Torque Calculation Research Articles

Dynamic Stabilization of NAO Humanoid Robot Based on Whole-Body Control with Simulated Annealing

The prime challenge in a humanoid robot is its stability on two feet due to the presence of an underactuated system. In this paper, the complete dynamics of the humanoid robot has been described in essence of torque calculation at the end effectors. Presence of various restraints in humanoid robot motion makes the task of stabilization an even humongous one. Therefore, to neutralize these constraints, whole-body control (WBC) has been proposed to consider the free-floating base and to ensure the stability of the humanoid robot. Dynamic modeling of the humanoid robot is performed based on the Langrage–Euler formalism to obtain the maximum torque at the joints. This approach is utilized to formulate the torque equation and solve the problem of stabilization. WBC deals with the limitation of attainment of well nimble dynamics behavior operated at high speeds. The simulated annealing approach is preferred to tune WBC to get efficient stabilization and eliminate the earlier limitation. In addition, the zero-moment point (ZMP) criterion is taken care of as it affects the stability of the humanoid robot aggressively. Simulations on V-REP are carried out to understand the torque behavior at each joint. To validate the simulation results, the experiments are carried out on the NAO humanoid robot in real experimental conditions. The experimental and simulation results are compared through torque versus time graphs, and they both show good agreement with deviation under 4% between them. The proposed technique is then compared with various previously implemented techniques which confirm the robustness and efficiency of the proposed methodology.

Optimal Torque Split Strategy of Dual-Motor Electric Vehicle Using Adaptive Nonlinear Particle Swarm Optimization

In order to exploit the potential of energy saving of dual-motor powertrain over single-motor powertrain, this paper proposes a time-efficient optimal torque split strategy for a front-and-rear-axle dual-motor electric powertrain. Firstly, a physical model of electric vehicle powertrain is established in Matlab/Simulink platform and further validated by real-vehicle experiments. Subsequently, a three-layer energy management strategy composed of demanded torque calculation layer, mode decision layer, and torque split layer is devised to enhance the total operating efficiency of two motors. Specifically, the optimal torque split strategy using adaptive nonlinear particle swarm optimization (ANLPSO) is embedded in the torque split layer. Finally, two conventional strategies (even distributed strategy and rule-based strategy) for dual-motor powertrain are considered for comparison to verify the efficacy of the proposed strategy. Tremendous results demonstrate that the dual-motor powertrain with this proposed optimal torque split strategy develops energy saving by 11.88% and 12.18% against single-motor powertrain in the NEDC and WLTP. Compared to two conventional torque split strategies, it is able to reduce the total motor loss by 12.17% and 8.1% in NEDC and 11.91% and 8.07% in WLTP, respectively, which indicates the prominent optimization performance and a great potential in realistic applications.

Analytical Model for Cogging Torque Calculation in Surface-Mounted Permanent Magnet Motors With Rotor Eccentricity and Magnet Defects

This article proposes a novel analytical model which combines subdomain method and magnet equivalent circuit (MEC) method to predict the cogging torque of surface-mounted permanent magnet (SPM) motors with rotor eccentricity and magnet defects in any slot-pole combination cases. Firstly, the general solution of open-circuit magnetic field distribution in a slotless SPM motor with magnet defects is derived. Then, the motor is divided into several subdomains along the air-gap circumferential direction to consider the non-uniform air-gap caused by rotor eccentricity, where the air-gap lengths of each subdomain are considered to be uniform. Finally, the methods of conformal mapping and MEC combined with equivalent current is used to consider the effect of slotting and saturation, which is beneficial to improve the calculation precision. The magnetic field distributions and cogging torque calculated by the proposed model are consistent with the results of finite element analysis (FEA). Compared with the FEA, the proposed model can perform fast calculations of air-gap flux density and cogging torque under rotor eccentricity and magnet defects for SPM motors, which can be utilized for optimizing the motor towards fault tolerance.

