Active Torque Research Articles

Neuromuscular Adaptations after an Altitude Training Camp in Elite Judo Athletes.

The aim of this study was to investigate neuromuscular adaptations in elite judo athletes after three weeks of power-oriented strength training at terrestrial altitude (2320 m). Nineteen men were assigned to altitude training (AL) (22.1 ± 2.3 years) and sea level training (SL) (22.6 ± 4.1 years). Neuromuscular assessment consisted of: (1) maximal isometric knee extensor (KE) torque, (2) KE rate of torque development (RTD), (3) quadriceps activity and voluntary activation, (4) soleus H-reflex, (5) quadriceps single (TTW) and double twitch torque (TDB100) and contraction time (CTTW). There were no significant differences between groups at baseline for any of the observed parameters. Significant differences were found between groups in terms of change in RTD (p = 0.04). Cohen’s d showed a positive significant effect (0.43) in the SL group and a negative significant effect (−0.58) in the AL group. The difference between groups in changes in CTTW as a function of altitude was on the edge of significance (p = 0.077). CTTW increased by 8.1 ± 9.0% in the AL group (p = 0.036) and remained statistically unchanged in the SL group. Only the AL group showed a relationship between changes in TTW and TDB100 and changes in RTD at posttest (p = 0.022 and p = 0.016, respectively). Altitude induced differences in muscular adaptations likely due to greater peripheral fatigue.

Design of a Semi-Active Prosthetic Knee for Transfemoral Amputees: Gait Symmetry Research by Simulation

The key technology of the prosthetic knee is to simulate the torque and angle of the biological knee. In this work, we proposed a novel prosthetic knee operated in semi-active mode. The structure with ball-screw driven by the motor and the passive hydraulic damping cylinder was presented. A four-bar linkage was adapted to track the instantaneous center motion of human knee. The mathematical models of hydraulic cylinder damping and active torque were established to simulate the knee torque and angle. The results show that the knee torque symmetry index is smaller than 10% in the whole gait. The knee angle symmetry index value is 34.7% in stance phase and 11.5% in swing phase. The angle in swing phase is closer to the intact knee. The semi-active prosthetic knee could provide similar torque and angle of the biological knee in the simulation. It has shown good potential in improving the gait symmetry of the transfemoral amputee.

Various types of traction synchronous motors for urban use

Asynchronous and valve-inductor (synchronous-reactive) motors have high efficiency at high rotor speeds, while permanent magnet synchronous motors (SPM and IPM) have high efficiency at low and medium frequencies. The latter are the most optimal for urban conditions, and the former for conditions of operation on highways and highways. Synchronous motors with permanent magnets are more expensive, so a good alternative to them can be synchronous-jet motors with permanent magnets, which determine the optimal balance of active and reactive torque, as well as efficiency. Keywords: synchronous motor, asynchronous motor, valve-inductor motor, synchronous-jet motor, permanent magnet, efficiency, operating conditions, reactive torque

CYK-1/Formin activation in cortical RhoA signaling centers promotes organismal left–right symmetry breaking

Proper left-right symmetry breaking is essential for animal development, and in many cases, this process is actomyosin-dependent. In Caenorhabditis elegans embryos active torque generation in the actomyosin layer promotes left-right symmetry breaking by driving chiral counterrotating cortical flows. While both Formins and Myosins have been implicated in left-right symmetry breaking and both can rotate actin filaments in vitro, it remains unclear whether active torques in the actomyosin cortex are generated by Formins, Myosins, or both. We combined the strength of C. elegans genetics with quantitative imaging and thin film, chiral active fluid theory to show that, while Non-Muscle Myosin II activity drives cortical actomyosin flows, it is permissive for chiral counterrotation and dispensable for chiral symmetry breaking of cortical flows. Instead, we find that CYK-1/Formin activation in RhoA foci is instructive for chiral counterrotation and promotes in-plane, active torque generation in the actomyosin cortex. Notably, we observe that artificially generated large active RhoA patches undergo rotations with consistent handedness in a CYK-1/Formin-dependent manner. Altogether, we conclude that CYK-1/Formin-dependent active torque generation facilitates chiral symmetry breaking of actomyosin flows and drives organismal left-right symmetry breaking in the nematode worm.

