Inertia Torque Research Articles

Analysis of Selected Operating States of the Line Start Synchronous Reluctance Motor Using the Finite Element Method

The article presents the results of work on an effective numerical study of selected transient states of a low-power electrical machine. The object of detailed research was a synchronized squirrel-cage induction motor. Its ability to work at a synchronous speed was enabled by obtaining reluctance torque, caused by an imposed asymmetry between the direct and quadrature reluctances of the rotor. The difference between the reluctances was achieved by changing the rotor geometry by milling additional deep grooves. The modifications of the rotor did not damage the continuity of the rotor cage. Imposed lots were arranged symmetrically around the rotor circumference. In order to study the performance of the modified motor, a parameterized, numerical model of the machine was developed to evaluate the impact of the geometry of the slots. The developed three dimensional (3D) model of the electromagnetic phenomena in the studied magnetic circuit employs the finite element method (FEM). The model takes into account the saturation of the machine’s magnetic circuit and the skew of the rotor cage bars as well as the mechanical equilibrium of the terrain system including the moment of inertia and frictional torque in the bearings as well as the load torque resulting from the operation of the internal fan. The simulation study concerned the starting process of the machine under different values of the load. The influence of the supply voltage phase angle at the moment of start-up and the initial position of the rotor in relation to the stator was investigated. In order to calibrate the model, tests of the physical object were performed. The corrections introduced concerned the magnetization characteristics of the magnetic circuit. The results obtained confirm the correctness of the adopted strategy of testing the operational properties of the considered engine.

Neural adaptive attitude tracking control for uncertain spacecraft with preassigned performance guarantees

In this article, two novel neural adaptive attitude control strategies are presented for the attitude tracking of rigid spacecraft affected by inertia uncertainty, external disturbance, and torque saturation with guaranteed prescribed performance. Under the backstepping framework, a neural adaptive state feedback controller is designed first by utilizing the neural network (NN) approximation and barrier Lyapunov function (BLF). Then, on the basis of the state feedback controller, a neural adaptive output feedback controller is exploited by integrating with a high-gain observer. Lyapunov stability analysis shows that all the closed-loop error signals are uniformly ultimately bounded under the both proposed neural adaptive attitude controllers. In comparisons with the most existing researches, the distinctive advantages of the proposed neural adaptive attitude controllers are threefold. (1) With the help of NN approximation, the proposed attitude controllers are model-independent and still applicable even when the spacecraft attitude dynamics are completely unknown. (2) Benefiting from the BLF, the proposed attitude controllers can guarantee the attitude tracking error always satisfies the preassigned performance. (3) Both the state feedback control and output feedback control are considered. The angular velocity information of the spacecraft is not required for the output feedback control design. At last, numerical simulations and comparisons are conducted to verify and highlight the proposed neural adaptive attitude control strategies.

A Theoretical Analysis of Magnetic Particle Alignment in External Magnetic Fields Affected by Viscosity and Brownian Motion

The interaction of an external magnetic field with magnetic objects affects their response and is a fundamental property for many biomedical applications, including magnetic resonance and particle imaging, electromagnetic hyperthermia, and magnetic targeting and separation. Magnetic alignment and relaxation are widely studied in the context of these applications. In this study, we theoretically investigate the alignment dynamics of a rotational magnetic particle as an inverse process to Brownian relaxation. The selected external magnetic flux density ranges from 5μT to 5T. We found that the viscous torque for arbitrary rotating particles with a history term due to the inertia and friction of the surrounding ambient water has a significant effect in strong magnetic fields (range 1–5T). In this range, oscillatory behavior due to the inertial torque of the particle also occurs, and the stochastic Brownian torque diminishes. In contrast, for weak fields (range 5–50μT), the history term of the viscous torque and the inertial torque can be neglected, and the stochastic Brownian torque induced by random collisions of the surrounding fluid molecules becomes dominant. These results contribute to a better understanding of the molecular mechanisms of magnetic particle alignment in external magnetic fields and have important implications in a variety of biomedical applications.

Low-Cost Experiment to Determine the Moment of Inertia of the Fidget Spinner by Video Analysis

In this article, we present a low-cost lab experience, enhanced by new technologies and easy to execute. The objective of the experiment is to explore the moment of inertia of a fidget spinner quantitatively. Our choice was to integrate the teaching of physics with the use of a popular toy, the fidget spinner, very popular among young people and children all over the world. There are several papers with teaching suggestions regarding the fidget spinner that have been developed recently. Various physical concepts can be demonstrated with the fidget spinner, for example, angular speed, torque, and moment of inertia. The experience developed here can be used by teachers from high schools, colleges, and universities.