3D Semi-Analytical Modeling and Optimization of Fully HTS Ironless Axial Flux Electrical Machines

In this paper, a three-dimensional semi-analytical approach, based on the volume integral method, is developed to compute the forces and torque in fully high temperature superconducting (HTS) ironless axial flux machine (IAFM). The use of particular volumetric basis elements helps to speed up the computation of the magnetic field. The Maxwell stress tensor method is used for the force and torque calculations, where the electromagnetic state of the superconductor is taken into account. The developed model is then introduced into a multi objective optimization procedure, based on the genetic algorithms, to maximize the magnetic torque and minimize the superconducting wire length in the considered structure, while respecting the constraints linked to the physical and mechanical properties of the considered HTS tape. It is shown that the considered fully HTS machine has a higher torque density compared to conventional one.

Mechanics of the H-Beam Rolling in the Universal Beam Groove

The formulation and solution of the problem of double-T section rolling in universal groove using the variational principle of minimum total power with aim to determine integral forming and energy-power parameters are presented. Geometrical model of the deformation zone and the kinematically admissible velocity field were constructed accurate within two unknowns: forward slip coefficient ν, flange spread (pulling-down) . The comparison of the calculated values with the experimental data obtained on a laboratory mill 200 confirmed that the variational principle of minimum total power has sufficient accuracy for analysis of double-T section rolling in universal groove. The mean statistical error of torque calculation is 12.3 % while load calculation is 18.7 %.

A Road Identification Method Based on Road Slope Information for Four-Wheel Independent Drive Electric Vehicles

Four-wheel independent drive electric vehicles (4WID EV) drive safely and stably, which depends on current road conditions, especially road friction coefficient and slope, and different driving control strategies are used according to road conditions. Therefore, a road identification method is proposed to estimate the road information. Firstly, we design a road identification algorithm to identify the current road conditions of 4WID EV, and calculate the optimal slip ratio of the current road surface by curve fitting method. When the wheel slip ratio is controlled near the optimal slip ratio, the wheel adhesion coefficient can be maximized to prevent the wheel from slipping. Then, a slope identification algorithm based on Luenberger state observer is designed to identify the various slopes of uphill and downhill, and it provides a reference for the calculation of the slope compensation torque. Finally, through the joint simulation platform of MATLAB/Simulink and Carsim, it shows that the proposed road identification can identify the current road conditions and slope effectively.

Design of Semi Automatic Coconut Dehusker for Small Scale F armers

The removal of shells of coconut and nut has been a problem for lots of years. Foot-operated and hand-operated systems are very in-efficient and in countries like India where large coconut farms are available, it is difficult to employ manpower alone. Efficient methods are necessary for the de-husking of coconut. This paper proposes Double spiked roller arrangement over traditional Dehusking tools and the modern dehuskers. This method employs the use of Single-phase motors instead of conventional three-phase motors. It helps in the reduction of price. The Machine dimensions are designed after various Averages of Coconut dimensions and torque calculations of the Single Phase Induction motor. The machine makes use of the Gear shaft-Pulley powered Single Phase motor which powers the spiked rollers. The rollers dehusk the coconut which when placed on it. It also possesses an adjustable base frame which helps in changing the speed and adjustment of the position of the motor in case Electrical speed varying methods are not available. This machine is extremely useful for small scale farmers because it’s a very low cost, high operating efficiency.

A Novel Approach on the Unipolar Axial Type Eddy Current Brake Model Considering the Skin Effect

The braking torque mathematical modelling in electromagnetic eddy current brake (ECB) often ignores the skin effect that occurrs during operation. However this phenomenon can not be simply neglected. Therefore, this paper presents a mathematical model of braking torque for a unipolar axial type of ECB system with a non-magnetic disk, which considers the skin effects. The use of mathematical models that consider the existence of skin effects is significant in approaching the braking torque according to the actual condition. The utilization of generic calculations to the model of the ECB braking torque leads to invalid results. Hence, in this paper, the correction factor was added to improve the braking torque calculation as a comparator to the proposed equation. However, the modification and addition of the correction factor were only valid to estimate the low-speed regimes of torque, but very distant for the high-speed condition. From the comparison of calculated values using analytical and 3D modelling, the amount of braking torque at a low speed was found to have an average error for the equation using a correction factor of 1.78 Nm, while after repairing, a value of 1.16 Nm was obtained. For the overall speed, an average error of 14.63 Nm was achieved, while the proposed equation had a small difference of 1.79 Nm. The torque difference from the calculation results of the proposed model with the measurement value in the experiment was 4.9%. Therefore, it can be concluded that the proposed equation provided a better braking torque value approach for both low and high speeds.

