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For the advantages of oriented silicon steel sheet (OSSS) with better magnetic permeability in the rolling direction, this paper proposes a permanent magnet (PM) torque motor with armature teeth made by OSSS. This paper introduces the influence of unequal tooth width on the winding factor and the width calculation method of the armature teeth tip top, and analyzes the torque performance improvement by OSSS. In the end, based on testing the B-H waves of OSSS, the flux linkage, back electromotive force, rated torque and overload torque of three motors with different structure or material are compared by finite element software. The results show the proposed motor can increase the torque density and overload ability.

The paper covers the problem of reaching the maximum speed performance of a direct drive based on the torque motor. The authors propose the solution to the problem by implementing optimal feed-forward control in accordance with Pontryagin’s maximum principle and Feldbaum’s theorem on the finite number of switching times. Combined control allows a transition from optimal to automatic control in the finite state stabilization zone. Results of mathematical modelling prove the efficiency of selected engineering solutions.

For humanoid/memetic robots, modeling and accurate torque trajectory control of a rotary series elastic actuator (RSEA) is of great importance. In this study, the fuzzy logic torque controller with nonlinear friction compensation (NLFC) is used to improve the deteriorating trajectory tracking performance caused by these nonlinear elements in RSEA systems. In order to demonstrate the power efficiency and performance of the proposed control system, several experiments have been performed on the experimental setup, including a torque motor with worm gear and torsional flat-double spiral spring (TFDSS). The proposed novel RSEA is designed and tested using different controllers, including PID feedforward controller (PID-FFC), fuzzy logic feedforward controller (FL-FFC), and fuzzy torque controller with friction compensation (FTC-FC). A comparative study among controllers is conducted to show the robustness of FTC-FC against a step and ramp-type disturbances. The simulation and experimental results here strongly confirm that the proposed control method produces better control performance.

In this article, a high-precision equivalent magnetic circuit (EMC) model is first proposed for slotted permanent-magnet (PM) limited-angle torque motor (LATM) with nonuniform teeth, which leads to potential application in swing system substituting a lower torque density of the slotless structure. By the proposed relatively fine division method of magnetic reluctance in the stator tooth-tip segments, air-gap regions, and PM poles, the proposed EMC model can fully consider armature reaction and magnetic saturation problem. Subsequently, a multiobjective optimization method based on the EMC model is proposed to improve torque performance. Finite-element analysis is employed to validate the EMC model and optimization results. Following that, a curved nonwounded tooth shape is carried out and further optimized to decrease magnetic saturation of stator teeth and significantly improve symmetry of torque profile about stable equilibrium point, compared with the traditional straight tooth shape. Finally, the slotted LATM with curved teeth is prototyped, and its experimental results are presented and discussed. The simulation and experimental data show better accuracy of torque profile improvement.

It is desirable but difficult to develop wearable robotic devices that have a compact form factor, sufficient range of motion to perform activities of daily living and produce enough force to allow for the manipulation of the environment and objects. Conventional actuation approaches produce high force and power output but require external pressure sources or are heavy and bulky. Twisted string actuators produce high force amplification from low torque motors and require no complicated appendages, making them attractive for wearable robotic devices. However, studies that quantify the performance of twisted string actuators to conventional spooled-motor configuration are lacking. Further, it is difficult to implement bi-directional drive using twisted string actuators without making the system more complicated. In this paper, an in-depth comparison of twisted string actuators to spooled-motor configuration is presented. In addition, a robotic assistive device that leverages the advantages of twisted string actuators is presented. Supercoiled polymer strings are used in the device for both monitoring the position change through resistance changes and simultaneously provide passive force for the glove to return to neutral position. Fingertip force of more than 7 N is achieved with the glove that weighs 186 grams including the electronics. Further, picking everyday objects is demonstrated.

This paper presents a feasible analysis of a foldable robot arm for drones (FRAD) for payload lifting without drone landing. The arm design is aimed to be light, foldable and energy-efficient. FRAD is designed with a scissor mechanism in a parallel arrangement actuated by a twisted string actuator (TSA) with a guide. The robot arm can fold, unfold, and easily deploy on drones by having benefit from inherent TSA advantages. We propose a linkage design approach to provide a solution to mechanical singularity and to improve a space-saving capability. The nonlinear pulling force of twisted strings’ transmission ratio (decreasing with twisting) closely matched the typical force profile requirement for folding the arm. This fact was used in the foldable robot arm for its optimal actuation design. The required string torque and twist angle were calculated to generate a pulling force to fold the arm with a 0.3 kg payload from the unfolded to the fully folded situation. Preliminary experimental trials demonstrated that the proposed FRAD could generate the required lifting force and fold the arm without a high torque motor.

