Actual Torque Research Articles

Design of an Adaptive Neural Predictive Nonlinear Controller for Nonholonomic Mobile Robot System Based on Posture Identifier in the Presence of Disturbance

This paper proposes an adaptive neural predictive nonlinear controller to guide a nonholonomic wheeled mobile robot during continuous and non-continuous gradients trajectory tracking. The structure of the controller consists of two models that describe the kinematics and dynamics of the mobile robot system and a feedforward neural controller. The models are modified Elman neural network and feedforward multi-layer perceptron respectively. The modified Elman neural network model is trained off-line and on-line stages to guarantee the outputs of the model accurately represent the actual outputs of the mobile robot system. The trained neural model acts as the position and orientation identifier. The feedforward neural controller is trained off-line and adaptive weights are adapted on-line to find the reference torques, which controls the steady-state outputs of the mobile robot system. The feedback neural controller is based on the posture neural identifier and quadratic performance index optimization algorithm to find the optimal torque action in the transient state for N-step-ahead prediction. General back propagation algorithm is used to learn the feedforward neural controller and the posture neural identifier. Simulation results show the effectiveness of the proposed adaptive neural predictive control algorithm; this is demonstrated by the minimised tracking error and the smoothness of the torque control signal obtained with bounded external disturbances.

A numerical method for evaluating the torque efficiency of hydraulic orbit motors considering deformation effects and frictional losses

This article presents a method for evaluating the torque output of orbit type displacement machines. Orbit machines are commonly used as hydraulic motors, for applications involving low speed and high torque output. The evaluation of the actual shaft torque as well as the hydro-mechanical efficiency in positive displacement machines is a topic that still presents challenges related to the evaluation of the torque losses associated with the functioning of the unit. This paper proposes a method of evaluating the torque efficiency starting from the evaluation of the instantaneous pressurization of each displacement chamber through a lumped parameter approach. From the instantaneous pressure in each chamber of the orbit motor, the contact forces normal to the rotor profiles are evaluated using a contact mechanics formulation accounting for the energy dissipation. The proposed algorithm computes the friction losses at the contact points to evaluate the net torque output of the orbit motor. Besides accounting for the frictional losses, the main elements of novelty of this approach also include the evaluation of the component deformation, instead of making rigid body assumptions.Experiments are performed on a set of reference orbit motor units to evaluate the torque output at different operating conditions. A good agreement between the simulated output torque and the one measured from experiments was observed, in terms of both instantaneous and mean values. The corresponding comparison of mechanical efficiency map is also presented. This shows the potential of the proposed method, which can potentially be extended to other types of gear machines, to evaluate the net shaft torque.

Development of a Prediction Model for Tractor Axle Torque during Tillage Operation

In general, the tractor axle torque is used as an indicator for making various decisions when engineers perform transmission fatigue life analysis, optimal design, and accelerated life testing. Since the existing axle torque measurement method requires an expensive torque sensor, an alternative method is required. Therefore, the aim of this study is to develop a prediction model for the tractor axle torque during tillage operation that can replace expensive axle torque sensors. A prediction model was proposed through regression analysis using key variables affecting the tractor axle torque. The engine torque, engine speed, tillage depth, slip ratio, and travel speed were selected as explanatory variables. In order to collect explanatory and dependent variable data, a load measurement system was developed, and a field experiment was performed on moldboard plow tillage using a tractor with a load measurement system. A total of eight axle torque prediction regression models were proposed using the measured calibration dataset. The adjusted coefficient of determination (R2) of the proposed regression model showed a range of 0.271 to 0.925. Among them, the prediction model E showed an adjusted R2 of 0.925. All of the prediction models were verified using a validation set. All of the axle torque prediction models showed an mean absolute percentage error (MAPE) of less than 2.8%. In particular, Model E, adopting engine torque, engine speed, and travel speed as variables, and Model H, adopting engine torque, tillage depth and travel speed as variables, showed MAPEs of 1.19 and 1.30%, respectively. Therefore, it was found that the proposed prediction models are applicable to actual axle torque prediction.