The role of disc torques in forming resonant planetary systems

Context. The most accurate method for modelling planetary migration and hence the formation of resonant systems is using hydrodynamical simulations. Usually, the force (torque) acting on a planet is calculated using the forces from the gas disc and the star, while the gas accelerations are computed using the pressure gradient, the star, and the planet’s gravity, ignoring its own gravity. For a non-migrating planet the neglect of the disc gravity results in a consistent torque calculation while for a migrating case it is inconsistent. Aims. We aim to study how much this inconsistent torque calculation can affect the final configuration of a two-planet system. We focus on low-mass planets because most of the multi-planetary systems, discovered by the Kepler survey, have masses around ten Earth masses. Methods. Performing hydrodynamical simulations of planet–disc interaction, we measured the torques on non-migrating and migrating planets for various disc masses as well as density and temperature slopes with and without considering the self-gravity of the disc. Using this data, we found a relation that quantifies the inconsistency, used this relation in an N-body code, and performed an extended parameter study modelling the migration of a planetary system with different planet mass ratios and disc surface densities, to investigate the impact of the torque inconsistency on the architecture of the planetary system. Results. Not considering disc self-gravity produces an artificially larger torque on the migrating planet that can result in tighter planetary systems. The deviation of this torque from the correct value is larger in discs with steeper surface density profiles. Conclusions. In hydrodynamical modelling of multi-planetary systems, it is crucial to account for the torque correction, otherwise the results favour more packed systems. We examine two simple correction methods existing in the literature and show that they properly correct this problem.

Torque Calculation of Permanent-Magnet Spherical Motor Based on Permanent-Magnet Surface Current and Lorentz Force

Due to the complex spatial magnetic field distribution and the variable motion mode, the torque analysis of spherical motors is usually carried out by the finite-element method (FEM) with a large amount of calculation and time consumption. In order to improve analysis efficiency, this article proposes a spherical motor torque calculation method based on the permanent-magnet surface current model and Lorentz force, aiming to replace the finite-element calculation. First, the equivalent surface current analytical expression of the rectangular permanent-magnet magnetic field is derived. Then, this expression is used to establish the 3-D magnetic field analytical model of Halbach array permanent magnets in the rotor. Based on this magnetic field, the Lorentz force of the energized stator coil is calculated. Then, the electromagnetic torque generated by the rotor is analyzed. Finally, the analytical results of the magnetic field and the motor torque are compared with those by the FEM and experiments, verified that, under the premise of ensuring the calculation accuracy, the proposed method effectively shortens the calculation time and has higher stability.

Optimization-Oriented High Fidelity NFIR Models for Estimating Indicated Torque in Diesel Engines

In this paper, optimization-oriented high fidelity indicated torque models which cover the whole operating regions under both steady-state and transient cycles for heavy-duty vehicles are developed. Two different experiments are performed and their data are merged to be utilized in the training of the models. In the first experiment, all combustion input channels are excited by quadratic chirp signals with different sweeps in their frequency profiles. Different from the first experiment, the engine speed is excited by ramp-hold signals in the second experiment. The estimations of friction, pumping and inertia torques in addition to the torque measured from the engine dynamometer are utilized in the indicated torque calculations. In order to model the calculated indicated torque, a nonlinear finite impulse response (NFIR) model with a single layer sigmoid neural network has been designed. A sensitivity analysis is performed by generating several models with different number of input regressors and neurons. Experimental results show that the majority of the models in a selected wide range of the model parameters are validated with fit accuracies higher than 90 % and 85 % on the World Harmonized Stationary Cycle (WHSC) and the World Harmonic Transient Cycle (WHTC), respectively.

