Torque Compensation Research Articles

Active Vibration Control Strategy for Online Application in a Range Extender

Noise, vibration and harshness are a big issue for hybrid vehicles especially in range extenders. Traditional vibration control and active damping control are generally used for suppressing vibration. Compared with traditional vibration control, active damping control is more flexible and effective in suppressing vibration. The basic idea of active damping control is controlling electric motor compensating for the torque of engine and reducing the vibration from the source. The reduction of vibration is highly depended on the compensation torque of the electric motor. A differently designed compensation torque has a significant impact on the active damping control effect. In this paper, an active damping control method for online application is proposed. And several kinds of compensation torque are designed for this method. Experiments on vibration performance are conducted to compare the effect of different compensation torque design in reducing vibration. And the results show that the compensation torque in the shape of square wave has potential for reducing vibration in all directions. Finally, a guiding tool for compensation design is proposed by correlation analysis and the relationship between designing factors and vibration is revealed.

Control of PMSM Drive Using Lookup Table Based Compensated Duty Ratio Optimized Direct Torque Control (DTC)

There are several ways to reduce the ripple magnitude for direct torque-controlled permanent magnet synchronous motor (PMSM) drives. In this work, the compensated duty ratio optimized direct torque control (DDTC-TC) method was proposed to reduce the ripple for three-phase PMSM. The proposed control strategy employs the simplicity of conventional DTC (CDTC) and compensation of the reference torque to enforce the developed torque to oscillate around the required value. A torque error square minimization technique is employed to determine the duty ratio. The magnitude of the developed torque by the PMSM depends on the torque slope during the active and null voltage periods. The slope of the torque during each period is computed online. Based on the online computed slopes, the magnitude of the switching period and compensation torque were calculated. The ripple reduction capability of the proposed control scheme is tested using Matlab Simulink and a hardware in loop system. Results indicate that the control scheme is effective. Specifically, the torque and speed ripples are very small. The torque ripple during speed fluctuation is less for open-end winding PMSM. In addition, the proposed scheme is tested for four-quadrant operation, and the scheme is effective for four quadrant operation. Finally, verification of the effectiveness of the proposed scheme is performed using OPAL-RT-RT (OP4500). Verification indicates that the proposed scheme is effective.

Research on Dynamic Seal Friction Torque Compensation for a Low-Slow-Small UAV Tracking System

To ensure reliable and accurate operation in a complex field environment for Low-Slow-Small unmanned aerial vehicle (LSS-UAV) tracking systems, a dynamic seal shafting structure consisting of a labyrinthine structure and a magnetic fluid seal ring is designed to protect important equipment, such as the infrared sensor, visible CCD and the laser rangefinder from erosion and oxidation by the external environment. A friction torque model is established for the system’s dynamic seal structure to ensure tracking accuracy of the system. The simulation results show that the closed-loop speed accuracy of the system is improved by nearly 10 fold after adding friction torque compensation. The actual test results show that including friction torque compensation can effectively reduce the start-up delay and speed fluctuation error, and the speed fluctuation error is reduced by more than 80% compared to that without friction torque compensation. The tracking accuracy of the dynamic LSS-UAV is reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$56.44 \mu $ </tex-math></inline-formula> rad to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14.86 \mu $ </tex-math></inline-formula> rad after adding friction torque compensation, which meets the requirement of smooth and accurate tracking for LSS-UAV tracking systems, and verifies the effectiveness and accuracy of compensation for the dynamic seal friction torque.

Robot Zero-Moment Control Algorithm Based on Parameter Identification of Low-Speed Dynamic Balance

This paper proposes a zero-moment control torque compensation technique. After compensating the gravity and friction of the robot, it must overcome a small inertial force to move in compliance with the external force. The principle of torque balance was used to realise the zero-moment dragging and teaching function of the lightweight collaborative robot. The robot parameter identification based on the least square method was used to accurately identify the robot torque sensitivity and friction parameters. When the robot joint rotates at a low speed, it can approximately satisfy the torque balance equation. The experiment uses the joint position and the current motor value collected during the whole moving process under the low-speed dynamic balance as the excitation signal to realise the parameter identification. After the robot was compensated for gravity and static friction, more precise torque control was realised. The zero-moment dragging and teaching function of the robot was more flexible, and the drag process was smoother.

