Cost Effective Actuator Research Articles

Thermal and fatigue endurance strain response in low temperature sintered 0.4PZN-0.6PZT ceramics for actuator applications

Piezo-ceramics with low sintering temperature (<1000 °C), enhanced strain (>0.1 %), low degree of hysteresis (<10 %), fatigue resistance (>106 cycles) with better thermal stability are extremely important characteristics for the development of high performance and cost-effective actuators. In this study, temperature (−50 to 250 °C) and fatigue (100 to 106) dependence of ferro/piezoelectric (P-E/S-E) characteristics of low temperature sintered (950 °C) (0.4[Pb(Zn1/3Nb2/3)O3-0.6Pb(Zr0.49Ti0.51)O3]) ceramics was investigated. A thermally stable strain response with a maximum of 0.17 % and degree of strain hysteresis (ηhys) of < 10 % was observed till 250 °C. The fatigue studies revealed a robust unipolar strain stability till 106 cycles even up to 200 °C. Interestingly, a very minimal strain asymmetry (γS) was observed only after 104 cycles till 200 °C, unlike PZT-5A, PIC151 and PMN-PT. This study demonstrates an exceptional thermal and fatigue resistant strain response even close to the Curie transition temperature (TC ∼ 280 °C) and suggests that the low temperature sintered 0.4PZN-0.6PZT ceramics could be a promising material, exclusively for high-precision actuator applications over a wide temperature range with a cost-effective solution.

Synchronous Control of 2-D.O.F Master-Slave Manipulators Using Actuators With Asymmetric Nonlinear Dead-Zone Characteristics

Although the various synchronous control techniques of a master-slave manipulator have been explored and developed over the decades, the investigations of the synchronous control for those systems with strong asymmetric dead-zone characteristics have been limited and not been fully considered. Hence, we proposed the robust and easy-to-implement estimation and control strategy to compensate for the actuator’s dead-zone effect and to guarantee synchronous performance. Specifically, we set up a two-step process called prior-estimation control to avoid the performance degradation due to the frequent failures of the desired estimation in a standard adaptive control. The first step is to adaptively estimate the asymmetric nonlinear dead-zone parameters via the Recursive Least Square (RLS) method. At the second stage, those estimated parameters via RLS are delivered to the main synchronous control system designed by a passivity-based sliding mode control technique along with inverse dead-zone control, and then the control is executed whenever a human operator interacts with the system. Finally, the effectiveness of the proposed approach has been validated by the actual 2-D.O.F master-slave manipulators equipped with cost-effective actuators with an inevitable asymmetric dead-zone. This work will be especially a valuable asset for those who wish to accurately control the master-slave systems with dead-zone characteristics such as the industrial construction multiple joints based fork cranes or lifts.

Conceptual Design of a Low - Cost Linear Actuator for Variable Span Wing Application

Aerospace actuators can be found throughout modern commercial and experimental aircraft, as well as in military and space exploration. The aerospace industry is not only growing, but also rapidly changing and the demand for aerospace actuators is permanently increasing. Linear actuator is able to push, pull, and hold objects in a way that our bodies cannot. Additionally, electrically powered technology provides more sophisticated control options. Linear actuator drive many different functions that are essential to safe and efficient aircraft operation. Manufacturers and hobbyists alike are always on the hunt for new ways to automate functions while keeping development costs low. Providing cost-effective linear solutions for aerospace application is one of the biggest challenge. This research will provide a cost-effective actuator conceptual design for variable span morphing wing UAV. The cost-effective design will be presented along with the application-based selection of linear actuators for morphing wing UAV.

Quantifying acoustic damping using flame chemiluminescence

Thermoacoustic instabilities in gas turbines and aeroengine combustors fall within the category of complex systems. They can be described phenomenologically using nonlinear stochastic differential equations, which constitute the grounds for output-only model-based system identification. It has been shown recently that one can extract the governing parameters of the instabilities, namely the linear growth rate and the nonlinear component of the thermoacoustic feedback, using dynamic pressure time series only. This is highly relevant for practical systems, which cannot be actively controlled due to a lack of cost-effective actuators. The thermoacoustic stability is given by the linear growth rate, which results from the combination of the acoustic damping and the coherent feedback from the flame. In this paper, it is shown that it is possible to quantify the acoustic damping of the system, and thus to separate its contribution to the linear growth rate from the one of the flame. This is achieved by postprocessing in a simple way simultaneously acquired chemiluminescence and acoustic pressure data. It provides an additional approach to further unravel from observed time series the key mechanisms governing the system dynamics. This straightforward method is illustrated here using experimental data from a combustion chamber operated at several linearly stable and unstable operating conditions.

A flat and cost effective actuator based on superabsorbent polymer driving a skin attachable drug delivery system

We present a flat and cost effective volume displacement actuator based on superabsorbent polymer. It offers slow kinetics and is able to work against reasonable back-pressures, e.g. 0.50 ml in 235 min at 140 kPa. It is predestined for low-cost skin attachable drug delivery devices. The actuator consists of a plastic ring filled with superabsorbent polymer granulate. It is sealed with a thermoplastic elastomeric membrane on one side and a stiff filter membrane on the other side. After adding a defined amount (e.g. 2 or 10 ml) of swelling agent the actuator shows a fast initial volume displacement within a few minutes followed by a slow continuous increase of this volume within hours. Minimized initial volume displacement and maximized displaced volume after 4 h cannot be combined in one actuator. A minimized initial displacement can be as low as 0.10 ml± 0.03 ml. A maximized displaced volume after 4 h can be 1.71 ml± 0.18 ml, not considering the initial effect. The back-pressure dependency of one selected actuator design was studied. At a back-pressure of 100 kPa the displaced volume is reduced by 33%. We investigated various actuator designs with varying surface area, hardness of the elastomeric membrane and superabsorbent polymer. Finally, we demonstrate a skin attachable drug delivery system based on the employment of the superabsorbent polymer actuator.

Design of a magnetostrictive (MS) actuator

Several advanced technologies are introduced in automotive applications. Higher energy density and dynamic performance are demanding new and cost-effective actuator structures. Magnetostriction (MS), change in shape of materials under the influence of an external magnetic field, is one of the advanced technologies. Good understanding of specific design constrains is required to define and optimize a magnetostrictive actuator. This paper presents parametrical analysis with magnetic simulation of a magnetostrictive actuator. Proposed actuator has been designed, and the performance has been evaluated on experimental rig. Strain, elongation of the shaft, of 1000 ppm at 10 A and a blocked force over 4500 N has been achieved with shaft of 8 mm diameter, made of Terfenol- D. Furthermore, the effect of pre-stress of the Terfenol- D shaft has been evaluated experimentally. The study shows that excellent features can be obtained by magnetostrictive materials for many advanced applications.

An Overview about Active Oscillation Damping of Mobile Machine Structure

One main current demand for mobile machinery development is the improvement of operator comfort and productivity in order to be competitive on the global market in the future. Actual trends towards cost effective actuator systems in offroad vehicles and thereby the use of electrohydraulic actuators reflects also the task of active oscillation damping of the machine structure. In the past several concepts, which differ in hydraulic system, control and sensor strategy, have been developed. However, the practical use is still minor as in most cases passive oscillation systems, which base upon high pressure hydro-pneumatic accumulators, are widely used although the component costs and frequent check intervals are problematic for this technology. This paper presents an overview of research work done in the area of active oscillation damping technologies for offroad vehicles.