Study on Calculating Method of External Load on Digging Arm of Underground Excavator Truck

The digging arm of underground excavator truck has many movable joints, complex structure and variable operation properties which results in the complicated loading. So it is difficult to obtain the external working load directly through the test. For this problem, the calculation of the external load on the digging arm of the underground excavator truck is studied by combining test and virtual prototype in this paper. The details include: Firstly, the static test of the digging arm was conducted using pressure sensor and displacement sensor, and the parameters of the virtual prototype built by Motion View software were modified. Then the pressure and displacement curves of each hydraulic oil cylinder are measured during the operation on site. The working process of digging arm is simulated and reconstructed by taking the measured displacement curves of each cylinder as the driving inputs, and outputs the curves of centre of mass coordinate, curves of acceleration and corresponding curves of torque. The rotary torque of external forces and gravity on a rotation axis (rotation axes of movable arm and pitch) should be equal to the sum of torque of the product of each component’s mass and the acceleration of the centre of mass on that point according to the law of torque calculation. Thus, the non-homogeneous linear equations of external loads (horizontal, vertical and lateral loads) are derived under the actual conditions. And external loads were solved by substituting the above curve parameters into the equations. Finally, the obtained external load is reloaded into the virtual prototype of the digging arm to simulate the force of actual digging process. The error is less than 5% by comparing the calculated and test values of the oil cylinders force of rod and bucket and the effective strain error of the movable arm is less than 10%. So the correctness of the derivation method of external load and the dynamic model considering inertial force is verified. It provides theoretical and algorithm support for the next acquisition of load spectrum and fatigue analysis of digging arm.

Application of a Current Sheet in BEM Analysis for Numerical Calculation of Torque in the Magnetostatic Field

Application of a Current Sheet in BEM Analysis for Numerical Calculation of Torque in the Magnetostatic Field

Noninvasive and Improved Torque and Efficiency Calculation Toward Current Advance Angle Determination for Maximum Efficiency Control of PMSM

This article proposes improved mathematical models for torque and system efficiency used toward obtaining accurate current advance angle for maximizing the efficiency of an interior permanent magnet (IPM) synchronous motor. First, improved torque and efficiency calculation procedure that consider the effects of parameter variations, such as inductance, stator resistance and PM flux linkage simultaneously, and motor and inverter losses, have been developed from a combination of analytical models and practical experiments. Subsequently, an offline search procedure has been utilized to determine the optimal current angle using the improved dq -axis-based models. The novelty of the efficiency model is that the method uses preliminary noninvasive experimental tests to consider the saturation and temperature effects simultaneously and successfully determine the relationship between stator and rotor temperatures by using only controller command voltages and currents. Experimental investigations are performed on a laboratory IPM for validating the developed control method through interpolation of improved look-up tables with the derived current angle values for varying speed, torque, and temperature conditions. The effectiveness of the proposed method in improving efficiency is also verified and compared with maximum efficiency and maximum torque per ampere methods using experimental sweep tests.

Fast spacecraft solar radiation pressure modeling by ray tracing on graphics processing unit

A novel method is presented to evaluate on the graphics processing unit (GPU) the force and torque on a spacecraft due to solar radiation pressure. The method employs efficient ray tracing techniques, developed in the graphics rendering discipline, to resolve spacecraft self-shadowing and reflections at faster than real-time computation speed. The primary algorithmic components of the ray tracing process which contribute to the method’s computational efficiency are described. These components include two-level bounding volume hierarchy acceleration data structures, fast ray to bounding box intersection testing using the slab intersection algorithm and fast triangle intersection testing using the Möller-Trumbore algorithm. Spacecraft material optical properties are represented as a combination of Lambertian diffuse and ideal specular reflections. Both diffuse and specular ray-surface interactions are modeled. The approach is implemented using C++ and OpenCL and executed on a consumer grade GPU. Model validation is presented comparing ray traced force and torque values to the same quantities produce by a faceted analytic model. Numerical results illustrate the impact of self-shadowing on the force and torque calculation, and demonstrate the fast computational speed that is enabled with this implementation.

A Concise Transmitted Torque Calculation Method for Pre-Design of Axial Permanent Magnetic Coupler

In this article, a concise and practical analytical method of transmitted torque calculation for pre-design of Axial Permanent Magnetic Coupler (APMC) by combining Faraday's law with magnetic circuit model is proposed. The proposed method is able to consider the three-dimension (3D) edge magnetic effect as well as the induced magnetic field generated by eddy currents. The correctional skin depth factor is also taken into consideration. In order to verify the validity of the proposed method, the 3D finite element method (FEM) is employed. The results present that the relative error between the proposed method and 3D FEM in the normal working slip range is within 5.2%. Finally, detailed analysis is carried out to investigate the influence of the common parameters on the transmitted torque for APMC. Moreover, the deficiencies of this proposed method and the corresponding design considerations are also discussed, which offers useful and auxiliary information for the pre-design of APMCs.