Reduction of Rotational Vibration Using Coriolis Force Generated by Electromagnetic Oscillatory Actuator Moving in Radial Direction

This article presents a new hybrid dynamic vibration absorber (DVA) using the Coriolis effect to reduce a rotational vibration observed in various kinds of rotating machinery. The Coriolis force is generated by a linear oscillatory actuator (LOA), which reciprocates in the radial direction. The effectiveness of the proposed hybrid DVA is confirmed through a MATLAB/Simulink simulation under passive and hybrid operations of the LOA. Moreover, an active torque ripple control is also presented for the purpose of applying this DVA to a switched reluctance motor (SRM). A numerical simulation shows that the proposed hybrid DVA is able to reduce the torque ripple of the SRM by a nonsinusoidal position control of the LOA.

A Review Paper on Electric Assisted Steering System for Automobiles

Electric Assisted Steering system is an Electric System, which reduces the amount of steering effort by directly applying the output from the electric motor to the steering system.In this system the mechanical link between the steering wheel and road wheels of an automobile are replaced by a control system consisting of sensors, actuators and controllers seem to offer great advantages such as enhanced system performance, simplified construction, design flexibility etc.It offers greater vehicle safety by adapting variable steering ratios to human needs, filtering drive train influences and even adjusting active steering torque in critical situations. In addition, it can make cars even lighter and more fuel efficient when compared to those using hydraulic steering systems. The central electronic elements of today’s steering systems are modern microcontrollers

Comparison of Flux-Switching and Interior Permanent Magnet Synchronous Generators for Direct-Driven Wind Applications Based on Nelder–Mead Optimal Designing

The permanent magnet flux-switching machine (PMFSM) is one of the most promising machines with magnets inserted into the stator. To determine in which applications the use of PMFSM is promising, it is essential to compare the PMFSM with machines of other types. This study provides a theoretical comparison of the PMFSM with a conventional interior permanent magnet synchronous machine (IPMSM) in the gearless generator of a low-power wind turbine (332 rpm, 51.4 Nm). To provide a fair comparison, both machines are optimized using the Nelder–Mead algorithm. The minimized optimization objectives are the required power of frequency converter, cost of active materials, torque ripple and losses of a generator averaged over the working profile of the wind turbine. In order to reduce the computational time, the substituting profile method is applied. Based on the results of the calculations, the advantages and disadvantages of the considered machines were revealed: the IPMSM has significantly lower losses and higher efficiency than the PMFSM, and the PMFSM requires much less rare-earth magnets and copper and is, therefore, cheaper in mass production.

Instrument assisted soft tissue mobilization (IASTM) versus stretching: A comparison in effectiveness on hip active range of motion, muscle torque and power in people with hamstring tightness

BackgroundInstrument-assisted soft tissue mobilization (IASTM) is a new technique that has been known to be effective in reducing muscle tightness in athletics. However, little is known about its effect on the range of motion, muscle power, and torque compared to manual stretching among non-athletics. Thus, the study was aimed to compare the effectiveness between IASTM and manual stretching in improving hip flexion active range of motion (ROM), muscle torque and power on hamstring muscle complex (HMC) tightness in one session. MethodTwenty-three young male college students with unilateral hamstring tightness measured via straight leg raising (SLR) test (<65°) were randomly assigned to one of two groups. Twelve participants received the application of IASTM (group 1), and eleven received manual stretching (group 2). Hip flexion active ROM was measured via goniometer, the torque & power of the hamstring muscle were measured using Humac isokinetic dynamometer, before and after both interventions. (ISRCTN17693345). ResultsThere was no significant difference in the improvement of hip flexion active ROM (69.6 ± 6.6 vs 72.5 ± 7.9, p = .34), HMC torque (63.7 ± 14.5 vs 53.2 ± 16.3, p = .14), and HMC power (47.8 ± 11.8 vs 40.9 ± 16.3, p = .34) between group 1 and group 2 respectively. When a comparison was made within each group, significant improvements in hip active flexion ROM was found in both groups (p's < .001), and HMC power was significantly improved in group 1 (p = .04) but not in group 2. ConclusionThe current study findings demonstrate that IASTM was as effective as manual stretching in improving hip flexion active ROM, muscle torque and power among non-athletic people with HMC tightness.

