Torque Range Research Articles

The Nonintuitive Contributions of Individual Quadriceps Muscles to Patellar Tracking.

The purpose of this study was to quantify the contribution of the individual quadriceps muscles to patellar tracking. The individual and/or combined quadriceps muscles were activated in rabbits (n = 6) during computer-controlled flexion/extension of the knee. Three-dimensional patellar tracking was measured for the vastus lateralis, vastus medialis, and rectus femoris when activated alone and when activated simultaneously at different frequencies, producing a range of knee extensor torques. Patellar tracking changed substantially as a function of knee extensor torque and differed between muscles. Specifically, when all quadriceps muscles were activated simultaneously, the patella shifted more medially and proximally and rotated and tilted more medially compared with when vastus lateralis and rectus femoris were activated alone (P < .05), whereas vastus medialis activation alone produced a similar tracking pattern to that observed when all quadriceps muscles were activated simultaneously. Furthermore, patellar tracking for a given muscle condition shifted more medially and proximally and rotated and tilted more medially with increasing knee extensor torques across the entire range of knee joint angles. The authors conclude that patellar tracking depends crucially on knee extensor force/torque and that vastus medialis affects patellar tracking in a distinctly different way than vastus lateralis and rectus femoris, which produce similar tracking patterns.

Vibration and Trajectory Tracking Control of Engineering Mechanical Arm Based on Neural Network.

We offer a neural network-based control method to control the vibration of the engineering mechanical arm and the trajectory in order to solve the problem of large errors in tracking the path when the engineering mechanical arm is unstable and under the influence of the outside world. A mechanical arm network is used to perform tasks related to learning the unknown dynamic properties of a engineering mechanical arms keyboard without the need for prior learning. Given the dynamic equations of the engineering mechanical arm, the dynamic properties of the mechanical arm were studied using a positive feedback network. The adaptive neural network management system was developed, and the stability and integrity of the closed-loop system were proved by Lyapunov's function. Engineering mechanical arm motion trajectory control errors were modeled and validated in the Matlab/Simulink environment. The simulation results show that the management of the adaptive neural network is able to better control the desired path of the engineering mechanical arm in the presence of external interference, and the fluctuation range of input torque is small. The PID control has a large error in the expected trajectory tracking of the engineering mechanical arm, the fluctuation range of the input torque is as high as 20, and the jitter phenomenon is more serious. The use of detailed comparisons and adaptive neural network monitoring can perform well in manipulating the trajectory of the engineering mechanical arm. The engineering mechanical arm uses an adaptive neural network control method, in which the control precision of engineering mechanical arm motion trajectory can be improved and the out-of-control phenomenon of mechanical arm motion can be reduced.

Post‐fatigue ability to activate muscle is compromised across a wide range of torques during acute hypoxic exposure

The purpose of this study was to assess how severe acute hypoxia alters the neural mechanisms of muscle activation across a wide range of torque output in a fatigued muscle. Torque and electromyography responses to transcranial and motor nerve stimulation were collected from 10 participants (27 years ± 5 years, 1 female) following repeated performance of a sustained maximal voluntary contraction that reduced torque to 60% of the pre‐fatigue peak torque. Contractions were performed after 2 h of hypoxic exposure and during a sham intervention. For hypoxia, peripheral blood oxygen saturation was titrated to 80% over a 15‐min period and remained at 80% for 2 h. Maximal voluntary torque, electromyography root mean square, voluntary activation and corticospinal excitability (motor evoked potential area) and inhibition (silent period duration) were then assessed at 100%, 90%, 80%, 70%, 50% and 25% of the target force corresponding to the fatigued maximal voluntary contraction. No hypoxia‐related effects were identified for voluntary activation elicited during motor nerve stimulation. However, during measurements elicited at the level of the motor cortex, voluntary activation was reduced at each torque output considered (P = .002, η p 2 = .829). Hypoxia did not impact the correlative linear relationship between cortical voluntary activation and contraction intensity or the correlative curvilinear relationship between motor nerve voluntary activation and contraction intensity. No other hypoxia‐related effects were identified for other neuromuscular variables. Acute severe hypoxia significantly impairs the ability of the motor cortex to voluntarily activate fatigued muscle across a wide range of torque output.