A Study of Reduced Torque Compensation Method Under Temperature Variation Based on Single Torque-Current Lookup Table

In permanent magnet motors, the stator resistance and magnetic flux of the magnet change as the temperature increases. These changes result in a change in the maximum torque point per unit ampere (MTPA) of the motor. Without adequate compensation, this leads to a decrease in output torque. For this reason, look-up table (LUTs) are prepared over the temperature range and used for interpolation. This paper proposes a method to compensate for the output torque reduction due to a temperature increase using only a single LUT prepared at a base temperature. First, an estimation of the magnetic flux linkage and the output torque using a single LUT is performed. Second, the problem is modeled as a limited optimization problem to minimize the loss due to the torque reduction. The magnetic flux linkage and output torque are calculated in real time through the fundamental active power. The compensation value is calculated using the Lagrange multiplier method, an optimization technique, using the estimated magnetic flux linkage and output torque. The proposed method is verified by comparing it with other algorithms through simulation and experiment.

Research on a power smoothing control strategy for energy storage hydraulic wind turbines

AbstractTo solve the problem of large output power fluctuations in wind turbines and improve grid adaptability, a hydraulic energy storage system is introduced in traditional hydraulic wind turbines. Based on the working principle of energy storage hydraulic wind turbines, an energy storage hydraulic wind turbine state space model is established, and the feedback linearization method is introduced to solve the multiplication nonlinear problem in the modeling process. The output power is taken as the control output, and the torque compensation controller is established with the feedback linearization method. The displacement of the variable displacement pump motor is controlled to realize hydraulic energy storage system energy charging and discharging, and the wind turbine output power smoothing control is realized with the fluctuating wind speed. The power smoothing control strategy is verified with the 24 kW energy storage hydraulic wind turbines semi‐physical simulation experimental platform. The proposed control strategy lays the groundwork for the wide application of the energy storage hydraulic wind turbines.

The three-dimensional displacement tendency of teeth depending on incisor torque compensation with clear aligners of different thicknesses in cases of extraction: a finite element study

BackgroundDespite the popularity of clear aligner treatment, the effect of the thickness of these aligners has not been fully investigated. The objective of this study was to assess the effects of incisor torque compensation with different thicknesses of clear aligner on the three-dimensional displacement tendency of teeth in cases of extraction.MethodsThree-dimensional finite element models of the maxillary dentition with extracted first premolars, maxilla, periodontal ligaments, attachments, and aligners were constructed and subject to Finite Element Analysis (FEA). Two groups of models were created: (1) with 0.75 mm-thick aligners and (2) with 0.5 mm-thick aligners. A loading method was developed to simulate the action of clear aligners for the en masse retraction of the incisors. Power ridges of different heights were applied to both groups to mimic torque control, and the power ridges favoring the translation of the central incisors were selected. Then, we used ANSYS software to analyze the initial displacement of teeth and the principle stress on the PDL.ResultsDistal tipping, lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, and mesial tipping and intrusion of the posterior teeth were all generated by clear aligner therapy. With the 0.5 mm-thick aligner, a power ridge of 0.7 mm could cause bodily retraction of the central incisors. With the 0.75 mm-thick aligner, a power ridge of 0.25 mm could cause translation of the central incisors. Aligner torque compensation created by the power ridges generated palatal root torque and intrusion of the incisors, intrusion of the canines, mesial tipping and the intrusion of the second premolar; these effects were more significant with a 0.75 mm-thick aligner. After torque compensation, the stress placed on the periodontal ligament of the incisors was distributed more evenly with the 0.75 mm-thick aligner.ConclusionsThe torque compensation caused by power ridges can achieve incisor intrusion and palatal root torque. Appropriate torque compensation with thicker aligners should be designed to ensure bodily retraction of anterior teeth and minimize root resorption, although more attention should be paid to the anchorage control of posterior teeth in cases of extraction.