Paired nonlinear behavior of active and passive joint torques associated with preparation for walk-to-run gait transition

This study investigated the lower extremity torque's active and passive features during the walk-to-run gait transition with continuously increased walking speed. Fourteen volunteers participated in the experiment. Kinematic and kinetic data were collected synchronously. Five strides leading up the gait transition were examined. Peaks of the passive (e.g., contact) and active (e.g., generalized muscle torques), along with net joint torque, and time to peak torques exhibited significant differences at the last stride before gait transition, compared to the first four strides, at the ankle, knee, and hip joints, respectively. Selected peak joint active and passive torques showed significant and opposite trends at critical events within a stride cycle: such ankle joint right after heel-contact, knee joint during weight acceptance, and both hip and knee joints right before toe-off. The magnitude and the corresponding time to active and passive peak torque changed in a nonlinear pattern before the transition from walk to run. The lower extremity segment-interaction during gait transition appeared to be an active reorganization exemplified by the interaction between the lower extremity's active and passive torque components.

Adaptive fuzzy terminal sliding mode control for the free-floating space manipulator with free-swinging joint failure

Space manipulator with free-swinging joint failure simultaneously contains kinematic and dynamic coupling relationships, so it belongs to a new underactuated system. To allow the manipulator to carry on tasks, an effective robust underactuated control method for the space manipulator with free-swinging joint failure is studied in this paper. Considering the effect of model uncertainty and joint torque disturbance, a robust underactuated control system based on the Terminal Sliding Mode Controller (TSMC) is designed, but two drawbacks are discussed: (A) Robustness depraves with eliminating chattering. (B) Control parameters are difficult to be determined under unknown uncertainty and disturbance. To improve the TSMC, the adaptive fuzzy controller is introduced to estimate the real effect of unknown uncertainty and disturbance according to deviations of sliding mode and its reaching law. The estimated result is directly compensated into active joints torque. In simulation, the space manipulator with free-swinging joint executes tasks based on the TSMC and the Adaptive Fuzzy Terminal Sliding Mode Controller (AFTSMC) respectively. Same tasks can be finished with smaller joints torque and stronger robustness based on the AFTSMC. Therefore, AFTSMC can serve as an effective robust control method for the space manipulator with free-swinging joint failure under unknown model uncertainty and torque disturbance.

A cooperative control strategy for yaw rate and sideslip angle control combining torque vectoring with rear wheel steering

ABSTRACT Automobiles are becoming more and more complex as multiple control systems are integrated into the vehicle platform. This paper investigates the coordination of active rear steering (RWS) and torque vectoring (TV) – which is enabled by independent electric motors at the rear axle – in controlling vehicle lateral dynamics. The proposed controller aims at enhancing vehicle handling performance and stability while cornering. The coordination of the two actuators is achieved by weighting their contribution based on their impact on vehicle dynamics according to the working condition. The impact of each control system is assessed by means of phase portraits. These plots are a very powerful tool for analysing vehicle nonlinear dynamics as they readily display vehicle stability properties and map equilibrium point locations and movement to changing parameters and control inputs. Based on phase portrait analysis, a performance index is thus proposed, which weights more the control action (TV or RWS) capable of leading the vehicle at the nearest equilibrium point with the fastest rate. The controller performance is assessed through numerical simulations carried out using a nonlinear 14 dofs vehicle model. Results are compared with ones of the two controllers alone (RWS and TV) in different manoeuvers and adherence conditions.