An improved robot trajectory planning method considering torque saturation and modeling errors

Time-optimal trajectory planning algorithms have been widely adopted to minimize the motion time by exploiting the dynamics and joint allowable torques of a robotic manipulator. However, the actual joint torques may exceed the joint allowable torques because of modelling errors or disturbances in the control system. When the torque limit is added for actuator safety, the controller will have no margin to deal with modeling errors or disturbances, which may lead to large path tracking errors. An on-line trajectory time scaling method called path velocity controller can improve path tracking performance by modifying the path velocity when torque saturation occurs. However, the path velocity controller is based on a feedforward or computed torque controller, so the dynamic modelling errors will worsen the path tracking performance. In addition, the motion time may also be increased because the dynamic modelling errors could result in longer duration time of torque saturation. To further improve the path tracking performance of a path velocity controller, a path velocity controller with an on-line parameter estimate mechanism is proposed. The simulation results show that the proposed method can achieve a better path tracking performance and shorter motion time.

Variable smoothing of optimal diesel engine calibration for improved performance and drivability during transient operation

The model-based method to define the optimal calibration maps for important diesel engine parameters may involve three major steps. First, the engine speed and load domain – in which the engine is operated – are identified. Then, a global engine model is created, which can be used for offline simulations to estimate engine performance. Finally, optimal calibration maps are obtained by formulating and solving an optimisation problem, with the goal of minimising fuel consumption while meeting constraints on pollutant emissions. This last step in the calibration process usually involves smoothing of the maps in order to improve drivability. This article presents a method to trade off map smoothness, brake-specific fuel consumption and nitrogen oxide emissions. After calculating the optimal but potentially non-smooth calibration maps, a variation-based smoothing method is employed to obtain different levels of smoothness by adapting a single tuning parameter. The method was experimentally validated on a heavy-duty diesel engine, and the non-road transient cycle was used as a case study. The error between the reference and actual engine torque was used as a metric for drivability, and the error was found to decrease with increasing map smoothness. After having obtained this trade-off for various fixed levels of smoothness, a time-varying smoothness calibration was generated and tested. Experimental results showed that, with a time-varying smoothness strategy, nitrogen oxide emissions could be reduced by 4%, while achieving the same drivability and fuel consumption as in the case of a fixed smoothing strategy.

Controllable Cellular Micromotors Based on Optical Tweezers

AbstractMicromotors hold exciting prospects in biomedical applications but still face a great challenge. To date, there have been few reports of micromotors with high safety, flexible controllability, and full biocompatibility. Here, a multifunctional method based on an optical tweezer system is presented to realize controllable cellular micromotors. The method not only satisfies all of the above criteria but is also independent of the cell types and materials. Optical tweezers are used to generate a dynamic scanning optical trap along a given circular trajectory, which can trap and drive a microparticle or a single cell to move along the trajectory and thus generate a microvortex. Cells within the microvortex will be controllably rotated under an action of shear stress or torque and their rotation rate and direction can be controlled by changing the scanning frequency and direction of the dynamic optical trap. The proposed method is effective for both immotile target cells and swimming target cells. Additionally, it is further applied to realize synchronous translation and rotation of cellular micromotors and to assemble controllable and fully biocompatible cellular micromotor assays. The proposed method is believed to have potential applications in targeted drug delivery, biological microenvironment monitoring and sensing, and biomedical treatment.

Inertial torques acting on a spinning paraboloid

Numerous gyroscopic devices consist of rotating components that manifest gyroscopic effects, i.e., the action of unexplainable inertial torques. The rotating objects in engineering can be designed as a disk, cylinder, rotor, circular cone, sphere, paraboloid, etc. Known theories express gyroscopic effects by a simplified mathematical model based only on the principle of the change in the angular momentum for the spinning disk. New research in the area of the gyroscope theory has shown that the physics of inertial torques is more complex than that presented in known publications. Spinning objects generate a system of interrelated inertial torques based on the action of centrifugal, common inertial, and Coriolis forces, as well as the change in the angular momentum. The action of inertial torques manifests resistance and precession torques, which is known as gyroscopic effects. These inertial torques constitute the fundamental principles of the gyroscope theory. The rotating objects of complex designs demonstrate the action of inertial torques, in which mathematical models are different from the models of the spinning disk. The novelty of the work is analytical solutions for the inertial torques generated by the rotating mass of the spinning paraboloid that is new in the dynamics of rotating objects.

