the high power to weight ratio of hydraulic technology with the ease of control of electric technology. Pump-controlled circuits for... more

Pump-controlled hydraulic circuits offer an energy-efficient solution for many applications. They combine the high power to weight ratio of hydraulic technology with the ease of control of electric technology. Pump-controlled circuits for double-rod cylinders are well developed as compared to those of single-rod cylinders. In spite of many initiatives, certain common pump-controlled single-rod cylinder solutions present stability issues during specific modes of operation. Common examples of the solutions are circuits that utilize pilot-operated check valves and circuits that use shuttle valves. In these circuits, velocity oscillations have been reported during actuator retraction at low assistive loads. In this paper, we study the area on the load-velocity graph of the available circuits where oscillatory behavior is experienced. We then propose a solution that shifts this critical zone towards lower loading values. This in turn reduces system response oscillations. Shifting the cri...

Microelectromechanical (MEM) Accelerometers measure the accelerations or vibrations experienced by objects due to inertial forces or mechanical excitations. To improve their proof mass displacement, several alternatives have been used,... more

Microelectromechanical (MEM) Accelerometers measure the accelerations or vibrations experienced by objects due to inertial forces or mechanical excitations. To improve their proof mass displacement, several alternatives have been used, such as the design of different shapes of suspension beams. In this work, a new shape of beam is proposed based on alternated segments of different widths. To analyze its performance, one-quarter, middle and complete accelerometers were calculated and simulated; the results were compared with similar cases using conventional uniform-shaped beams. A notable improvement in the proof mass displacement was obtained in all cases, especially with the proposed symmetrical-shaped beam. Harmonic response and explicit dynamic analysis were also considered to discover performance when they are subjected to structural load. An improvement in amplitude displacement was also observed, as well as operation frequency reduction. From the explicit dynamic analysis, a f...

The hyper-automaton is introduced as a model of complex control algorithms. The model reflects basic aspects of control algorithms: presence of an external environment, cyclic and event-driven functioning, synchronism, hierarchical... more

The hyper-automaton is introduced as a model of complex control algorithms. The model reflects basic aspects of control algorithms: presence of an external environment, cyclic and event-driven functioning, synchronism, hierarchical structure and logical parallelism. The paper introduces basic definitions and conceptual means of hyper-automaton model, which encourage program implementation of the algorithms. A new kind of functional polymorphism we name event- driven polymorphism is distinguished and discussed.

The stiffness of an actuator depends on the closed-loop position control (architecture and parameters), on the load frequency, and, for fault-tolerant actuators, on the operative mode. The stiffness response is of basic importance for the... more

The stiffness of an actuator depends on the closed-loop position control (architecture and parameters), on the load frequency, and, for fault-tolerant actuators, on the operative mode. The stiffness response is of basic importance for the design of actuators for primary flight controls, especially for high-performance aircrafts. Actually, in-flight conditions characterized by high speed and high angle-of-attack, the dynamic interactions between aircraft structure, actuator, and aerodynamic loads can induce aeroservoelastic effects, which, if not controlled, can imply performance degradation and even instability. The study and the compensation of such concerns require the assessment of the resonant frequencies of the aeroservoelastic system, which can be performed only by characterizing the dynamic stiffness of the actuator. This article reports the experimental activities carried out for the characterization of the stiffness response of a fault-tolerant fly-by-wire actuator for the primary flight controls of a modern jet trainer, starting from the feasibility studies of the experiments up to the execution of the vibration tests. The actuator stiffness performance is evaluated in different fail-operative modes by artificially injecting hydraulic and electrical failures, and the experimental data are interpreted by means of an LTI model of the flight actuator, highlighting and discussing the effects that the failures induce on the stiffness performance.

ABSTRACT Application of a fuzzy logic controller to a class of hydraulically actuated industrial robots is investigated. A simple set of membership functions and rules are described which meets certain control requirements. An off-line... more

ABSTRACT Application of a fuzzy logic controller to a class of hydraulically actuated industrial robots is investigated. A simple set of membership functions and rules are described which meets certain control requirements. An off-line routine based on the simplex method is outlined to tune the controller gains for an optimum response. The fuzzy control gains are tuned by minimizing the summation of absolute position errors over step input responses. The fuzzy logic controller is first examined through simulation of a two-link hydraulic robot of the same hydraulic configuration as many industrial manipulators. The controller has positive aspects which cannot be easily achieved by conventional control techniques. These include a fast rise-time and a well maintained damped response. The fuzzy controller is applied to an instrumented Unimate MK-II industrial hydraulic robot. The experimental results are encouraging in that the best performing control gains are found for different links with a reasonable number of trials and produce step responses with fast response and few oscillations at the set point. The controller demonstrates robustness

Continuous-facesheet and segmented Boston Micromachines Corporations' (BMC) Micro-Electrical Mechanical Systems (MEMS) Deformable Mirrors (DM) have been tested for their response to high-power visible-wavelength laser light. The... more

Continuous-facesheet and segmented Boston Micromachines Corporations' (BMC) Micro-Electrical Mechanical Systems (MEMS) Deformable Mirrors (DM) have been tested for their response to high-power visible-wavelength laser light. The deformable mirrors, coated with either protected silver or bare aluminum, were subjected to a maximum of 2 Watt laser-light at a wavelength of 532 nanometers. The laser light was incident on a ~ 3.5×3.5 cm area for time periods from minutes to 7 continuous hours. Spot heating from the laser-light is measured to induce a local bulge in the surface of each DM. For the aluminum-coated continuous facesheet DM, the induced spot heating changes the surface figure by 16 nm rms. The silver-coated continuous-facesheet and segmented (spatial light modulator) DMs experience a 6 and 8 nm surface rms change in surface quality with the laser at 2 Watts. For spatial frequencies less than the actuator spacing (300 mm), the laser induced surface bulge is shown to be rem...

ABSTRACT Ultrasonically Assisted Machining (UAM) is an emerging technology that has proven to be very efficient in improving the surface finishing in material machining such as turning, milling, and drilling. Smart material actuators are... more

ABSTRACT Ultrasonically Assisted Machining (UAM) is an emerging technology that has proven to be very efficient in improving the surface finishing in material machining such as turning, milling, and drilling. Smart material actuators are used in such applications to vibrate the cutting tip while machining, hence, improving the manipulated surface. In order to achieve that, it is required to vibrate the cutting tip at certain frequency with certain amplitude. In fact, controlling the amplitude of these smart actuators is a tedious and difficult task due to the inherent nonlinearities associated with smart materials. In this paper, two control algorithms are proposed; sliding mode controller with high frequency (SMHF) and proportional-integral controller with RMS (PIRMS). Numerical simulations are presented to demonstrate the effectiveness of using the proposed controller. The PIRMS algorithm demonstrates a better performance when compared with the SMHF algorithm.

The current paper deals with the study of the electrical failures in fault-tolerant flight actuators, with particular reference to the short circuits of the servovalve coils. A highfidelity model of the servovalve of a modern fly-by-wire... more

The current paper deals with the study of the electrical failures in fault-tolerant flight actuators, with particular reference to the short circuits of the servovalve coils. A highfidelity model of the servovalve of a modern fly-by-wire actuator is developed and validated through experiments, focusing attention on the characterization of the component dynamics in case of partial and total short circuits of the direct-drive motor coils. The servovalve model is then used to simulate a typical on-ground built-in-test procedure to determine the limit condition for the detection of a partial short circuit. Finally, once different possible combinations of short circuits are injected, the degradation of performances of the whole actuator is characterized through experiments, and the servovalve model is used to justify the test results, highlighting and discussing the effects of the failures on the system dynamics.