Control Strategies for Gas Pressure Energy Recovery Systems

In gas transmission, the regulator needs to adjust the gas pressure from high to low. The pressure energy can be then recovered by an expander, and the expander can drive a generator to produce electricity. However, the gas pressure regulator system and generator torque process often present difficult adjustment of PI parameters, and strong non-linearity of the hysteresis comparator and switching table in the traditional direct torque control (DTC) cause difficulties in the controller design and lead to large fluctuations of the generator torque. This paper designs a model predictive controller (MPC) for the gas pressure regulator process to reduce generator torque fluctuations. Simultaneously, a fuzzy PI controller is designed for the generator rotational speed process, and an MPC controller is exploited for the torque process; they operate in a cascaded manner. The fuzzy PI controller is used to calculate the torque set point. And the MPC controller is designed to obtain the optimal voltage vector of the generator for improving control performance through time delay compensation. The simulation experimental results highlight that the fluctuation of the regulator outlet gas pressure is reduced by 7.9% and 8.1%, and the output torque range is reduced by 3.4% and 2.1% compared with the traditional PI control and fuzzy PI control, respectively. The generator torque fluctuation range is reduced by 82.3%, the rotational speed fluctuation range is reduced by 76.9%, and the three-phase current fluctuation range is reduced by 76.6% compared with the traditional DTC.

Torque Optimization Method of a 3-DOF Redundant Parallel Manipulator Based on Actuator Torque Range

Abstract The small actuator torque range brings advantages for the high-accuracy control of a manipulator. By taking the minimum actuator torque range into account, this paper proposes a novel torque optimization method of a 3-DOF redundantly actuated parallel manipulator for friction stir welding. The dynamic model of the 3-DOF redundant parallel manipulator with four kinematic chains is derived by using the principle of virtual work. The solution of the dynamics is not unique, and the range of four actuator torques constitutes a 4D generalized rectangle. A torque optimization method that minimizes the actuator torque range is presented by determining the generalized 4D rectangle with minimum side length. The proposed optimization method is a global solution corresponding to one trajectory of the moving platform, and it is compared with the least square method which is a local solution corresponding to one pose of the moving platform.

Optoelectronic system for controlling an alternating current motor. Electrical and electronic design

A control system for a three-phase induction motor was designed with the use of optoelectronic components and methods. Motor speed was controlled by changing supply voltage frequency. This solution ensures a wide range of rotational speeds, constant torque and effective start-up of an induction motor. The designed motor is supplied with direct current converted to three-phase alternating current. The adopted solution relies on renewable sources of energy to produce DC power. The designed electric motor is controlled by changing supply voltage frequency. Input voltage with the desired waveform is generated by the motor’s electronic system that relies on two microcontrollers. The presented solution features a user interface.

Automatic Shift Control of an Electric Motor Direct Drive for an Electric Loader

Traditional loaders with engines present the drawbacks of high energy consumption and poor emissions performance. The usage of an electric motor instead of an engine in an electric loader can effectively improve energy efficiency and emissions. The loader is mainly used in the earthwork construction of unstructured roads. Compared to the automobile, during the working process of the loader, the load fluctuates violently, and the vibration is serious. A large torque range during operation, a wide speed range during transfer, and frequently switching gears to ensure power are required by the loader. Therefore, the automatic shift control strategy for an automobile cannot be well applied to the loader directly. In this paper, a novel distributed electric motor-driven loader in which the walking drive system and the hydraulic system is decoupled is studied. The shift rule of the electric loader is also studied. A comprehensive automatic shift control strategy considering power and economy is proposed. Simulations are carried out to verify the feasibility of the proposed control strategy. The results show that under the “V” cycle operation condition of the loader, the shift rule meets the control requirements and the shift effect is obvious and reasonable. In terms of transfer conditions, the proposed control strategy yields ideal power performance and energy savings.