Underwater gripping control with waterproof glove for robot hand

With the expansion of robots, researchers have focused on robot tasks with waterproof functions. Although numerous underwater-robot studies have been published recently, there has been minimal research on the waterproofing of robotic hands. The aim of this study is to develop an underwater gripping control strategy for a robot hand using a waterproof glove. By using a silicone-rubber-based waterproof glove, the robot hand finished the underwater gripping task. However, an error occurred during the gripping task because of the resistance force of the glove. To reduce the error, torque control experiments were conducted in two ways. In the first, a grooved glove was fabricated to reduce the resistance force. In the second, a modified control model with torque compensation was employed. In the experiments, it was observed that the torque compensation control model was more feasible than improving the shape of the glove for underwater gripping.

Detection and Compensation of Interturn Short Circuit in Interior Permanent Magnet Synchronous Machines Under Two-Level Voltage Source Inverter Limitations

In this article, proof of concept of interturn short circuit (ISC) detection and shorted turns current reduction with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current injection along with torque compensation is shown. This article evaluates the feasibility of implementing the detection and compensation of an ISC in an interior permanent magnet synchronous machine fed by a two-level voltage source inverter (VSI). First, the proposed method detects the ISC fault using a current observer capable of detecting a specific disturbance related to the ISC. Then, once the ISC is detected, the possibility of compensating for an ISC is evaluated. With a two-level VSI, the options for fault compensation are somewhat limited; however, a significant reduction in the shorted turns current can be achieved by adequately injecting <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current to cancel out the magnetic flux from the permanent magnet. Moreover, a small <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis current can be injected with minimum flux to use the saliency torque. Experimental results obtained from a prototype manufactured specifically for ISC testing proof the feasibility of the proposed technique.

A novel energy-efficient actuator integrated with compact variable gravity compensation module

• Modularized CVGCm by 3D shape design and improved its performance. • Novel energy-efficient actuator that can compensate for the gravitational torque. • Power estimation model of the VGCA based on the Lagrangian method is presented. • Reduced rate of current and power in static and dynamic motion is 63.1 % and 64.0 %, respectively. This paper proposes a new type of energy-efficient actuator called variable gravity compensation module integrated actuator (VGCA). VGCA improves the energy efficiency by compensating the gravitational torque at the target joint. Additionally, the variability of compensation torque can further improve the energy efficiency by dealing with the variation of payload, which is required in many robotic applications. As a core part of the VGCA, a compact variable gravity compensation module, called CVGCm , is a cylindrical compact modular unit based on the cam and variable pivot of the lever mechanism. By the theoretically designed cam and lever profiles, the CVGCm can generate a non-linear compensation torque and energy-free variability. First, the functional principles of CVGCm and VGCA are explained. Next, implementation detail and manufacturing of VGCA are introduced. Subsequently, the power estimation model of the actuator is explained based on the Lagrangian method. The experimental results showed that the CVGCm achieved a rapid change of the compensation torque in the compact module. Furthermore, compared to the actuator without CVGCm, VGCA showed a 63.1% reduction of current in static motion and a 64.0% reduction of power in dynamic motion.