The use of high-precision measuring instruments for determining the torque of electric motors in such areas as medicine, motor transport, shipping, aviation requires the improvement of the metrological characteristics of measuring instruments. This, in turn, requires an accurate assessment of their error. Of particular importance is the measurement of power at high-speed installations, where in some cases conventional measurement systems are either unsuitable or have low accuracy. Thus, the use of high-speed turbomachines in aviation, transport, and rocketry creates an urgent need for the development of high-quality measuring instruments for conducting precise research. In turn, in the absence of means for accurately determining the error, attempts are made to predict them. This makes it possible to timely identify the influence of many factors on the accuracy of measuring instruments. The increase in the error arises, as a rule, through abrupt changes in the measurement conditions. Such errors are unpredictable, and their significance is difficult to predict. In the course of the study, the K-nearest neighbors method was used, to establish criteria for which a gross error may occur. The results obtained make it possible to establish threshold values at which the maximum deviation can be established under various conditions of the experiment. In a computational experiment using the K-nearest neighbors method, the following factors were investigated: vibration; temperature rise of measuring sensors; instabilities in the supply voltage of the electric motor, which affect the accuracy of the strain gauge and frequency converter. As a result, the maximum errors were obtained depending on the indicated influence factors. It has been experimentally confirmed that the K-nearest neighbors method can be used to classify deviations of the nominal value of the error of measuring instruments under various measurement conditions. A metrological stand has been developed for the experiment. It includes a strain gauge sensor for measuring torque and a photosensitive sensor for measuring the speed of the electric motor. Signal conversion from these sensors is implemented on the basis of the ESP8266 microcontroller

In this paper we describe the design, development and functionality of a haptic force-matching device. This device measures precise sensorimotor perception by determining a subject’s ability to successfully attenuate incoming sensory signals. Sensory attenuation provides a novel method of investigating psychophysical aspects of perception and may help to formulate neurocognitive models that may account for maladaptive interoceptive processing. Several similar custom-made devices have been reported in the literature; however, a clear description of the mechanical engineering necessary to build such a device is lacking. We present, in detail, the hardware and software necessary to build such a device. Subjects (N = 25) were asked to match a target force on their right index finger, first by pressing directly on their finger with their other hand, then by controlling the device through an external potentiometer to control the force (indirectly) though a torque motor. In the direct condition, we observed a consistent overestimation of the force reproduced; mean force error 0.50 newtons (standard error = 0.04). In the slider condition we observed a more accurate, yet small, underestimation of reproduced force: −0.30 newtons (standard error = 0.03).

This article presents the theoretical analysis and numerical modeling of various cogging torque suppression methods of the slotted limited angle torque motor (LATM). The relationship between the cogging torque, the output characteristics, and the structure parameters of new methods is revealed by derived equations and finite-element analysis (FEA), which provides a theoretical basis for the optimization of the slotted LATM. The effectiveness of the best suppression method is verified by the prototype experiment. In addition, a method to predict torque distortion caused by armature reaction is proposed and it is verified by the finite-element simulation and prototype experiment.

Due to stator magnetic saturation and inherent cogging torque, the slotted limited angle torque motor (LATM) performs large torque ripple within its operation range, resulting in vibration noise and complex control problem. The novelty of this article is to not only first to apply 1J22 soft magnetic alloy (SMA) in the LATM but also to propose a multiobjective optimization method to improve the torque performances including torque ripple, cogging torque, and output torque, based on genetic algorithm (GA). First, 1J22 SMA is applied to the LATM to reduce the torque ripple caused by magnetic field saturation. Then, through the sensitivity analysis, weight coefficients of the related parameters of stator tooth for the optimization process are obtained. Besides, in order to optimize torque performances, the multiobjective optimization process is carried out and the GA is used to obtain the desired objective. Finally, the finite-element analysis (FEA) is used to validate the optimization design.

The speed-torque characteristics of a torque motor with a new type of active element – the tape winding is considered. The analytical studies of the motor speed-torque characteristics determination is difficult because it is required to take into account the distributed current flowing through the winding elements. This leads to the numerical methods application, in particular, COMSOL Multiphysics software based on the finite element method (FEM). Attention is paid to the changing of the motor developed torque in the presence of EMF created in the winding during the rotor rotation. It is shown that the motor torque with a rotor rotation frequency changing depends mainly on the nature of the distributed current lines flowing through the winding elements, despite the fact that the consumed current value changes to a lesser extent. The obtained speed-torque characteristics of the torque motor has a form similar to ones of separately excited DC motors. The research results allow assessing the expected characteristics of the motor model and are an integral part of the developed design policy of the torque motor with the tape winding stator.