Power Requirement Estimation for Cutting Paddy Crop Using a Standard Cutter Bar

A laboratory setup simulating the cutting process of a vertical conveyer reaper in the field was developed to study the effect of crop and machine parameters like the number of hills, knife speed, forward velocity of machine on cutting torque, and power requirement for cutting paddy crop. Experiments were conducted by cutting paddy crops at three different levels each of knife speed, forward velocity, and stem area (number of hills). The statistical analysis of data obtained showed that cutting torque was mostly influenced by stem area than knife speed and forward velocity. A minimum knife velocity of 1.8 m/s was required for cutting paddy stems during harvesting. The forward velocity of the machine should be less than 1.1 km/h to prevent excess loading on the knife. A linear model incorporating knife speed and forward velocity with a coefficient of determination of 0.89 was developed to predict the actual torque required to cut paddy crops with different stem areas. A model for predicting total power required to carry out cutting was also developed which included the power required to overcome frictional (idle) torque and cutting torque. Model estimating the total power required for cutting paddy was validated by comparing the measured and estimated values with an average absolute variation of 14.32%.

Investigation on adaptive method of torque characteristic in dual clutch transmission during launch phase

To reduce sliding friction work and clutch judder, an adaptive method of torque characteristic in dual clutch transmission during launch phase is presented in this paper. The proposed approach provides a tool to identify the change of torque characteristic and adapt it in real time. Firstly, to reduce the influence of the error between the nominal engine torque and the actual engine torque, the estimator based on the extended Kalman filter is designed to estimate the transmitted torque of the dual-clutch transmission during launch phase. Furthermore, the torque characteristic adaptive method is presented by a combination of the estimator with the improved Least Square Method. Then, based on the established driveline model of the dual-clutch transmission, the torque characteristic adaptive method during launch phase is validated by MATLAB/Simulink. Finally, in order to further evaluate the application potential of the adaptive method, the experiments are conducted on a production vehicle equipped with the wet dual-clutch transmission. The simulation and experiment results show that the proposed algorithms work well.

Thermodynamic Cycle Analysis of an Automotive Internal Combustion Engine With the Characteristics of the Commercial BMW N54 Spark-Ignition Model

AbstractAn analytical method is presented for the thermodynamic analysis of an automotive internal combustion engine with the characteristics of the commercial BMW N54 spark-ignition model. A 3-L displacement volume, six in-line cylinder, four-stroke gasoline engine is considered with two 0.57 bar boost pressure turbochargers and an air-to-air intercooler. Thermodynamic, fluid flow, and heat transfer phenomena are mathematically analyzed to provide results on the chemical composition of the cylinder gases, on their temperature and pressure, on the amount and properties of the residual exhaust gases, on the volumetric and mechanical efficiencies, on the specific fuel consumption, the torque and brake power output, the thermal efficiency, and the energy balance of the engine. The analysis provides results in very close agreement with the actual torque and brake power characteristics reported by the BMW manufacturer.

Comparison of engine performance of Bajaj Qute RE60 using gasoline and LPG

Bajaj Qute 4 wheel has become a new variant as an alternative to short-distance transportation in several cities in Indonesia. At present, the fleet operates with gasoline. Meanwhile, several fuel stations in several major cities in Indonesia have been equipped with LPG dispensers. Therefore, this study was conducted to compare the torque and power of Bajaj Qute with gasoline and LPG. The test is carried out in chassis dynamometer by the coast-down test method to get the actual torque and power characteristics of the car. The result, even though torque and power with LPG are slightly lower than gasoline, LPG remains promising as an alternative fuel because it is cleaner.

Influence of the geometrical shape on the structural behavior of diagrid tall buildings under lateral and torque actions

Diagrid structural systems are more and more exploited worldwide for the realization of tall buildings, due to their versatility, their capability to realize complex-shaped constructions, and their efficiency in limiting lateral displacements. Plenty of research has been carried out in the last decade aimed at analyzing the structural behavior of these systems, mainly considering buildings with square or rectangular floor plans and commonly investigating only the lateral deformability of the structure. In this paper, we investigate the influence of some geometrical parameters on the structural response of diagrid tubular buildings, under both lateral and torque actions. To this aim, we make use of a matrix-based method (MBM), which was recently developed for the structural analysis of generic diagrid structures. Various building configurations, differing for the aspect ratio, the inclination of the external diagonals, and the floor plan shape, are considered and the structural solutions which allow to minimize the lateral displacements and torsional rotations are thoroughly surveyed.

