Linear Electromechanical Actuator Research Articles

Robust decomposed system control for an electro‐mechanical linear actuator mechanism under input constraints

AbstractThis paper aims to develop a robust decomposed system control (RDSC) strategy under input constraints for an electro‐mechanical linear actuator (EMLA) facing model uncertainty and external disturbances. At first, a state‐space model of a complex multi‐stage gearbox EMLA system, driven by a permanent magnet synchronous motor (PMSM), is developed, and the non‐ideal characteristics of the ball screw are presented through the model. The result is a four‐order nonlinear strict‐feedback form (NSFF) system decomposed into three subsystems. As the paper's main result, a novel RDSC strategy with uniform exponential stability for controlling subsystem states is presented. This developed controller avoids the "explosion of complexity" problem associated with backstepping by treating the time derivative of the virtual control input as an uncertain system term. The proposed method, despite assuming load disturbances and input constraints with arbitrary bounds, offers a straightforward control approach for a broader range of applications. Further, the controller's performance is evaluated by simulating two distinct duty cycles, each representing different levels of demand on the actuator facing load disturbances near the rated motor performance.

Novi dizajn pametne proteze kolenskog zgloba za osobe sa amputacijom iznad kolena

Amputees suffer greatly from lower limb amputation. A novel smart knee joint prosthesis was constructed in this research to allow the amputee to achieve regular daily movement, such as walking, standing, and ascending/descending stairs. This prosthesis employs sensors, actuators, and a mechanical system to replicate the functioning of a natural limb. As a result of the unique mechanical and electrical components employed herein to boost performance, metabolic energy is lowered. Here, a ball screw is employed, which has been determined to be the most efficient means of achieving linear motion; its precision and efficiency range from 90% to 100%. It is quieter and more efficient than a hydraulic or pneumatic system. An electromechanical linear actuator (servo cylinder) is used with an actuator control system and integrated Phase Index - Field-Oriented Control. It maintains and self-calibrates the needed position with high precision when power or backup power is unavailable. The angle of flexion achieved in this design is 120º. The gait analysis revealed that the current prosthesis could imitate the biomechanics of the normal joint with no difficulty at varied speeds when tested on an amputee (110 kg). Furthermore, it may function efficiently as a passive when power is unavailable, including the capacity to move smoothly throughout the swing phase (high accuracy through deceleration and acceleration). The current active knee joint is lightweight (2869 grams), and the cost has been greatly reduced.

An Interval Approach for Robust Parameterization of Controllers for Electric Drives

Uncertain models, e.g., due to component variations and measurement errors during system identification, in combination with the desire to be able to provide guarantees regarding system performances a priori, represent major challenges for users when designing controllers on the basis of models. The aim of this publication is to mitigate this obstacle in the design. For this purpose, criteria of classical control engineering are combined with interval arithmetic in general and the SIVIA algorithm in particular. Thereby, the approach is valid for linear dead time systems. The algorithm evaluates performance criteria for closed interval-bounded sets of parameter values in a single iteration. When overestimation prevents a definite result, the size of the parameter set is recursively reduced by bisecting the evaluated set. The application of the methodology to the controller design for an electromechanical linear actuator shows that the approach not only contributes to theory but can also simplify the practical controller design, especially in the area of electric drives.

Intelligent Self-levelling Platform for Missile Articulation

This study aims to design a self-levelling platform loaded with a missile that is articulated from 0° to 90°. The platform is not situated rigidly on the ground, but it is placed on a railway track. This creates an unbalanced condition for the platform during the missile articulation because the railway guides are not rigid and act as springs. Consequently, the objective of study was to keep the platform in a steady condition at a particular plane at all times, irrespective of the change in load with respect to position and time. A prototype was designed on CATIA V5 software and tested by using Arduino IDE which replicates the original system on a small scale. The effect of railway track was created by using springs of various stiffness coefficients. The model was manufactured and the balancing of the platform was done using linear actuators coupled with an electronic control system with a feedback mechanism. The accelerometer was used to sense the angular variation in X and Y axes along the reference plane. The electro-mechanical linear actuators were used to nullify the unbalance and hence the levelling was achieved. The various tests were performed on the prototype with variable ground conditions using different combinations of springs to validate the balancing principle. It reveals that the levelling was successful with all combinations for any unbalanced ground condition.