There are scores of bicycles in the world including the mundane one which has to be paddled in order to move, motorized bicycle that utilizes fuel as its crude power and electric bicycle that can only be passable for an hour. Owing to certain discrepancies in the existing system, the motive of a solar bicycle sprung up. The idea is to make the cycle eternally efficient by recharging it whenever it is not in use, with the help of renewable solar energy. The notion of solar energy is that a high torque motor will be put on the bicycle as a result of solar energy. The solar energy will be consumed by the portable solar panel to generate power. The power that has been absorbed can be used directly by the motor if the power conforms to the power requirement. If not, the motor will wield the power from a battery. Whenever the bicycle remains unused during the day, the solar panel will charge its battery. The system would thus make the bicycle operate more efficiently. The controller in electric bicycle controls the flow of power from the battery to the electric motor. The E-bike rider can rely on the motor completely, pedal and use the motor concurrently or pedal only.

A physical and mathematical model is given, along with a computational and analytical description of physical processes in the electric motor and their relationship with the design of its equivalent electromagnetic circuit. The sources are determined and the relationships are investigated when the electromagnetic torque ripples occur. The analytical dependences of the ripples are obtained taking into account the nature of the air gap magnetic conductivity and the currents in the phase windings. It has been determined that the sources of these ripples are the higher harmonics of the air gap magnetic conduction function. The ripples contain three components: ripples of the main, additional and residual torques. It was determined that the amplitudes and phases of the ripple components of the main and additional electromagnetic torques are related to the lead angle of the windings current vector relative to the magnetic flux vector passing through the stator poles of the electric motor. The results were confirmed by numerical simulation of the electric motor electromagnetic system by the finite element method in ANSYS Maxwell. These results can be used to improve the designs of this type of electric motor, as well as in the development of circuit solutions and control algorithms for precision gearless electric drives of automatic control systems.

According to the requirement of stabilization precision of 0.2 mrad for artillery aiming line in upper anti-stabilization aiming system, a multi-closed control loop was formed by adding high gain acceleration closed-loop correction in traditional inertia rate stable closed-loop, and the PID parameters of the system were adjusted by integral of time-weight absolute error (ITAE) optimal control. The structure of the upper anti-stabilization aiming system was introduced and analyzed, and the closed-loop control system was simulated, such as load, gyro and brushless torque motor. The ITAE optimal controller was used to adjust the PID control parameters of the multi-closed-loop control system. Added random interference and unit step response to the system in order to test the related performance. The test results show that compared with the traditional adjustment of PID parameters and single-speed-loop control system, the multi-closed-loop ITAE optimal controller based on acceleration can improve the system anti-disturbance performance by 78%, the overshoot is reduced by about 23%, and the swing stability accuracy is improved by about 29%, which can better meet the stability requirements of the upper anti-stabilization aiming system.

Nonlinear mathematical model (NMM) of limited-angle torque motor (LATM) is rarely studied at present because its operating principle is different from conventional rotating electrical machines. In this article, inspired by the NMM of rotating electrical machines, a high-fidelity and computationally efficient model of LATM is proposed, which can completely consider the nonlinear effects, including the electromagnetic torque, flux linkage, and inductance variation with current and rotor position due to magnetic saturation in the stator core. Different from the field-circuit coupling approach (FCCA) considering nonlinear effects, the proposed model exhibits higher computational efficiency since a finite element analysis (FEA) is not involved in the time-stepping simulation. Based on the high-fidelity model, an LATM position-tracking system model is built to simulate the real operation of the LATM system, which provides an accurate means of assessing the position-tracking performance without the actual test platform. The high fidelity of the proposed LATM model is validated by both the FCCA and experimental results.

The magnetization and demagnetization process of electrohydraulic servo valve with permanent magnet torque motor is the last manufacturing process of electrohydraulic servo valve before its service, which has a significant effect on the output characteristics and magnetic stability of both torque motor and electrohydraulic servo valve. However, the previous studies mainly focus on the static state of the magnetic circuit instead of the changes of the magnetic steel’s states while operating magnetization and demagnetization process of torque motor, which causes many issues such as the unpredictability and inaccuracy of magnetization and demagnetization process. In this paper, a set of theoretical models are proposed to describe this entire magnetization and demagnetization process more accurately aiming at this issue. Firstly, a detailed magnetic circuit mathematical model of permanent magnet torque motor before demagnetization is established according to two kinds of magnetic circuits. Secondly, different from the existing research, in this paper, taking the variety of internal reluctance and magnetomotive force of magnetic steel into consideration, an equivalent method is presented by dividing the B-H curve of the magnetization and demagnetization process into several segments. Finally, the finite element method is used to verify the accuracy of the proposed mathematical model. The research results show the proposed model can accurately calculate the magnetic flux density of magnetic steel at any time and even the air gap’s magnetic flux and the output torque after the magnetization and demagnetization process. This research can help to design the magnetization and demagnetization process such as demagnetizing current to make sure the toque motor meets the requirements, which has an important guiding significance to design and conduct the magnetization and demagnetization process of electrohydraulic servo valve with permanent magnet torque motor.