A rotating body about the fixed point is subjected by inertial torques

A rotating body about the fixed point is subjected by inertial torques

Design and analysis of permanent magnet synchronous servo motor with low rotational inertia and high torque density

Aerospace servo motor has the characteristics of strong load capacity, fast response and high control accuracy. To satisfy the design target of high dynamic performance and low weight, the high magnetic loading ironless-core array rotor structure is applied to balance the low rotational inertia and high torque density of permanent magnet servo system.

An assistive upper-limb exoskeleton controlled by multi-modal interfaces for severely impaired patients: development and experimental assessment

Active exoskeletons can help adults with muscular dystrophy regain independence and self-esteem, which have been limited due to their severe and progressive muscular weakness. A four degrees-of-freedom fully actuated upper limb exoskeleton, equipped with a spring-based anti-gravity system, has been designed, prototyped, and tested on end-users. While wearing the exoskeleton, the user directly controls the system by actively driving the end-effector position (i.e., the hand) using a joystick or vocal control. The exoskeleton’s kinematic model has been determined so that, given a desired user’s position in the task-space, a differential inverse kinematics algorithm computes the desired joint-space motion trajectories. The dynamic model was investigated in the vertical plane, demonstrating that gravity torques were considerably higher than velocity-induced and inertia torques, which have been therefore neglected. A pilot study on 14 Muscular Dystrophy patients was conducted. Outcome measures included: (i) externally-assessed functional benefit evaluated through the Performance of Upper Limbs module, (ii) self-perceived functional benefit assessed through the ABILHAND questionnaire, and (iii) usability of the system assessed through the System Usability Scale. All participants strongly increased their range of motion, and they were able to perform activities that were not possible without the exoskeleton, such as feeding. The externally-assessed and self-perceived functional improvements were statistically improved when wearing the exoskeleton (PUL p-value=0.001, ABILHAND p-value=0.005). System usability was evaluated to be excellent. Patients’ feedbacks were encouraging and outlined future development steps.

A 4-DOF SCARA Robotic Arm for Various Farm Applications: Designing, Kinematic Modelling, and Parameterization

Abstract The agriculture industry has faced various challenges nowadays. This research is the first part of a project that presents the designing process, kinematic modelling, and parameterization of a 4-DOF SCARA-type robotic arm specifically designed for work in an agricultural field in terms of seeding, watering, fertilizing, weeding, harvesting, and transporting. The designing of parameters, such as optimum degrees of freedom and component configuration, was done. The kinematic model was calculated using the Denavit-Hartenberg method. The structure of robot was developed for inertia reduction, smooth motion, and torque minimization. The results show that the working space, maximum front access, and side access of developed robotic arm were 11.4 m2, 2.9 m, and 2.4 m, respectively. The results indicate that the robot has sufficient surface coverage for defined farm work.

The Mathematical Model for the Tippe Top Inversion

The dynamics of rotating objects is an area of classical mechanics that has many unsolved problems. Among these problems are the gyroscopic effects manifested by the spinning objects of different forms. One of them is the Tippe top designed as the truncated sphere which is fitted with a short, cylindrical rod for rotation. The unexplainable gyroscopic effect of the Tippe top is manifested by its inversion towards the support surface. Researchers tried to describe this gyroscopic effect for two centuries, but all modelings were on the level of assumptions. It is natural because the Tippe top has a more complex design than the simple spinning disc, which gyroscopic effects did not have an analytical solution until recent time. The latest research, in the area of gyroscopic effects, reveals the action of the system of several interrelated inertial torques on any spinning object. The gyroscopic inertial torques are generated by their rotating mass. These inertial torques and the variable ratio of the angular velocities of the spinning object around axes of rotations constitute the fundamental principles of gyroscope theory. These physical principles of dynamics of rotating objects enable to description and compute of any gyroscopic effects and also the Tippe top inversion.

Improving ISLE-based STEM learning outcomes for building the 21st century skills and characters through a lesson study: A case study on Torque and Moment of Inertia

The objectives of this study are as follows: (1) Developing ISLE-based STEM learning media, (2) Building 21st-century skills and character, (3) Analyzing the improvement of learning outcomes through lesson study. This research is a descriptive quantitative study developed at the STEM UNSYIAH Research Center and carried out at Unsyiah Laboratory High School. The instruments used in this study are validation rubric for media and material experts and Teacher Observation sheets and monitoring sheets for the increasing 21st-century character. Based on the data analysis: 1) Validation of the Moment of Inertia props from 2 media experts obtained an average percentage value of 86.4% with an excellent category. 2) Validation of Student Worksheet by two validators expert in material teaching obtained an average percentage value of 84.77% with an excellent category. 3) The teaching and learning results using teaching aids and LKPD through a Lesson Study conducted by the observer obtained a percentage with an average of 83.5% excellent category. 4) There is an increase in 21st-century character in students by 77% with an excellent category. ISLE-based STEM Learning Media is very suitable for improving 21st-century skills.