Identification of Central and Stretch Reflex Contributions to Human Postural Control.

Human postural control requires continuous modulation of ankle torque to stabilize the upright stance. The torque is generated by two components: active contributions, due to central control and stretch reflex, and passive mechanisms, due to joint intrinsic stiffness. Identifying the contribution of each component is difficult, since their effects appear together, and standing is controlled in closed-loop. This article presents a novel multiple-input, single-output method to identify central and stretch reflex contributions to human postural control. The model uses ankle muscle EMGs as inputs and requires no kinematic data. Application of the method to data from nine subjects during standing while subjected to perturbations of ankle position demonstrated that active torque accounted for 84.0± 5.5% of the ankle torque. The ankle plantar-flexors collectively produced the largest portion of the active torque through central control, with large inter-subject variability in the relative contributions of the individual muscles. In addition, reflex contribution of the plantar-flexors was substantial in half of the subjects, showing its potentially important functional role; finally, intrinsic contributions, estimated as the residual of the model, contributed to 15% of the torque. This study introduces a new method to quantify the contributions of the central and stretch reflex pathways to postural control; the method also provides an estimate of noisy intrinsic torque with significantly increased signal to noise ratio, suitable for identification of intrinsic stiffness in standing. The method can be used in different experimental conditions and requires minimal a-priori assumption regarding the role of different pathways in postural control.

An Improved ADRC with RLS for Torque Control of Permanent Magnet Starter

Abstract This paper investigates an improved active disturbance rejection torque controller for the permanent magnet starter of micro gas turbine engine. Based on the motivation of decreasing the workload of the extended state observer and realizing the better control performance, the system disturbance is modeled in advance, and it is compensated actively in the closed-loop system. The following works have been carried out. First, in order to model the system disturbance, we identify the stator resistance, inductance and rotor flux linkage online by the recursive least square with forgetting factors method. Then, we describe the structure of the improved active disturbance rejection controller in detail and the stability of the improved extended state observer is proved. Finally, we verify the proposed controller on the Matlab/Simulink environment, and the tuning rules of different controllers are given. Simulation results illustrate that the parameters can be online identified accurately and the system disturbance can be well modeled. The speed and torque responses of the permanent magnet starter have better control performance and stronger robustness with the investigated controller, compared with the conventional active disturbance rejection controller.

Balance Map Analysis for Visualization and Quantification of Balance in Human Walking.

Evaluation of stability or loss of balance in walking persists as an open question. Although an inverted pendulum model is often adopted to evaluate stance leg balance, a stumbling-related balance loss should be associated with the swing leg. We propose a new framework based on a compass gait model that determines whether the current state (i.e., position and velocity) in the swing phase can maintain steady state walking or, instead, fall without active joint torque, which is termed as balance map analysis. The forward and backward balance loss regions are derived by a linear compass gait model. To test the balance map analysis, measurement experiments of steady state walking and stumbled walking are used to validate two hypotheses: 1) the state during steady-state walking is not located in the balance loss region; and 2) if stumbling occurs, the state moves toward the forward balance loss region. The results of the balance map analysis showed good agreement with our prediction in the hypotheses. The minimum Euclid distance from the balance loss region is defined as the margin, and the margin from forward balance loss rapidly decreased after the stumbling perturbation. The statistical results reveal that the margin from the forward balance loss region after perturbation is significantly smaller than the margin in steady state walking. These results suggest that balance map analysis provides a new aspect of walking balance, expanded for the stumbling and recovery behavior of human walking.The code for the balance map analysis is available at https://github.com/TakahiroKagawa/GaitAnalysis_BM.