Fault-Tolerant Design Process of Spoke-Type IPM Motor Considering Irreversible Demagnetization of PM in Integrated Electric Brake System

In this article, a novel fault-tolerant design process of the spoke-type interior permanent magnet (IPM) motor is proposed to prevent the increase of cogging torque and torque ripple due to partial demagnetization fault and to minimize the motor size. First, unlike other research papers on the irreversible partial irreversible demagnetization of permanent magnet (PM), in this article, the effect of partial irreversible demagnetization faults on the cogging torque and torque ripple for the fault cases is investigated. Then, a novel fault-tolerant design process is proposed to solve the problem of partial demagnetization faults that increase the cogging torque and torque ripple. In the novel fault-tolerant design process, first, to solve the problem of increasing cogging torque and torque ripple due to the partial demagnetization fault, a process for implementing a uniform irreversible PM demagnetization is proposed. Second, to compensate for the motor torque constant decreased by degraded PM, which is caused by irreversible demagnetization of PM, a torque compensation coefficient is also proposed. The proposed fault-tolerant design process is applied to the motor design for the integrated electric brake (IEB) system that requires high torque density. In the optimal design process, Latin hypercube sampling (LHS), a kriging method, and a genetic algorithm are utilized. To verify the effectiveness of the proposed fault-tolerant design process, it is compared with the conventional optimized design results in which irreversible demagnetization of PM is not allowed at all to prevent the partial demagnetization faults. As a result of comparing the optimal design results, the proposed optimization model utilizing the fault-tolerant design process can significantly reduce the motor volume by 12.9%, compared to the conventional optimization model.

A Novel Sensitivity Analysis to Moment of Inertia and Load Variations for PMSM Drives

A high-performance electrical drive with a permanent magnet synchronous motor (PMSM) should ensure superior dynamic properties, reasonable load torque compensation, and robustness against parameter variations. The performance investigation related to the dynamic properties is usually made using the step response indicators and integral performance indexes. The robustness evaluation is more complex than performance analysis since there are no simple tools for this purpose, especially if it is done experimentally to consider nonlinearities and unmodeled dynamics of the plant. In this article, sensitivity functions suitable for investigating the closed-loop control systems in the time and the frequency domain are proposed, explained, and experimentally verified. Three control schemes designed for the speed control of PMSM are analyzed: a cascade control structure, robust two-degrees-of freedom speed controller, and a cascade-free constrained state feedback controller. Studies are conducted for experimental responses of the drive in the time and the frequency domain to investigate the sensitivity of the PMSM drive against the moment of inertia and load variations. Analysis of nonlinearities influence on the developed sensitivity functions is also presented.

An active multiobjective real-time vibration control algorithm for parallel hybrid electric vehicle

To improve the contradiction between vehicle dynamic performance and ride comfort by using the motor active output torque compensation method to reduce the torsional vibration of the hybrid electric vehicle (HEV) powertrain, an active multiobjective real-time vibration control (AMRVC) algorithm based on model prediction control (MPC) is proposed in this paper, and the current mainstream parallel HEV is taken as the research object to verify the proposed algorithm. Firstly, the torsional vibration model of the parallel HEV powertrain is established, simplified, and verified according to the experimental data, which provides the basis for the multimode adaptability and the application of the controller. Then, based on the state space equation of the torsional vibration system, the MPC controller considering the balance between ride comfort and power performance is designed, which can meet the multiobjective and real-time control effect of the hybrid power system while realizing the active vibration control. Finally, the effectiveness and real-time performance of the AMRVC algorithm are verified by multimode simulation analysis and hardware-in-the-loop (HIL) experiment. The simulation results show that the AMRVC algorithm based on MPC has good real-time application conditions, which can well coordinate the multiobjective requirements of vehicle ride comfort and dynamic performance, and remarkably improve the torsional vibration response of the powertrain by more than 55% in all HEV typical operating modes.