Modelling of Pedals Pressing Mechanisms for Low Speed Driving in Road Traffic Delay

Road traffic delay is imminent in big cities around the world including Kuala Lumpur, due to the increase in vehicle ownership, weather condition, road blocks by authorities and ongoing infrastructure projects at particular point of the road. Previous literature shows that the average time spent by drivers in driving under road traffic delay is about 30-53 minutes per day. Within the delay, regular pressings of the brake and accelerator may lead to leg and body fatigue, hence may give detrimental effect on the driver in the long run. This paper aims to mimic the pedal pressing and releasing mechanism in replacing the leg activities during road traffic delay, such that the driver will no longer need to recurrently pressing both pedals, thus reduce the fatigue. In replicating the pressing mechanism, a linear electromechanical actuator is designed for this purpose due to its high force density as well as good response time. The mathematical model of the actuator is first developed and integrated with car dynamic model in Simscape model. All parameters used for simulation purposes were taken from an actual electromechanical actuator used for the similar application. Simulation performance evaluation was conducted on a virtual environment for the integrated models and the response of the models were investigated. As a result, the actuator model is capable to produce the desired output force that is similar with human leg during pressing activity, with about 200 N force. The model was coupled with tuned PID controller, and the actuator was also able to produce an acceptable time response, where the vehicle is brought to a complete stop within less than 1 second, which is closed to the actual driver’s leg activities during the pedal pressing in a road traffic delay.

Structural Health Monitoring of Electromechanical Actuators in Aviation—Challenges Ahead and Case Study

Abstract Electrical actuation concept fits perfectly with the worldwide strategy of more electric aircraft to reduce carbon footprint. However, the integration of linear electro-mechanical actuators is promising yet challenging in safety critical systems due to the jamming of the driven load. That fault is a critical mechanical transmission failure giving rise to concern in many applications such as primary flight controls or landing gears extension and steering. This article critically reviews electric actuation solutions currently available for aerospace application, the limits for their upcoming deployment and the different solutions to achieve an on-condition maintenance to reduce any safety risk during lifetime. A particular attention is given to the jamming and possible strategies to avoid any hazard induced by this failure. The most promising approach relies on the establishment of a predictive maintenance by monitoring continuously the actuator to timely warn any structural alteration, which is prone to induce jamming. Finally, a case study is presented, showing the ability of engine current monitoring to warn any alteration in the load maneuvering. The current spectrum analysis is found to be sensitive to both mechanical fault and control failure or malfunctioning. On top of that, no addition sensors are needed, making this technique affordable and cost-effective.

Sustainable Hyperautomation in High-Tech Manufacturing Industries: A Case of Linear Electromechanical Actuators

Hyperautomation is a promising but sparingly implemented concept in intelligent manufacturing. One of the reasons for the suboptimal adoption of hyperautomation is the large gap between current theoretical frameworks and practical methodologies and tools that can be applied in a real industrial production scenario. This situation has become much more complicated in high-tech enterprises, which face a particular set of issues in terms of innovation, cost-effectiveness, and supply chain management in today’s globalized environment. This manuscript provides a new conceptual business framework and technological background for achieving sustainable hyperautomation in the manufacturing of linear electromechanical actuators (LEMA), a key component of several cyberphysical actuators. A set of digital tools and innovative concepts, such as intra-enterprise 3-level factory and definitive designs based on unified solutions, which enable mass customization and offer up to 1000 variants of the LEMAs, are introduced to achieve synergistic interaction between different business functions and provide significant cost and technological advantages. To make manufacturing more customizable, a modular design approach is used, and simultaneously, to facilitate mass production, the focus is given on roller screw transmission modules, representing approximately three-fourths of the added value of LEMA. Furthermore, the concept of synergetic forward integration is proposed and explained using an example of robotic resistance spot welding. This framework involves a closed loop of industrial mature digital tools that enables autonomous product design and manufacturing via Responsive R&D (Research and Development) and feedback-driven dynamic interactions with the marked and production system. These steps allow intelligent and automatic decision making throughout the digitally connected systems within the company and out of the company through a digital networked connected intra-enterprise world inside the supply chain with minimal human intervention.