Preventing rollover phenomenon with an active anti-roll bar system using electro-hydraulic actuators: A full car model

This paper discusses the role of the active anti-roll bar system in order to enhance the roll stability of cars, thereby preventing rollover phenomenon in high speed emergency situations. First, an integrated full car model is proposed including the longitudinal, lateral, vertical motions and an electro-hydraulic actuator model. In this full car model, the control signal being the input current which is supplied to the actuators to create the active torques to improve the car's stability. This is the most general model in theory to study this active roll control system and is a big step forward compared to previous related studies. The optimal LQR control method has then been used to synthesize the controller based on the integrated model with 26 degrees of freedom. The criteria used to assess the vehicle roll stability are the sprung mass roll angle and the interactive force between the wheels and the road surface. The simulation results in the frequency domain and the validation in the time domain through the CarSim software's nonlinear car model clearly show the advantages of this active system with an optimal LQR controller in preventing vehicle rollover.

Method of Improving Lateral Stability by Using Additional Yaw Moment of Semi-Trailer

The lateral stability control of tractor semi-trailer plays a vital role for enhancing its driving safety, and the distributed electric drive structure of a hub motor creates opportunities and challenges for realising the lateral stability accurately. Based on the dynamics simulation software TruckSim, a nonlinear dynamic tractor semi-trailer model is established, and a MATLAB/Simulink linear three-degree-of-freedom monorail reference model is established. The upper controller adopts fuzzy proportional–integral–derivative control to export active yaw torque values of the tractor and semi-trailer. The lower controller outputs the driving/braking torque of each wheel according to the target wheel driving/braking rules and torque distribution rules. The tractor produce an active yaw torque through conventional differential braking the hub motor is installed on both sides of the semi-trailer, and the active yaw torque is produced by the coordinated control of the driving/braking torque of the hub motor and the differential braking of the mechanical braking system. To prevent wheel locking, the slip rate of each wheel is controlled. Finally, based on the TruckSim–MATLAB/Simulink cosimulation platform, cosimulation is performed under typical working conditions. The simulation results show that the control strategy proposed in this report is superior to the conventional differential braking control (ESP). It can not only improve the lateral stability of the vehicle more effectively, but also improve the roll stability.

Training Intensity and Shoulder Musculoskeletal Physical Quality Responses in Competitive Swimmers.

Shoulder pain is the main cause of missed or modified training in competitive swimmers. Shoulder musculoskeletal maladaptations occur to some extent as a consequence of training loads during swimming that may increase the risk of shoulder injury. Further evidence is needed to understand the training intensities at which these maladaptations occur. To determine the acute effect of training intensity on the shoulder musculoskeletal physical qualities associated with shoulder injury in competitive swimmers. Cross-sectional study. Indoor swimming pool. Sixteen asymptomatic national- and regional-level swimmers (7 females, 9 males; age = 14.6 ± 3.9 years, height = 160.5 ± 12.7 cm, mass = 55.3 ± 12.5 kg). Bilateral active shoulder-rotation range of motion (ROM), joint position sense, latissimus dorsi length, combined elevation test, and shoulder-rotation isometric peak torque and handgrip peak force normalized to body weight were measured before and immediately after low- and high-intensity swim-training sessions. The intensity of the sessions was determined by the distance swum over or at the pace threshold and confirmed by the swimmer's rating of perceived exertion. After the high-intensity training session, shoulder external-rotation ROM (dominant side: P < .001, change = -7.8°; d = 1.10; nondominant side: P = .002, change = -6.5°, d = 1.02), internal-rotator isometric peak torque (dominant side: P < .001, change = -11.4%, d = 0.42; nondominant side: P = .03, change = -6.6%, d = 0.20), and external-rotator isometric peak torque (dominant side: P = .004, change = -8.7%, d = 0.27; nondominant side: P = .02, change = -7.6%, d = 0.25) were reduced. No changes were found in any of the outcome measures after the low-intensity session. Shoulder active external-rotation ROM and rotation isometric peak torque were decreased immediately after a high-intensity training session, possibly increasing the risk of injury during subsequent training. Monitoring these variables may help practitioners adjust and manage training loads to decrease the risk of shoulder injury.