Energy management strategy (EMS) of plug-in hybrid electric buses (PHEBs) has a very important impact on the fuel economy. Currently there is still huge room to improve the performance of EMS, regarding the optimisation and real-time application potentials. With the rapid development of intelligent transportation systems, the emerging technologies, such as telematics, remote vehicle monitoring, cloud optimisation, and so on, provide an opportunity to realize this goal. Based on this, this study proposes an event-triggered intelligent EMS for PHEBs. Taking the demand torque of PHEB and the battery's state-of-charge as the inputs, and the electric motor torque as the output, triangle and trapezoid membership functions are chosen to construct a specialised fuzzy controller to accomplish torque split task in the studied PHEB. To further improve the fuzzy controller, an enhanced genetic algorithm is proposed to optimize its membership function parameters. Furthermore, to reduce the calculated load in the vehicle cloud optimisation process, an event-triggered mechanism is introduced. Finally, the proposed strategy is verified, and results show that the proposed strategy improves the fuel economy of the studied PHEB by 19% and 22% over that using the rule-based strategy, under the real-world driving cycle and China typical urban driving cycle, respectively.

Highlights • The history of dependence of force is known to increase a muscle's force-producing capacity following active lengthening (residual torque enhancement) (rTE) compared with a fixed-end isometric contraction at the same muscle length. • Despite marked differences in neuromuscular activation during force-matching and position-matching tasks, the implications of rTE during position tasks on activation reduction has not yet been explored. • In the rTE state, activation reduction was present for both force- and position-matching tasks. • rTE is a feature of controlling a positional contraction, which better represents various tasks of daily living as compared with a force-matching isometric contraction., Background Residual torque enhancement (rTE) is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation. In the rTE state, owing to an elevated contribution of passive force to total force production, less active force is required, and there is a subsequent reduction in activation. In vivo studies of rTE reporting an activation reduction are often performed using a dynamometer, where participants contract against a rigid restraint, resisting a torque motor. rTE has yet to be investigated during a position task, which involves the displacement of an inertial load with positional control. Methods A total of 12 participants (6 males, 6 females; age = 22.8 ± 1.1 years, height = 174.7 ± 8.6 cm, mass = 82.1 ± 37.7 kg; mean ± SD) completed torque- and position-matching tasks at 60% maximum voluntary contraction for a fixed-end isometric contraction and an isometric contraction following active lengthening of the ankle dorsiflexors. Results There were no significant differences in activation between torque- and position-matching tasks (p = 0.743), with ∼27% activation reduction following active lengthening for both task types (p < 0.001). Conclusion These results indicate that rTE is a feature of voluntary, position-controlled contractions. These findings support and extend previous findings of isometric torque-control conditions to position-controlled contractions that represent different tasks of daily living., Graphical abstract Image, graphical abstract

To achieve better trajectory tracking of the autonomous ground vehicle (AGV), a dual-motor autonomous steering structure and control method are proposed. The model predictive control (MPC) algorithm is utilized to calculate the optimal front wheel angle in real time based on the vehicle information, and dual-motor steering system follows the target angle to achieve trajectory tracking. In this process, to improve the stability of the angle motor, a coordinated steering controller of the angle motor and torque motor is proposed, and the type-2 fuzzy logic is designed based on the target front wheel angle and vehicle speed to optimize coordination coefficient. The front wheel angle step input and double-lane change trajectory tracking conditions are simulated in the carsim and simulink joint simulation platform, the results show that dual-motor steering system has good trajectory tracking ability, compared with no coordinated control, the current and velocity of angle motor are more stable under the coordinated steering control, which greatly reduces the steering load of the angle motor under different working conditions. The final hardware-in-loop test is put forward to verify the effectiveness of the MPC controller and coordinated steering controller.

This article presents the theoretical analysis, numerical modeling and experimental verification of a novel limited angle torque motor (LATM) with an irregular slot number. Based on the magnetic circuit, analytical equations are derived for predicting the torque-angle characteristic of the LATM, including both the constant torque region and linear region. By these equations, the relationship between the performance and leading parameters is established, providing a reference for the quick design of LATM. The idea of utilizing the linear region to expand the angular operation range of LATM is then proposed. It is shown that by active control of the winding current, the linear region can be reasonably used. Due to larger cogging torque in the integral-slot LATM, an irregular slot number topology is proposed to suppress the cogging torque. The results are validated by finite element analysis, and further verified by experimental measurements on a prototype machine.