Power and Torque Analysis in Electric Vehicle Prototype Design

Automotive developments led to increased demand for fuel. Vehicle need fossil fuels to move them, while the fossil energy in this world is decreasing over time because fossil energy cannot be renewed. This has triggered the development of the use of electrical energy in the transportation system as a substitute for fossil fuels whose energy source is from renewable energy such as biomass energy (such as methane), hydropower, geothermal power, wind energy, and solar energy. One method that can be done to reduce the use of fossil energy is by utilizing electrical energy as an energy source in cars. In this study, an electric car prototype was designed using a three-phase induction motor with 3 HP power as the main driving force. To find out the power consumption and torque produced, it is necessary to analyze the calculation of power and torque when loaded and without load. In this research, the electric car prototype uses load variants, 40 kg, 60 kg, and 100 kg. Where the maximum torque that can be generated by the motor when no load is 9.94 Nm and when it is loaded is a variation of the load of 100 kg of 11.80 N.m. Calculation of the maximum power that can be generated by the motor when no load is 1976.94 watts and when loaded is a variation of 100 kg of 1202.59 watts. The data from the calculation of torque is inversely proportional to power, where the greater the power, the smaller the torque produced.

Konstrukcija, održavanje i pogon zapornih ventila velikih energetskih postrojenja

The paper analyzes the constructive parameters of all parts of the shut-off valves with a flat seating system designed for operation on the steam pipe with values of temperature and pressure overheated steam 535 °C and 135 bar. All parts of the shut-off valve are given guidelines on the maintenance, packing and repair of possible damage, including the necessary machines, tools, equipment and materials. Based on a good knowledge of the design characteristics of the shut-off valve with flat seating, operating fluid parameters and the torque calculation necessary for rotating the spindle, the dimensioning and selection of an electric actuator for valve operation has been performed. The basic data on the drive, the motor and the control unit of the selected electric actuator are given, as well as the connection forms for the connection of the flange of the electric actuator and the shut-off valve.

A Novel Average Torque Control of Switched Reluctance Motor Based on Flux–Current Locus Control

This article develops a novel average torque control (ATC) scheme for switched reluctance (SR) motor on the basis of a brand-new microstep flux-current locus controller. The proposed ATC is based on the calculation of the average torque from the converted mechanical energy that can be illustrated as an enclosed area in a flux-current plane. It has the superior advantage that it is able to control the average torque over any arbitrary small-angle intervals, whereas the conventional ATC can control only the average torque for a whole stroke. In order to realize the proposed ATC, a flux-current locus controller, which consists of a hybrid flux controller and current controller as well as involve the microstep process, is introduced in this article. The flux-current locus of the energy conversion loop is controlled for the first time in the literature. With the locus controller, it is possible to achieve a better energy conversion ratio and the ATC. In order to verify both the proposed locus control method and the ATC for SR motor, detailed simulation results and discussion are provided.

Analytical Model of Air-Gap Field in Hybrid Excitation and Interior Permanent Magnet Machine for Electric Logistics Vehicles

With the increasing energy shortages and environmental degradation, electric logistics vehicle (ELVs) with energy conservation and environmental protection has become a research hotspot. The design of machine is the key to develop ELVs. Magnetic field analysis is the most critical issue since its accuracy affects the calculation of motor torque, loss, and other characteristics. To provide a calculation method for the field and performance analysis of the machine for ELVs, this paper presents an analytical model of air-gap field for hybrid excitation and interior permanent magnet machine. In the proposed model, it is taken into account for the shape of the stator and rotor teeth. The flux density on the rotor side is derived by equivalent magnetic circuit (EMC) with leakage magnetic flux. Taking the calculated flux density as one of the second boundary conditions, the air-gap field distribution is calculated by magnetic potential model with the eccentricity of the rotor. To verify the analytical method, we adopted the finite element method. The simulation results of the air-gap flux, back electromotive force, and cogging torque are in good agreement with the analytical results. Besides, applying the analytical model, the machine can be optimized for obtaining the optimal air-gap flux density distribution. The hybrid excitation machine with salient pole and interior magnets can provide a good flux density waveform. The study offers a helpful analytical method for design and optimization of the type of machine for ELVs.