External torque sensor design providing wireless and real-time data customized for drivetrain

In this study, a torque sensor design that can be used in both laboratory and field tests simulating road conditions of drivetrain of the vehicles is explained. Mechanical design of the sensor has been carried out via finite element method (FEM). Material of the torque sensor and the relevant heat treatment were determined. Electronic measurement circuit design and its setup have been carried out including amplifier, filter, ADC and data transmission features which are suited for full bridge connection. Verification and calibration tests have been performed with respect to DIN-51309. As a result of the studies, it was determined that the measurement accuracy of the system in the torque range of 250 ÷ 2500 Nm was 0.5%. The effect of noise-induced deviations was found 0.05% for the precision value. Consequently, a verified universal torque sensor has been developed for any drivetrain application under torsional effect with the given specifications. It is hoped that this sensor might become a common feature on any and every drivetrain for advanced monitoring of the drive components.

Ex vivo biomechanical evaluation of Acute lumbar endplate injury and comparison to annulus fibrosus injury in a rat model

Back pain is often associated with intervertebral disc (IVD) degeneration, and IVD degeneration phenotypes are commonly characterized by annulus fibrosus (AF)-driven and endplate (EP)-driven phenotypes. Few studies of EP injury exist in animal models, even though clinical studies show EP lesions are strongly associated with IVD pathology and pain. This project established an ex-vivo rat lumbar EP injury model and characterized effects of EP injury on motion segment biomechanical properties, as compared to AF injury, a common way of inducing IVD degeneration. Lumbar motion segments (39 total vertebra-IVD-vertebra sections) assigned to Intact (L1/L2), AF injury and EP injury (L3/L4 and L5/L6 randomly selected), and biomechanically tested in axial tension-compression, stress-relaxation and torsional testing in pre-injury and post-injury conditions using a repeated-measures design. EP injury involved superior vertebra endplate puncture transcorporeally and obliquely. AF injury involved mid-line punctures anterior and bilaterally. Axial ROM, tensile stiffness, hysteresis, and neutral zone stiffness were significantly affected by EP injury but not AF injury. Torque range, torsional stiffness and torsional neutral zone stiffness were significantly affected by AF injury but not EP injury. Stress-relaxation fast time constant was decreased for EP injury. EP and AF injuries induced distinct biomechanical changes in lumbar motion segments with EP injury having the largest impact on axial biomechanical properties and AF injury most prominently affecting torsional properties. This study deepens the understanding of biomechanical mechanism of EP-driven low back pain and provides methods and biomechanical characterization for future in vivo studies.

Optimal Design of an Interior Permanent Magnet Synchronous Motor with Cobalt Iron Core

The use of a cobalt-iron (VaCoFe) core is investigated as an alternative to silicon-iron (FeSi) in the design of interior permanent magnet synchronous motors (IPMSM). Considering VaCoFe and FeSi cores, a spoke-type IPMSM geometry is optimized for a torque range up to 40 N·m, providing a general comparative analysis between materials. This is done considering the application of a four-motor competition vehicle’s powertrain. A genetic optimization algorithm is coupled to the motor’s electromagnetic and thermal hybrid analytical/finite-element model to provide sufficiently accurate results within a feasible time. VaCoFe allows an estimated increase of up to 64% in torque for the same efficiency level, or up to 5% in efficiency for the same torque. After optimization and using a detailed time-dependent model, a potential 3.2% increase in efficiency, a core weight reduction of 4.1%, and a decrease of 9.6% in the motor’s core volume were found for the VaCoFe at 20 N·m. In addition, for the same motor volume, the VaCoFe allows an increase of 51.9% in torque with an increase of 1.1% in efficiency when compared with FeSi.