Diagnostics of actuation system by Hadamard product of integrated motor current residuals applied to electro-mechanical actuators

The paper presents diagnostics methodology that can identify the event of occurrence of fault in the actuator or the linkage system of the flight control actuation system driven by Linear Electromechanical Actuators (LEMA). The standard data analysis like motor current signature analysis (MCSA) is good at identifying the incipient faults within the elements of the actuators in situations where-in the actuators are driving control surfaces. But in back driven cases, where-in LEMA is driven back by control surfaces, the faults outside the LEMAs are difficult to be detected due to higher mechanical advantages of transmission elements like roller screws, gear train and linkage arms scaling down their effects before reaching the motor. One such event occurred in a ground test, wherein the jet vanes were sheared when back driven by excessive gas dynamic forces. Neither the motor current nor the LEMA position feedback data has any clue of the instance of occurrence of such shearing. The case study is discussed in detail and diagnostics solution for such failures is proposed. A new methodology to pin point the event of occurrence is arrived at based on ground static test data of four independent channels. The same is reassured for its applicability using lab experiments on three samples mimicking the failure. The method's applicability is also extended for extracting events in actual flight, by comparing the flight telemetry data with the mimicked lab level (dry runs) data. The methodology uses the analysis of LEMA motor current data to arrive at the vital diagnostic information. The current data of LEMA directly cannot be interpreted due to non-stationary nature arising from variable speed and its pulsating form because of the pulse width modulation (PWM) switching, threshold voltages and closed loop dynamics of the servo. Hence the motor current is integrated using cumulative trapezoidal method. This integrated data is spline curve fitted to arrive at residuals vector. The Hadamard product is used on the residuals vector to amplify the information and suppress the noise. Further, normalizing is done to compare data across tests and samples. With this, necessary diagnostic information was extracted from static test data. The method is extended for extracting diagnostics information from actual flight using comparison analysis of, the test data in actual environment with mimicked lab level dry runs. It is also verified for applicability in faults directly driven by actuators in lab level experiments on three samples.

Design of linear electromechanical actuator for automatic ambulatory Duodopa pump

This paper focuses on the design of a linear electromechanical actuator (EMA) to be used in conjunction with a positive displacement piston-type drug dispensing syringe pump. The motivation behind this work is the development of an automated ambulatory Duodopa pump, which necessitates the design of an EMA to safeguard Parkinson's disease (PD) patients from bradykinesia and dyskinesia problems that occur due to the inability of traditional Duodopa pump in optimal drug delivery. The proposed EMA consists of a lead screw mechanism driven by a DC servo motor coupled with gears. The lead screw is designed in such a way that the rule of thumb and self-locking property are obeyed to avoid the back-driving phenomenon. The overall performance of the proposed EMA is evaluated by in-silico studies, which results in better dynamic response, stability, and reliability. The in-silico analysis of various electrical, as well as mechanical faults that are prone to happen in EMA, is also discussed in this paper. The stability of the proposed system is analyzed via frequency response plots under different load inertia values and system time delays. From the stability analysis, it is perceived that an excessive inertia mismatch or time delay may lead to instability issues in the system, even though stability is guaranteed at present. The proposed methodology emphasizes a crucial condition in the DC motor sizing that the optimum operation requires an inertia ratio as close to 1:1 as possible.

Theory and Implementation of Coupled Port-Hamiltonian Continuum and Lumped Parameter Models

A continuous Galerkin finite element method that allows mixed boundary conditions without the need for Lagrange multipliers or user-defined parameters is developed. A mixed coupling of Lagrange and Raviart-Thomas basis functions are used. The method is proven to have a Hamiltonian-conserving spatial discretisation and a symplectic time discretisation. The energy residual is therefore guaranteed to be bounded for general problems and exactly conserved for linear problems. The linear 2D wave equation is discretised and modelled by making use of a port-Hamiltonian framework. This model is verified against an analytic solution and shown to have standard order of convergence for the temporal and spatial discretisation. The error growth over time is shown to grow linearly for this symplectic method, which agrees with theoretical results. A modal analysis is performed which verifies that the eigenvalues of the model accurately converge to the exact eigenvalues, as the mesh is refined. The port-Hamiltonian framework allows boundary coupling with bond-graph or, more generally, lumped parameter models, therefore unifying the two fields of lumped parameter modelling and continuum modelling of Hamiltonian systems. The wave domain discretisation is shown to be equivalent to a coupling of canonical port-Hamiltonian forms. This feature allows the model to have mixed boundary conditions as well as to have mixed causality interconnections with other port-Hamiltonian models. A model of the 2D wave equation is coupled, in a monolithic manner, with a lumped parameter model of an electromechanical linear actuator. The combined model is also verified to conserve energy exactly.