Multivariable model predictive control of a compound power-split hybrid electric vehicle during the tip-in/out process

For a compound power split hybrid system, such as the Corun hybrid system (CHS), a frequently encountered problem is determining how to compensate for the inertia torque of the transmission via the torque distribution of the two motors. The equivalent inertia of the transmission is variable and depends on the angular acceleration. According to the traditional control scheme, the target torque of the motors is distributed by simplifying the output angular acceleration to 0. This simplification introduces deviations in the torque distribution, and it is difficult to guarantee the quality of the two control quantities simultaneously. Recent research has also focused only on the control quality of one of the outputs. To solve this problem, a direct MIMO control scheme is proposed in this paper that directly calculates the target torques of the two motors based on control deviations. A multivariable model predictive controller (MPC) was designed for the control of transient processes. The simulation results showed that the proposed control method can improve the control accuracy of two objectives significantly, and it has an excellent ability to reject torque disturbances.

Field Enhancing Model Predictive Direct Torque Control of Permanent Magnet Synchronous Machine

For the short-term high torque output, an improved model predictive direct torque control (MPDTC) method with field enhancing is proposed to increase torque. In order to avoid the possible loss of synchronism while increasing torque, the MPDTC method limits the load angle in the cost function. Under the constant load angle limitation, the improved method increases the torque output capability by increasing the magnetic field. This paper starts from the torque calculation, theoretically analyzes the torque-load angle characteristics, and illustrates the flux vector trajectory with the voltage limit circle and current limit circle. The proposed method maintains the dynamic and static performance of the traditional MPDTC method while ensuring the system stability. The experimental results show that the torque capacity of the proposed method has been improved, and it has stable extreme output torque. So, some applications, such as electric load simulators, can choose the motor with small capacity and small inertia, thereby weakening negative effects of the inertia torque.

English

This new study on effects of gyroscope demonstrates the action on the spinning disc that the eight interrelated inertial torques system generated by its rotating masses. The physics behind this inertial torques manifest the action of the resistance and precession torques, which physics are described and explained. The latest research on the gyroscopic properties revealed the deactivation of the inertial torques that contradicts the principles of classical mechanics. Practical tests of the blocking of the gyroscope motion around one axis displays the deactivation of inertial torques acting around the axis of the load torque. In this condition, the gyroscope with one side support turns down under the action of its weight and frictional forces produced by the action of the precession torque and weight of the movable components. The precession torque is presented by the change in the angular momentum, while other inertial torques is deactivated. These phenomena present the new unknown gyroscopic effect that needs a deep study and explanation. This work considers the attempt to describe the physics of the deactivation of the gyroscopic inertial torques around two axes and the action of the precession torque in a case of the gyroscope motion around one axis. Key words: Gyroscope theory, inertial torque, deactivation of inertial torques

Fixed-Time-Convergent Generalized Extended State Observer Based Motor Control Subject to Multiple Disturbances

Inertia load change, torque disturbance, and sophisticated mechanical nonlinearity impose great challenge on the high-precision control design of motor servo systems. To achieve better tracking and disturbance rejection performance, a practical control scheme, which combines a fixed-time-convergent generalized extended state observer (FGESO) with a fixed-time-convergent state feedback control law, is proposed in this article. First, an FGESO is designed to estimate the lumped disturbance and the fixed-time convergence of the estimation errors can be achieved. In the FGESO, there are three parameters and the correction term is selected as a continuous switching function of the output estimation error, which can facilitate the tuning process and greatly alleviate the chattering problem. Second, a control law based on the bilimit homogeneity technique is provided to regulate the tracking errors within a finite time independent of the initial condition. The fixed-time stability of the closed-loop system can be rigorously proved based on the Lyapunov theory. To facilitate the application of the proposed method, a practical two-step tuning procedure is established. Finally, extensive simulations and experiments are performed on a brushless direct current motor to validate the effectiveness and robustness of the proposed method.

Inertial torque on a small spheroid in a stationary uniform flow

How anisotropic particles rotate and orient in a flow depends on the hydrodynamic torque they experience. The torque acting on a small spheroid in a uniform flow is computed by numerically solving the Navier-Stokes equations. Overall, the numerical results provide a justification of recent theories for the orientation statistics of ice crystals settling in cold clouds.