Four-Wheel Independent Drive Electric Vehicle Stability Control Using Novel Adaptive Sliding Mode Control

Four-wheel independent drive is an important research topic for the future development of pure electric vehicles (EVs) due to its fast response and great flexibility of path tracking. One of the critical issues is to maintain the vehicle motion stability of the four-wheel independent drive (4WID) EV (4WID EV) by appropriately distributing the torque of each wheel. The article presents a hierarchical control structure to counteract the stability problems caused by the actuator faults and road friction uncertainties. Instead of using linear control at the top-level (i.e., the outer control loop), a novel sliding mode controller with adaptive proportional-integral (PI) sliding surface is designed to achieve the required virtual control signal. For the bottom-level controller (or the inner loop controller), dynamic control allocation is employed to optimally allocate the required actual torque for each wheel. The stability of the overall closed-loop system is successfully achieved and proved by using the Lyapunov method. The proposed controller has been tested via simulation and experiments with various actuator faults and road conditions. All the test cases showed the superiority of the proposed method compared to some of the currently existing 4WID control strategies.

Electrical Switching of Tristate Antiferromagnetic Néel Order in α-Fe_{2}O_{3} Epitaxial Films.

We demonstrate nondecaying, steplike electrical switching of tristate Néel order in Pt/α-Fe_{2}O_{3} bilayers detected by the spin-Hall induced anomalous Hall effect. The as-grown Pt/α-Fe_{2}O_{3} bilayers exhibit sawtooth switching behavior generated by current pulses. After annealing by a high pulse current, the Hall signals reveal single-pulse saturated, nondecaying, steplike switching. Together with control experiments, we show that the sawtooth switching is due to an artifact of Pt while the actual spin-orbit torque induced antiferromagnetic switching is steplike. Our MonteCarlo simulations explain the switching behavior of α-Fe_{2}O_{3} Néel order among three in-plane easy axes.

Optimization of Torque Tracking Performance for Direct-Torque-Controlled PMSM Drives With Composite Torque Regulator

In this article, a composite torque regulator is proposed for optimizing the torque tracking performance in direct torque-controlled permanent-magnet synchronous motor drives. In the proposed composite torque regulator, two new variable hysteresis bands are designed and combined with two constant hysteresis bands. In the conventional direct torque control (DTC) scheme, the torque increasing rate and decreasing rate are changed with different speeds and loads. Thus, the average torque will deviate the reference torque seriously under some operation states. With torque deviation, the reference torque can hardly reflect the actual electromagnetic torque, and the torque tracking becomes more difficult and unsatisfactory in dynamic process. On the other hand, the time delay of one sampling period further deteriorates the precision of torque tracking. By introducing the proposed composite torque regulator, both torque deviation and the impact of time delay on the torque ripple can be eliminated. In addition, the advantages of the conventional DTC scheme, namely low switching frequency, fast dynamic response, simple structure, and independence of motor parameters, can be reserved in the proposed DTC scheme with a composite torque regulator. Experimental results are presented to verify the effectiveness of the proposed scheme and compare its performance with the conventional DTC scheme.

A Coupling Dynamic Model for Studying the Physical Interaction Between a Finger Exoskeleton and a Human Finger

This paper presents a coupling dynamic model that is based on a spring-damping contact for modeling and analyzing the physical interaction between the soft exoskeleton and the finger. The physiological structure and biomechanical model of the finger were introduced. According to the movement mechanism of the finger, a bionic prototype of the single-finger model, which is driven by shape memory alloy (SMA) wire, was designed, and its mechanical model was established. A spring-damping model was used to expound an interaction force of a human-robot with a coupling dynamic model. The experiment was carried out to verify the exoskeleton mechanical model and determine the bending angle trajectory of each joint. The inverse solution of the coupling dynamic model was verified by using angle data and driving parameters as input. According to the torque relationship, the actual active shrinkage torque of SMA wire was compared with the simulation data for the circumstances with or without consideration of the interaction contact force. The results confirm that the actual values are consistent with the simulation values. After comparing the actual active shrinkage torque and simulation curve without considering the interaction contact force, the error range is between 0 and $19.57~\text {N}\cdot \text {mm}$ . The comparison that considers the interaction contact force model yields an error range between -0.74 and $10.89~\text {N}\cdot \text {mm}$ . The accuracy of the model is increased by an average of 7.05%.

