Showing papers on "Damping torque published in 1998"

Hydrodynamic torque converter

Abstract: The invention relates to a hydrodynamic torque converter having an impeller wheel, a turbine wheel and an oscillation damper which is accommodated in the converter housing, and a converter lockup clutch. Two damper stages are arranged here as a serial damper between the output hub of the torque converter and the converter lockup clutch, and a damper stage is arranged between the turbine wheel and the output hub. In order to improve the damping properties, a rotary oscillation absorber is additionally provided which is arranged between the dampers and is also connected to the turbine wheel in a rotationally fixed fashion.

Zero-speed tacholess IM torque control: simply a matter of stator voltage integration

Abstract: Most industry experts agree that the next generation of commercial drives will include some sort of sensorless torque control. Achieving a modest level of control in the very-low-speed range greatly increases the competitive value of the drive and expands its range of applications. After reviewing many of the previously presented sensorless control methods, this paper shows that the simple method of stator-flux orientation can provide zero-speed torque control equally as well as more complex approaches, which rely on elaborate mathematical models to improve the operating range. This paper experimentally demonstrates that, by using only a slight amount of low-pass filtering in the integration of the stator voltage, a reasonable flux estimate can be obtained for stator-flux-field-oriented torque control. With this simple method, adequate torque control has been demonstrated over a wide range of speed and load conditions, and even at zero rotor speed with moderate or heavy load torque.

Squeeze film damping effect on the dynamic response of a MEMS torsion mirror

Abstract: This paper presents analytical solutions for the effect of squeeze film damping on a MEMS torsion mirror. Both the Fourier series solution and the double sine series solution are derived for the linearized Reynold equation which is obtained under the assumption of small displacements. Analytical formulae for the squeeze film pressure variation and the squeeze film damping torque on the torsion mirror are derived. They are functions of the rotation angle and the angular velocity of the mirror. On the other hand, to verify the analytical modeling, the implicit finite difference method is applied to solve the nonlinear isothermal Reynold equation, and thus numerically determine the squeeze film damping torque on the mirror. The damping torques based on both the analytical modeling and the numerical modeling are then used in the equation of motion of the torsion mirror which is solved by the Runge-Kutta numerical method. We find that the dynamic angular response of the mirror based on the analytical damping model matches very well with that based on the numerical damping model. We also perform experimental measurements and obtain results which are consistent with those obtained from the analytical and numerical damping models. Although the analytical damping model is derived under the assumption of harmonic response of the torsion mirror, it is shown that with the air spring effect neglected, this damping model is still valid for the case of nonharmonic response. The dependence of the damping torque on the ambient pressure is also considered and found to be insignificant in a certain regime of the ambient pressure. Finally, the convergence of the series solutions is discussed, and an approximate one term formula is presented for the squeeze film damping torque on the torsion mirror.

Stabilization of a rotating body beam without damping

Abstract: This paper deals with the stabilization of a rotating body-beam system with torque control. The system we consider is the one studied by Baillieul and Levi (1987). Xu and Baillieul proved (1993) that, for any constant angular velocity smaller than a critical one, this system can be stabilized by means of a feedback torque control law if there is damping. We prove that this result also holds if there is no damping.

A unified model for the analysis of FACTS devices in damping power system oscillations. II. Multi-machine power systems

Abstract: This paper establishes a unified model of a multi-machine power system installed with three types of FACTS-based stabilizer, which is an extension of the work presented in part I of this paper. The application of the unified model is demonstrated by the damping torque analysis of multi-machine power systems, the conclusion of which is that the damping function of FACTS-based stabilizers can be interpreted as an addition of damping torque on every generator in the system. Three indices are proposed for the selection of the best installing location of FACTS-based stabilizers in multi-machine power systems, the use of which depends on the extent of available system information.

Optimized torque control of switched reluctance motor at all operational regimes using neural network

Abstract: Switched reluctance motor (SRM) optimal control parameters, which maximize torque per ampere, are calculated using a dynamic SRM model. In order to include the effect of the magnetic nonlinearity, static torque and flux-linkage data are used in the dynamic model. The static data are generated experimentally. To recreate these control parameters, online, artificial neural networks are used. Two separate networks are trained. One is trained with the low-speed control parameters for torque control at low speed, while the other is trained with the high-speed control parameters for torque control at high speed. The speed at which the SRM makes a transition from chopping control to single-pulse operation (i.e., low-speed to high-speed operation), commonly referred to as base speed, is torque (current) dependent. A small table is maintained in the controller to identify the base speed for different torque demands. When the motor exceeds the base speed for a certain torque demand, the controller switches from the low-speed neural network to the high-speed neural network and vice versa. It is also shown that the SRM is capable of producing an extended constant-horsepower operation with this optimal control. The power factor (the energy ratio) is shown to improve in this extended speed constant-horsepower range. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed control scheme.

Control apparatus and method for internal combustion engine

Abstract: In a control apparatus and method for a vehicular internal combustion engine, an accelerator operating variable detector is provided for detecting an operating variable of an accelerator operated by a driver, a revolution speed detector is provided for detecting a revolution speed of the engine, a driver demand torque calculator is provided for calculating an engine torque demanded by the vehicle driver on the basis of the detected operating variable of the accelerator and the detected revolution speed as a driver's demand torque. An external demand torque calculator is provided for calculating a correction variable for the engine torque demanded from an external load to the engine as an external demand torque, a relatively low response demand torque calculator is provided for calculating a relatively low response demand torque on the basis of at least one of the driver's demand torque and the external demand torque, a relatively high response demand torque calculator is provided for calculating a relatively high response demand torque on the basis of at least one of the driver's demand torque and the external demand torque. A first torque operator is provided for operating at least one object to be controlled in a relatively low response type so as to realize the calculated relatively low response demand torque, and a second torque operator is provided for operating at least one object to be controlled in a relatively high response type so as to realize the calculated relatively high response demand torque.