Robot-Assisted Retraction for Transoral Surgery

Tissue retraction is an important task in head and neck surgery to leave space for surgical operations. Because the contact between the retractor and soft tissue is not trivial to model, the retraction operation has not been well addressed by robots in modern robot-assisted surgery. We propose a human-robot collaboration approach to assist the retraction for transoral surgery. The surgeons only need to roughly place the retractors into the oral cavity and specify the recommended retraction force. Robot manipulators will automatically retract the tissues in a safe way. In order to keep the touching force safe, we employ a force-sensing system at the distal end of the retractor. By analyzing the real-time force sensor data, we propose a control strategy which combines active retraction angle compensation and passive torque compensation to adjust the retractor, further reducing potential slippage during the retraction. The proposed method ensures the retraction is adaptive to unknown perturbations of the human anatomy. Our system requires no extra recognition or calibration of the surgical scene or the human tissue models. The approach is validated with two robot manipulators and force-sensing retractors on a physical head phantom as well as a cadaveric experiment. We show that the robots stably retract the mouth under various configurations, where the relative error of the stable retraction force does not exceed 11.8%.

Clutch Mechanical Leg Neural Network Adaptive Robust Control of Shift Process for Driving Robot With Clutch Transmission Torque Compensation

In order to improve the motion accuracy and robustness of the clutch mechanical leg for driving robot (CMLDR), and to improve the shift performance of the driving robot vehicle (DRV) for the engagement operation of CMLDR, a neural network adaptive robust control method of shift process for CMLDR with clutch transmission torque compensation is proposed. First, the dynamics model of the driving robot is established considering an external interference force and dynamic modeling error of the mechanical leg. Second, the upper clutch controller including a two-parameter shift module, a switch controller, and a finite-time linear quadratic regulator of the clutch transmission torque is designed. Third, the estimator of clutch engagement torque through a Kalman filter in the process of shift is constructed. Then, the neural network adaptive robust (NNAR) controller of the mechanical leg is designed. Finally, the proof of stability analysis for NNAR controller is conducted. Experiment and simulation results show that the designed controller of the mechanical leg has a strong antiinterference ability. And the DRV accurately tracks the target speed after compensating for the transmission torque.

FORÇA EXPLOSIVA DOS MEMBROS INFERIORES NO EXERCÍCIO DE PULAR CORDA APLICADO ÀS CRIANÇAS E ADOLESCENTES

ABSTRACT Introduction: The physical health of children and adolescents is directly related to school physical training quality. The improvement of adult sports effectiveness results from a concise protocol with standardized exercises. Rope skipping exercise lacks kinematic studies applied to children and adolescents. Objective: Provide a theoretical reference for jump rope exercise training for children and adolescents. Methods: Eight children aged six to eight years old were recruited to jump at a frequency of 80 and 120 jumps per minute controlled by a metronome. The technique was divided into three stages: impulse, suspension, and landing. Control in the knee joint exoskeleton balance was investigated by computerized baropodometry with differentiation of rotational angular velocity by rotational angular acceleration via Butterworth filter. After noise cleaning and multiplication, an adjustable amplification factor returned to the inlet with inertial compensation torque. Results: Initially, the impulsing force is about three times the individual’s gravity. This value and the center of mass acceleration decrease in time. The initial force is proportional to the velocity of its decrease during the impulse, and the opposite occurs with the landing force. Higher intensity is observed when raising the frequency. Conclusion: The fluctuation in the force curve in the landing phase after 20 jumps indicates low muscle strength in lower limbs to maintain activity. A speed of 80 jumps per minute controlled by music in a playful environment is recommended for children. Evidence Level II; Therapeutic Studies – Investigating the results.

Six-degrees-of-freedom dynamic load identification of compressors for refrigeration system based on rigid body dynamics