Deep Learning Enables Exoboot Control to Augment Variable-Speed Walking

Ankle exoskeletons have the potential to improve mobility, but common controllers are often inflexible to variations in tasks, such as changes in walking speed. To enable effective variable-speed exoboot control, we developed and validated a two-headed convolutional neural network trained to (1) classify stance versus swing and (2) predict the phase during stance, which was then mapped to a desired exoboot torque. This Machine Learning Estimator (MLE) was trained from nine participants walking at three speeds and four exoboot assistance levels. A Time-Based Estimator (TBE) that predicted gait phase from the two previous stride durations was used to apply realistic torques during MLE training and served as a within&#x2013;participant control condition. The MLE was validated online with three new participants walking at a range of speeds and torques, both interpolating within and extrapolating outside the training set. Online validation accuracy (RMSE) across tested speeds and torque levels was 3.9&#x0025;. On a simple walking task in which treadmill speed was varied sinusoidally between 1.1 and 1.6 m&#x002F;s with a 30 s period, the three participants exhibited a mean 5.2&#x0025; decrease in metabolic expenditure with the MLE compared to no-exo (boots only), but exhibited a 5.4&#x0025; increase when walking with the TBE. The MLE more accurately predicted heel strike and toe off events (heel strike Mean Absolute Error: 9.6 ms; toe off MAE: 13.2 ms) than the TBE (heel strike MAE: 19.1 ms; toe off MAE: 34 ms). These positive results validated the potential of using a deep learning model for gait state estimation to effectively control an ankle exoskeleton across variable walking speeds.

CVGC-II: A New Version of a Compact Variable Gravity Compensator With a Wider Range of Variable Torque and Energy-Free Variable Mechanism

This article proposes a new version of a variable gravity compensation mechanism (CVGC-II) for mobile manipulation robots, such as mobile manipulators and exoskeletons. CVGC-II, which incorporated an energy-free variable mechanism in a smaller design space, exhibited improved performance with a wider range of variable torque values. These enhancements were achieved by adopting an optimal curved lever and hybrid spring system. First, the mechanism concept and specifications of the CVGC mechanism are described. Next, the contribution of the curved lever and hybrid spring system to the performance enhancement of CVGC-II is explained. Subsequently, the design methodologies for the main mechanical elements, including the lever, hybrid spring, and cam, are introduced. In the lever design, Hermite spline and B-spline curve model-based optimization is performed to generate the optimal curved shape of the lever. The hybrid spring system, consisting of compression coil springs and layered leaf springs, helps achieve a wider variable range by maximizing the storable energy in a limited design space. The experimental results showed that CVGC-II exhibited a 6.8 times wider variable range and energy-free variable mechanism under 1.5 and 1.3 times smaller size and weight, respectively.

Model-based Fault Detection of Rotor Position Sensor Fault in Permanent Magnet Synchronous Motor for Electric Vehicle

Abstract Permanent magnet synchronous motors (PMSMs) are widely used in drive system of electric vehicles (EVs) because of their high efficiency, wild torque range, high power density, etc. However, rotor position, as a very critical parameter for its control strategy, often faces inaccuracies in operation. In this paper, the problem of position sensor fault detection in drive system of EV was studied. The mathematical model of EV with a specific drive system was introduced in discrete form and built in Matlab/Simulink. Based on the field oriented control strategy model, a novel fault detection scheme based on the parity space for the drive system was proposed. The proposed method considered the influence of the closed-loop control to the fault detection result. A residual generator and a residual evaluator were included. The simulation results demonstrated the effectiveness and applicability of the proposed method.