Modeling and Simulation of Feedback based Linear Electromechanical actuator

An actuator is a device that which provides control over certain automation systems and also provides tuning in movement or positioning in various applications like manufacture of valves, motor, wastewater treatment plants, onboard electronics based on the type of configuration of type of actuators. Out of the available types of actuators, linear Electro Mechanical Actuators (EMA) is a powerful and advanced tool which provides optimal solution for the field of automation, various applications where high speed, high precision with control are required. This paper proposes to have velocity feedback system to entire function of EMA’s in order to improve its functionality, and thus enhances the efficiency. This paper also proposes modeling and simulation of normal conventional linear Electro Mechanical Actuator and velocity feedback controlled EMA and compares the results in MATLAB/SIMULINK.

Autonomous transmission control of a 2017 Yamaha Grizzly 700 all-terrain vehicle

Investigation on a designed and modified standard automatic transmission for a 2017 Yamaha Grizzly All-Terrain Vehicle was carried out to allow it to be controlled remotely and autonomously while maintaining its ability to be manually operated. The vehicle is a part of a project named AutoWeed. This project aims at developing a vehicle which can be used in the Australian outback to control and eradicate weeds. Preliminary tests were conducted on the vehicle to determine the performance parameters required to replace the movement supplied by the operator. Several devices used to achieve this motion were explored. It was concluded that the Motion Dynamics HB-DJ806 - LALI10010 electromechanical linear actuator be used as a proof of concept device for this application. This device is capable of exerting 200 N at 35 mm/seconds. It has a stroke length of 50 mm and was powered by a 12V DC motor, which drew 3 amps at maximum load. Through testing, it was found that the selected actuator did not have enough stroke length to cycle through the five gears on the ATV. This error was rectified allowing the system to function as intended. To achieve a reliable design, however, the Linak LA14 actuator was purchased as a final design as it was stronger, faster and had feedback capabilities. Before procurement, the new actuator was digitally modelled using SolidWorks 2017 and 3D printed to confirm the mounting position and method. An ANSYS FEA was conducted on all the custom-made components including the actuator bracket and mounting plate to ensure reliability. The bracket model was manufactured using 3D printing from ABS. It was recommended that for reliability, the bracket should be constructed from a stronger material such as aluminium. The results gained from testing proved that the autonomous transmission system implemented was reliable and repeatable. This was justified as the system achieved a 100% success rate when cycling through gears.

Real-Time Hybrid Testing of Strut-Braced Wing Under Aerodynamic Loading Using an Electrodynamic Actuator

Real-Time Hybrid Simulation (RTHS) is an experimental framework that allows the testing of components or substructures under realistic, dynamic boundary conditions, by imposing the reactions calculated from a model of the rest of the assembly through one or more actuators. In the context of rapid prototyping of mechanical components, RTHS could be used to explore the design space of a device while at the same time physically validating its interaction with other components of the final assembly from the early stages of the design-to-production cycle. In this work, RTHS was applied for the first time to the investigation of aerodynamic gust loading alleviation devices in a highly flexible strut-braced wing. The model wing was taken as the physical substructure and tested in a low-speed wind tunnel equipped with gust generators. The load alleviation device was simulated through a real-time feedforward-feedback controller, and its response imposed via an electro-mechanical linear actuator, in contrast with the hydraulic actuators more commonly used in standard RTHS. The controller-actuator subsystem was studied in detail to assess and minimise errors at the physical interface with the wing. The behaviour of the electromechanical subsystem showed a strong dependence on the characteristics of the numerical substructure and the frequency of excitation, and resulted in a significant discrepancy between the simulated and real displacements at the interface between the actuator and the wing. A narrow-band feedforward displacement control scheme based on a model of this subsystem alone was therefore developed and shown to significantly reduce synchronisation errors at the interface.

Modeling and simulation of a high-redundancy direct-driven linear electromechanical actuator for fault-tolerance under various fault conditions

The high-redundancy actuator (HRA) is a linear displacement actuation system, which consists of a large number of small electromechanical actuation elements arranged in a series and parallel configuration. The performance of a HRA with 9 direct-driven linear electromechanical actuators was analyzed under different fault conditions with the aid of the MATLAB simulation model. The results showed that the HRA has the capability to provide inherent fault-tolerance. Hence, the sudden failure of the system in the presence of fault was avoided. However, the capability of the actuator was found to be reduced gradually depending upon the number of faults.