Spatial distribution of lumbar erector spinae muscle activity in individuals with and without chronic low back pain during a dynamic isokinetic fatiguing task

BackgroundIndividuals with chronic low back pain (CLBP) commonly present with increased trunk muscle fatigability; typically assessed as reduced time to task failure during non-functional isometric contractions. Less is known about the specific neuromuscular responses of individuals with CLBP during dynamic fatiguing tasks. We investigate the regional alteration in muscle activation and peak torque exertion during a dynamic isokinetic fatiguing task in individuals with and without CLBP. MethodsElectromyography (EMG) was acquired from the lumbar erector spinae unilaterally of 11 asymptomatic controls and 12 individuals with CLBP, using high-density EMG (13 × 5 grid of electrodes). Seated in an isokinetic dynamometer, participants performed continuous cyclic trunk flexion-extension at 60o/s until volitional exhaustion. FindingsSimilar levels of muscle activation and number of repetitions were observed for both groups (p > 0.05). However, the CLBP group exerted lower levels of peak torque for both flexion and extension moments (p < 0.05). The centre of lumbar erector spinae activity was shifted cranially in the CLBP group throughout the task (p < 0.05), while the control participants showed a more homogenous distribution of muscle activity. InterpretationPeople with CLBP displayed altered and potentially less efficient activation of their lumbar erector spinae during a dynamic fatiguing task. Future studies should consider using high-density EMG biofeedback to optimise the spatial activation of the paraspinal musculature in people with low back pain (LBP).

Development of a novel general reconfigurable vehicle dynamics model

This study presents a novel approach in vehicle modeling to provide a unified reconfigurable vehicle dynamics model. The introduced vehicle model is applicable for analysis, design, and control of a wide variety of vehicles and can be reconfigured for four- and three-wheeled vehicles. Active steering, differential braking, torque vectoring, and active camber are included in the model as the actuators. The proposed set of model equations is reconfigurable and can be adjusted for various vehicles without need for new derivation. Two matrices are defined called the corner reconfiguration matrix and actuator reconfiguration matrix that are responsible for wheel and actuator configurations of the vehicle, respectively. The model can be reconfigured by setting the diagonal elements of these two matrices. The proposed reconfigurable model is compared with different high-fidelity vehicle models in CarSim for validation. Simulation results show that four-wheeled and three-wheeled vehicle models can all be drawn from the single unified reconfigurable model. In addition, the introduced model properly matches the high-fidelity CarSim models for four-wheeled and three-wheeled vehicles.

Adaptive Driver-Automation Shared Steering Control via Forearm Surface Electromyography Measurement

Shared steering control has been developed to reduce driver workload while keeping the driver in the control loop. A driver could integrate visual sensory information from the road ahead and haptic sensory information from the steering wheel to achieve better driving performance. Previous studies suggest that, compared with adaptive automation authority, fixed automation authority is not always appropriate with respect to human factors. This paper focuses on designing an adaptive shared steering control system via sEMG (surface electromyography) measurement from the forearm of the driver, and evaluates the effect of the system on driver behavior during a double lane change task. The shared steering control was achieved through a haptic guidance system which provided active assistance torque on the steering wheel. Ten subjects participated in a high-fidelity driving simulator experiment. Two types of adaptive algorithms were investigated: haptic guidance decreases when driver grip strength increases (HG-Decrease), and haptic guidance increases when driver grip strength increases (HG-Increase). These two algorithms were compared to manual driving and two levels of fixed authority haptic guidance, for a total of five experimental conditions. Evaluation of the driving systems was based on two sets of dependent variables: objective measures of driver behavior and subjective measures of driver workload. The results indicate that the adaptive authority of HG-Decrease yielded lower driver workload and reduced the lane departure risk compared to manual driving and fixed authority haptic guidance.