Simplified Walking Simulation for Tuning a Passive Controllable Ankle Foot Orthosis

A passive controllable ankle foot orthosis (PICAFO) has been developed to treat foot drop on post-stroke patient by controlling the walking gait passively. PICAFO controls the gait by utilizing a proportional integral (PI) controller with an ankle velocity reference. The PI controller must be tuned before being implemented on PICAFO. However, controller tuning based on experimental trial and error is not suggested since it requires the user to use the untuned PICAFO. Therefore, a simplified walking simulation is developed to tune the PI controller using Simulink of MATLAB software. The simulation mainly consists of several parts, such as PI controller, brake model, ankle torque to velocity transfer function, ankle velocity reference, and constant external torque. The result shows that the PI controller can be tuned accordingly to subject’s body mass index (BMI) and the brake model to meet the system specification. In this case, when the subject’s BMI is 22.2 and the brake maximum torque is 1.938 Nm, the system can control the ankle velocity with settling time less than 20 ms. However, if there is an external torque that is outside the range of brake capacities, then the system cannot do the control task. Therefore, improvement in the brake design is necessary in the future to achieve ankle velocity control within wide range of external torque.

Optimization Design and Performance Analysis of a Reverse-Salient Permanent Magnet Synchronous Motor

The reverse-salient permanent magnet synchronous motor (RSPMSM) is a competitive candidate for electric vehicles due to its high torque density and high efficiency. This paper proposes an optimized RSPMSM by adopting a segmented permanent magnet structure. First, the structure, electromagnetic torque, and current control laws of the RSPMSM are introduced in detail. Second, the optimization design method of the RSPMSM is proposed by taking the torque and constant-power speed range as optimized objectives, with the saliency ratio as a constraint. The optimized model of the RSPMSM is determined using the genetic algorithm (GA). Further performance analysis and comparisons are made between the initial motor and the optimized motor. Finally, a prototype is manufactured, and the performance of the RSPMSM is verified through the finite element method (FEM) and experiments.

Comparison of Different Winding Configurations for Dual Three-Phase Interior PM Machines in Electric Vehicles

In this paper, two dual three-phase winding configurations are compared based on the Toyota Prius 2010 interior permanent magnet (IPM) machine. It is found that the winding configuration with single-layer full-pitched (SF) windings can improve average torque and reduce torque ripple in constant torque range. The winding configuration with double-layer short-pitched (DS) windings has better torque performance in a constant power range. The electromagnetic performances of the two winding configurations when one winding set is excited and the other one is open-circuited are also compared. The DS winding configuration shows much better performance under this condition. Overall, the dual three-phase winding configuration with DS windings is preferred for dual three-phase IPM machines in electric vehicles. A Toyota Prius 2010 IPM machine equipped with DS windings was manufactured to verify the analyses presented in this paper.

Non-contact torque sensor based on magnetostrictive Fe30Co70 alloy

A non-contact torque sensor based on a magnetostrictive Fe30Co70 rod wound with an excitation coil and a pickup coil is proposed in this paper. In the magnetic field range 0–30 kA/m, the changing rate and linearity of magnetostriction with a loading magnetic field of Fe30Co70 samples are significantly improved after heat treatment. Maximum magnetostriction is 103 ppm in the annealed sample in the parallel direction, while its tensile strength and allowable shear stress are 608 and 194.56 MPa, respectively. According to the mathematical model presented in this work, there is a linear relationship between the output voltage and torque. An apparent increase in the induced voltage signal (peak voltage) of 48.23 mV is observed as the torque increases to 20 Nm in the case of applying sinusoidal excitation signals. In addition, the experimental results are consistent with the calculated values within the torque range 0–16 Nm, and a good sensitivity of 2.87 mV/Nm is obtained. This work shows the prospect of Fe30Co70 alloy for non-contact torque sensing for the appropriate magnetostrictive property with no orientation requirement.