Fault Isolation of an Electro-mechanical Linear Actuator

We apply model-based fault-isolation to an electromechanical linear actuator, and demonstrate its use on an unmanned underwater vehicle mass-shifter. Models incorporating the physics of the motor and of the load, and the effect of the servo-controller, are derived for nominal operations, overload faults, and coupling loss faults. A simple parameter identification method based on close-form solutions during startup and at steady-state is used, and is shown to produce good agreement with measurements. Fault-isolation is done by representing the system as a time-dependent mixture of its models, and selecting the model with the smallest error residual. We tested this in three situations – an actual overload fault, an actual coupling fault, and a false-alarm – and found that the correct model was successfully isolated in each case.

Data-Based Detection and Diagnosis of Faults in Linear Actuators

Modern industrial facilities, as well as vehicles and many other assets, are becoming highly automated and instrumented. As a consequence, actuators are required to perform a wide variety of tasks, often for linear motion. However, the use of tools to monitor the condition of linear actuators is not widely extended in industrial applications. This paper presents a data-based method to monitor linear electro-mechanical actuators. The proposed algorithm makes use of features extracted from electric current and position measurements, typically available from the controller, to detect and diagnose mechanical faults. The features are selected to characterize the system dynamics during transient and steady-state operation and are then combined to produce a condition indicator. The main advantage of this approach is the independence from a need for a physical model or additional sensors. The capabilities of the method are assessed using a novel experimental linear actuator test rig specially designed to recreate fault scenarios under different operating conditions.

Electro mechanical linear actuator using roller screws

Electro Mechanical linear Actuators as the name suggests are linear actuators operated by electric motor. The linear motion is desirable to drive a high inertia weapon system in elevation axis. In this paper, design and development aspects of an Electromechanical linear actuator using Roller screw has been attempted. Initial Comparison with ball screw drive suggests that roller screws are favorable for high dynamic load application. Selection and functional parameters of roller screw had been evaluated to optimize the linear actuator based on roller screw. This paper studies in detail the design aspects of an electromechanical linear actuator. The variation of different parameters with respect to Lead of the roller screw has been studied.

Making a Measured Choice

The trade-offs between pneumatic, hydraulic and electromechanical linear actuators are seldom understood. Here, Eureka! gives a rundown of key criteria when making the selection for your next project.

Modeling and simulation of high redundancy actuator for fault-tolerance

The High Redundancy Actuator (HRA) deals with the intrinsic fault-tolerance actuation by having a large number of small actuation elements coupled in series and parallel configuration. Each actuation element is a linear Electromechanical Actuator (EMA) and these actuators work collectively to form a single HRA. The mathematical modeling and simulation of a HRA having nine actuation elements in 3×3 series-in-parallel configuration are discussed in the present work. The performance of single actuation element as well as 3×3 HRA are projected under both healthy and faulty conditions. Mathematical modeling equations of single actuation element were solved in MATLAB/Simulink module and based on the results obtained, an iconic model of HRA with series-in-parallel configuration was modeled in Simulink/Simscape module. The simulation results are observed in open-loop and closed-loop control of actuation elements under both healthy and faulty conditions. It was observed that there is no sudden failure of actuation, but there is a graceful degradation in the performance of actuation depending upon the number of faulty elements. However, the actuator was in working condition even after three actuation elements are failed.

Development of a high redundancy actuator with direct driven linear electromechanical actuators for fault-tolerance

The High Redundancy Actuator (HRA) deals with the intrinsic fault-tolerance actuation by having a large number of small actuation elements coupled in series and parallel configuration to form as a single actuator. There is a wide range of actuation elements that are suitable for a HRA, but the present work focused on a direct-driven linear Electromechanical Actuator (EMA). The actuation elements are connected in 3×3 series-in-parallel configuration in the HRA. The mathematical modeling of a single EMA was derived and the equations were solved using MATLAB/Simulink module. Based on the results obtained from the mathematical model, an iconic model of HRA with nine actuation elements was modeled using Simulink/simscape module. The performance of the 3×3 HRA was projected in both open and closed-loop under healthy and faulty conditions. It was observed that there is no sudden failure of actuation, but there is a graceful degradation in the performance of actuation depending upon the number of faulty elements. However, the actuator completes the required task even after the failure of three actuation elements within the HRA.