Dynamic load of compressors is of great concern to designers of refrigeration products since pipes and sheet metals are easy to be excited, leading to noise or fatigue failure. The excitation is impossible to measure directly and difficult to calculate according to generation mechanism; thus, dynamic load identification which skips the mechanism is a more practicable way. However, the reported approaches have the problems of inaccuracy and clumsy. Therefore, an easy-to-implement approach is proposed, in which the accelerations and the frequency response functions from test are transformed to an arbitrarily given point based on rigid body dynamics, and then the equivalent six-degrees of freedom dynamic load of this point is calculated. This approach is validated using a motor with eccentric mass, whose centrifugal force is identified with the proposed approach and also calculated in analytical way. Comparison indicates that the error is within 5% except for the rotational speeds close to natural frequencies. Curve fitting or interpolation is recommended to correct the data in order to reduce the influence of natural frequencies. Cases studies with a rotary compressor and a scroll compressor respectively are presented. For the rotary compressor, the force magnitudes in X and Y directions are almost the same and pretty close to their quadratic polynomial fitting curves with zero intercept respectively, conforming to the characteristics of centrifugal force; the RZ component is larger than the RX and RY components as expected, but the latter two are not negligible; and there is a step change at 45 rps due to the removal of torque compensation. For the scroll compressor, the force magnitudes in X and Y directions are different, but very close to their quadratic polynomial fitting curves, respectively; the Z component has a jump in high-speed range; and there is no significant difference of dynamic force in the cooling and the heating modes.

Torque Superposition Compensation Fault-Tolerant Control for Dual Three-Phase PMSM with an Inverter Single-Leg Open-Circuit Fault

Dual three-phase permanent-magnet synchronous motors (PMSM) have wide applications in electric vehicles due to advantages such as excellent control performance and outstanding fault tolerance capability. However, present fault-tolerant control of inverter single-leg open-circuit faults cannot make full use of each phase winding of the motor, which limits the torque-production capability. This paper proposes a torque superposition compensation (TSC) control which can minimize the stator copper losses while increasing the torque-production capability. The phase winding originally connected to the faulty inverter leg is then linked to the DC-link mid-point. Thus, the winding in the faulty phase can be utilized to generate an additional torque. The symmetric dual three-phase windings torque model and the asymmetric five-phase windings compensation torque model for Ud/2 voltage level are constructed according to the torque superposition, respectively. Then, the three-subplane decomposition transformation matrix for the post-fault dual three-phase PMSM is derived, and the decoupling model in the d-q subplane is constructed, which achieves the optimal enhancement of the torque-production capability. The simulation results verify the effectiveness of the proposed TSC fault-tolerant control.

Research on Multi-Mode Drive Optimization Control Strategy of Four-Wheel-Drive Electric Vehicles with Multiple Motors

Four-wheel-drive electric vehicles with multiple motors have several advantages such as energy saving, environmental protection, and excellent dynamics performance. Therefore, they have become an important development trend in the field of electric vehicles in the past few years. To deal with the problems of the economy and dynamics optimization of an electric vehicle with dual motors on the front axle and a single motor on the rear axle, a multi-mode drive optimization control strategy based on the hierarchical control architecture is proposed in this paper. In the strategy, the reference torque distribution strategy of the front and rear motors is obtained by optimizing the instantaneous energy consumption power in the economy module, and a torque compensation strategy is formulated based on the fuzzy control in the dynamics module to improve the vehicle dynamics in high dynamics demand conditions. Finally, the closed-loop cycle test and the driver-in-the-loop test are carried out to verify the performance of the strategy proposed in this paper, and the results show that energy consumption is reduced by 6.45% in the World Harmonized Light-duty Vehicles Test Cycle (WLTC), and that vehicles accelerate more quickly in variable acceleration conditions under the proposed strategy.

Systematic design and power management of a novel parallel hybrid electric powertrain for heavy-duty vehicles

A novel multi-degree-of-freedom parallel hybrid propulsion system with multi-gear for heavy-duty vehicles is proposed to optimize fuel economy, driving comfort, and dynamic performance. The system has a compact structure and high integration. The detailed design and the power flow of the parallel hybrid propulsion system are introduced. The full power system prototype is designed and assembled. The control methods for the driving torque compensation and energy management are investigated. The simulated results of the parallel hybrid propulsion system are presented. The propulsion system power is not interrupted during gear shifting with the torque compensation control. The jerk of the vehicle is also reduced during shifting. The internal combustion engine can work more efficiently in the hybrid propulsion mode with the equivalent consumption minimization strategy. The purpose of this paper is to provide a hybrid driving scheme for commercial vehicles.