Development and performance evaluation of a guide vane inclination automatic control system for corn threshing unit based on feedrate monitoring

• Fluctuation in the feedrate requires proper top cover guide vane inclination control. • Proposed control system effectively decreases threshing damage. • Provides a theoretical basis to optimise threshing performance. The crop threshing process and the material movement speed are difficult to control with the fluctuation of feedrate in the longitudinal axial flow threshing unit, which results in the decline of threshing performance. We developed a corn threshing unit with an electric-hydraulic top cover guide vane inclination automatic control system based on the feedrate to overcome these problems. The optimal control model of feedrate and guide vane inclination was established for the control system: When the feedrates were 6, 8, and 10 kg/s, the optimal guide vane inclinations were 22°, 24°and 26°, respectively. Taking the constant guide vane inclination (20°) as the control group, the operational performance of the automatic control system of guide vane inclination was evaluated. The test bench results showed that the steady-state response time was 0.15 s, and the error was maintained within 0.27°, the control algorithm can meet the design requirement. Moreover, results demonstrated that the threshing unit with control system outperformed the one with the constant guide vane inclination, with the average torque range of the threshing rotor axis, average peak torque, the broken grain rate (BGR)、the unthreshed grain rate (UGR) and the grain-entrainment loss rate (EGR) decreasing by 17.39%, 19.03%, 1.63%, 0.06%, and 0.19%, respectively. Thus it can be seen that corresponding to different feedrates conditions, a proper guide vane inclination from the threshing unit with the developed automatic control system could obtain better working quality than the results with constant guide vane inclination.

Design and Optimization of a Large-Stroke Compliant Constant-Torque Mechanism

Compliant constant-torque mechanism (CTM) can produce an output torque that does not change within a prescribed input rotation range. This stability is maintained regardless of complicated sensorized control systems. Owing to the monolithic nature of the compliant mechanism, the device is more compact, lightweight, and portable, which is favorable to human joint rehabilitative devices or mobility-assisting devices. However, before approaching the stable range, the mechanism has to undergo a pre-loading range which usually accounts for one-third of the entire operational journey. In addition, the deformation of flexible segments is restricted due to the yield strength of the materials. This limited working range hampers other potential applications of compliant CTMs. This paper presents a novel design of a compliant 2-stage CTM with long-stroke by using serially connected curved beams that deform sequentially. The design process is implemented via a shape optimization scheme using genetic algorithm. Finite element analysis is used to characterize the constant-torque behavior of the CTM under static loading. A general design formulation is also proposed to synthesize this special kind of compliant mechanism. The results show that this CTM gets the stable torque range from 300 to 1100 over two stages with the deviation less than 4.3%.

Experimental evaluation for fluxes, currents and speed estimation of induction motor

Induction motor drive control and estimation is a wide subject. The market for variable speed drives has grown dramatically in the last few years. Manufacturers have recognized the importance of not only managing the speed or torque range, but also reducing power consumption. This necessitates the development of new control algorithms and schemes to include these solutions. Indeed, the speed estimate must be employed in one or more regions of the control scheme, depending on the control objective. This concept, as well as the most common speed estimation methodologies, is investigated. Currently, many tools can be used for the evaluation of the rotor speed without a speed sensor. By modern signal processing methods, it is possible to implement an estimation scheme with the possibility of monitoring currents and voltages. Therefore, in this paper, the concept of currents, speed and fluxes estimation based on the extended Kalman filter is proposed. By monitoring the ratio of the theoretical residual to the actual residual, the measured noise covariance matrix is recursively corrected online to make it gradually approach the real noise level. So that the filter performs the optimal estimation, improves the accuracy of the speed estimation. The effect of the load change on the currents, fluxes and speed estimation was also studied. Simulation and experimental results show that the proposed improved adaptive extended Kalman estimator has a strong ability to suppress random measurement noise. The experimental and simulation results prove the accuracy of the proposed scheme towards the state estimation of an induction motor at different load levels. It can accurately estimate the speed of the motor and has a good anti-error ability to meet the actual needs of the project.