Development of Prediction Model for Axle Torque of Agricultural Tractors

HighlightsA prediction model was developed for estimating the axle torque of an agricultural tractor.The model was developed by complementing and modifying a previously proposed traction equation.Compared to the actual axle torque, the proposed model attained MAPE of 2.1%, RMSE of 29 Nm, and RD of 2.7%.The model predicted axle torque more accurately than the traction force-based prediction model.Abstract. The tractor driving axle torque is an important factor in optimal transmission design and service life evaluation. Axle torque measurement sensor systems are very expensive, and traction force-based axle torque prediction models cannot accurately estimate the axle torque because they do not consider both the conditions of the tractor and the attached implement. Therefore, in this study, a prediction model was developed to estimate the axle torque of an agricultural tractor based on the traction force equation and motion resistance. A load measurement system was established to verify the developed prediction model, and actual field torque data were collected through field tests. The developed prediction model was verified by comparing the results of five reference prediction methods, including weight, engine-rated torque, and three traction equations (Wismer-Luth, ASABE Standard D497.4, and Brixius), using the measured axle torque. Performance evaluation was conducted based on the main variables, including travel speed, tillage depth, and slip ratio. The proposed prediction model was found to be closest to the 1:1 line at all travel speeds, tillage depths, and slip ratios, implying that it can best explain the measured torque values among all prediction models. Compared to the other prediction models, the proposed prediction model’s results under all variable conditions had an R2 of 0.65, MAPE of 2.1%, RMSE of 29 Nm, and RD of 2.7%, indicating excellent prediction of the measured torque. The results show that the developed prediction model can be applied to axle torque prediction by explaining the actual measured axle torque. Keywords: Agricultural tractor, Axle torque, Prediction model, Torque estimation, Traction force.

Slip reduction method dedicated for autonomous wheeled platforms

The strategy for controlling the wheel devices including a slip phenomenon is presented. Using the proposed model of wheel-ground interaction, the method for longitudinal slip reduction requiring oscillating speed and acceleration of the wheel is designed. The partitioned controller is derived considering the forces acting on a wheel. Referring to the available in literature experimental data, the model of permissible tractive force is proposed as a part of solution. The nominal trajectory of slip reduction is defined as the reference signal. The motion controller takes into account the difference between the actual torque and the torque required for slip reduction considering such trajectory. Selecting the control signal for stable slip reduction the final value theorem is applied. The values of controller parameters must be properly chosen. The method was tested using simulations and experiments. For completeness of considerations the lateral slip is shortly discussed. The simplified formula for lateral slip angle is delivered and general equations describing the controller are given.

The Effect of Combined Tensile‐Torsional Loading Path on the Stress/Strain States of Thin‐Walled Circular Tubes

In this paper, an elastoplastic analysis model of thin‐walled circular tubes under the combined action of axial force and torque is discussed. Based on the von Mises yield criterion and the assumption of isotropic linear hardening, the methods of stress path and strain path loading are analyzed to study the effect of combined tensile‐torsional loading path on thin‐walled circular tubes. A finite element model is used to analyze the loading path effect on thin‐walled circular tubes. A series of tensile and torsional tests are also carried out on 304 stainless steel thin‐walled circular tubes using a universal testing machine. In addition, the consistency of the selected material with the von Mises yield criterion, the assumption of isotropic linear hardening, and other classical elastoplastic mechanics are verified. The theoretical calculation results, the numerical analysis results, and the experimental test results are analyzed and compared. The “primary effect” influenced by the stress path and the “recency effect” affected by the strain path are proved, and their application prospects are discussed. The influence of tensile‐torsional loading path on the final stress and strain states of thin‐walled circular tubes after entering the plastic deformation stage is concretely demonstrated, facilitating the understanding of the principles of the aforementioned two effects. The investigation for a general principle concerning the effect of loading history on the mechanical behavior of engineering materials, based on the classical plastic mechanics, has an important theoretical significance. It is of great theoretical importance for advancements in plastic yield theory and the establishment of more accurate loading conditions suitable for specific materials in engineering practice.

Determination of forces in the elements of the brake rigging of bogies of freight cars

The article presents the results of studies the purpose of which was solving the problem of deceleration of abnormal wear of brake pads in freight cars of Ukrzaliznytsia JSC. In the studies, the design schemes of brake rigging during braking were considered theoretically. Particular attention was paid to the determination of force loads acting in the rods of the rigging and the contact area of the brake pads with the rolling surfaces of the wheels during braking. Design analysis was performed to determine rational solutions from the point of view of determined force load of the rigging elements of the bogies during braking, in particular, taking into account the action of harmful torque caused by the movement of the bogie on inequalities “track joints”. Based on the conducted studies, it was decided to create a 2D generalized model diagram to determine reliable information on the operation of triangle brake rigging.