The Influence of a Fluid Core and a Solid Inner Core on the Cassini State of Mercury

AbstractWe present a model of the Cassini state of Mercury that comprises an inner core, a fluid core, and a mantle. Our model includes inertial and gravitational torques between interior regions, and viscous and electromagnetic (EM) coupling at the boundaries of the fluid core. We show that the coupling between Mercury's interior regions is sufficiently strong that the obliquity of the mantle spin axis deviates from that of a rigid planet by no more than 0.01 arcmin. The mantle obliquity decreases with increasing inner core size, but the change between a large and no inner core is limited to 0.015 arcmin. EM coupling is stronger than viscous coupling at the inner core boundary and, if the core magnetic field strength is above 0.3 mT, locks the fluid and solid cores into a common precession motion. Because of the strong gravitational coupling between the mantle and inner core, the larger the inner core is, the more this coprecessing core is brought into an alignment with the mantle, and the more the obliquity of the polar moment of inertia approaches that expected for a rigid planet. The misalignment between the polar moment of inertia and mantle spin axis increases with inner core size, but is limited to 0.007 arcmin. Our results imply that the measured obliquities of the mantle spin axis and polar moment of inertia should coincide at the present‐day level of measurement errors, and cannot be distinguished from the obliquity of a rigid planet.

Interrelation of Precessed Motions of the Gyroscope

The fundamental principles of the gyroscope theory contain the system of the inertial torques generated by the rotating mass of the spinning disc that interrelated by the ratio of its angular velocities rotation around axes. The action of the centrifugal, common inertial Coriolis forces and the change in the angular momentum generate the system of inertial torques. These four dynamical components make up the system of the eight torques acting simultaneously on the spinning disc. They manifest their action in gyroscopic effects. The ratio of the precessed motions of the gyroscope presents one of the gyroscopic effects around axes of rotation. The known mathematical model for this ratio contains an error that was corrected in this work.

A Novel Moment of Inertia Identification Strategy for Permanent Magnet Motor System Based on Integral Chain Differentiator and Kalman Filter

In a motor control system, the parameters tuning of speed and position controller depend on the value of the moment of inertia. A new moment of inertia identification scheme for permanent magnet motor system was proposed in this paper. This is an extension of the existing acceleration deceleration methods, which solves the large moment of inertia identification error caused by variable angular acceleration, large calculation error of inertia torque, and large measurement noise in the acceleration process. Based on the fact that the angular acceleration is not constant and the sampling signal is noisy, the integral chain differentiator was used to calculate the instantaneous angular acceleration at any time and suppress the sampling signal noise at the same time. The error function with instantaneous angular acceleration and inertia torque as parameters was designed to estimate the moment of inertia. In order to calculate the inertia torque accurately, viscous friction torque was considered in the calculation of inertia torque, and Kalman filter was used to estimate the total load torque to solve the problem of under rank of motor motion equation. Simulation and experimental results showed that the proposed method could effectively identify the moment of inertia in both noisy and noiseless environments.

Effects of misfire on the dynamic behavior of gasoline Engine Crankshafts

Misfire faults caused by the malfunction of single cylinder increases the emission level and fuel consumption of internal combustion. So, the detection of misfire is required.In this paper, we studied the effect of misfire on the dynamic response of the crankshaft in order to propose a method based on the torsional vibration signal of crankshaft acceleration for misfire detection. For this, a torsional model of a four cylinder crankshaft excited by the acyclism phenomena is proposed. The external forces are the inertia and gas torque of each engine cylinder. The equations of motion are obtained by using Lagrange method and computed with the help of Newmark algorithm. Three kind of misfire faults of the first cylinder are modeled through the gas pressure variation inside this cylinder and induced in the excitation torques: missing combustion, pre-ignition and delayed ignition. After that, the vibration responses of the crankshaft is computed and processed in order to highlight the effect of misfire defects on the crankshaft vibration signals. In fact, appearance of sidebands around the acyclism frequency in the frequency domain allow detecting the misfire and the time acceleration signal allows identifying the kind of defect.

Balls rolling down a playground slide: What factors influence their motion?

Take a selection of balls and marbles along to a nearby playground slide and let students investigate factors that may influence how balls accelerate down an inclined plane. Students can make hypotheses in small groups, plan investigations to test multiple possible explanations and draw conclusions about the importance of different variables. The experiments illustrate the principle of equivalence between inertial and gravitational mass, as well as of the importance of mass distribution. Students can develop an intuitive feeling for these concepts even without dealing with the full mathematical treatment, which involves torque, angular momentum and moment of inertia, typically treated in high-school or introductory university physics courses. The paper discusses this investigation as part of a setup of teacher professional development events on a playground.