Control of robot arms using joint torque sensors

Abstract: Describes a basic study of vibration control, disturbance rejection, and friction compensation in robots with flexible drive systems. First, the system gain characteristic at the antiresonance frequency is introduced to evaluate the vibratory behavior of the control system. Secondly, joint torque negative feedback is discussed. While it is shown that joint torque negative feedback has a good effect on vibration suppression, the property of disturbance rejection is easily deteriorated when a high-gain joint torque feedback is used. Based on the assignment of pole-distribution, the relationships between vibration suppression and disturbance rejection are analyzed. Thirdly, a feedforward compensation control based on a friction observer is proposed. It is shown that the tracking error is effectively decreased by this friction compensation.

Helicopter Blade Response and Aeromechanical Stability with a Magnetorheological Fluid Based Lag Damper

Abstract: This paper explores the feasibility of using Magnetorheological (MR) fluid-based dampers for lag damping augmentation in helicopters. An MR damper model is integrated with a rotor aeromechanical model. Two different control schemes are presented-namely the On-Off scheme and the Feedback Linearization scheme. In the On-Off scheme, two criteria are used to obtain equivalent linear damping for the nonlinear MR damper as a function of the size of perturbation and the applied field. The Feedback Linearization scheme uses a feedback controller to linearize the force output of the MR damper. The two control schemes are compared for lag transient response in ground resonance and their ability to reduce periodic damper loads in forward flight. It is shown that an MR damper of a size comparable to an elastomeric damper can provide sufficient damping for ground resonance stabilization and can significantly reduce periodic damper loads with ajudicious choice of operation scheme.

Flux and torque control of switched reluctance machines

Abstract: The theory and implementation of a flux-linkage controller applied to a switched reluctance machine drive are described. Analysis of the simplified discrete time load model shows that a simple flux-linkage controller can produce a ‘dead-beat’ system response. Comparison of the response from a discrete time PID current controller, hysteresis current controller and the new flux-linkage controller, show that the flux controller has a much improved response. The experimental controller is used to control an IGBT converter, driving a commercial 7.5 kW switched reluctance motor. A method of constant torque operation is introduced. This takes account of limitations imposed by the finite DC-link voltage and rotor speed when calculating the reference values. The method is based on ‘flux ramps’, where the ramps are chosen to give constant shaft torque, and remain within the capabilities of the power converter. Correct selection of the flux ramps allows constant torque operation to be achieved over a wide speed and torque range. Measured results for the experimental drive demonstrate the low torque ripple achieved for motoring and generating operation over a range of speed and torque values.

Torque control device for hydraulic pump of hydraulic construction equipment

Abstract: A torque control device for hydraulic pumps of hydraulic construction equipments, in which signals from sensors (75-82) are inputted when environmental change reduces an output of an engine, correction gain calculating units (70m-70u) and a torque correction value calculating unit (70v) estimate reduction in engine output as a torque correction value (ΔTFL), and a speed sensing torque deviation correction unit (70i) subtracts the torque correction value (ΔTFL) from a speed sensing torque deviation (ΔTI) and adds to a pump base torque (TRO) the thus subtracted torque deviation (ΔTNL) to find an absorption torque (TR1) (target maximum absorption torque) and output a signal to a solenoid control valve (32). The solenoid control valve (32) controls a servo valve (22) for total horse power control to control the maximum absorption torques for hydraulic pumps (1, 2). Accordingly, even when a prime mover output decreases, it is possible to minimize reduction in the number of revolutions of the prime mover during high loading.

Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems

Abstract: A harmonic drive is a compact, lightweight, and high-ratio torque transmission device which is used in many electrically actuated robot manipulators. In this paper a built-in torque sensor for harmonic-drive systems is examined in detail. The method proposed by Hashimoto, in which strain gauges are directly mounted on the flexspline, is employed and improved in this paper. To minimize sensing inaccuracy, four Rosette strain gauges are used employing an accurate positioning method. To cancel the torque ripples, the oscillation observed on the measured torque and caused mainly by gear teeth meshing, Kalman filter estimation is used. A simple fourth-order harmonic oscillator proved to accurately model the torque ripples. Moreover, the error model is extended to incorporate any misalignment torque. By on-line implementation of the Kalman filter, it has been shown that this method is a fast and accurate way to filter torque ripples and misalignment torque. Hence, the intelligent built-in torque sensor is a viable and economical way to measure the harmonic-drive transmitted torque and to employ that for torque feedback strategies.

A method of controlling a torque ripple of a motor having interior permanent magnets and a controller using the same method

Abstract: Torque ripples of a motor having interior permanent magnets can be reduced through the following method and the torque ripple controller using the same method: first, drive the motor having a plurality of phase windings and interior permanent magnets with a basic current supply circuit which outputs a basic current having a predetermined waveform, then store torque ripple waves produced in the running motor or obtained through a numerical analysis into a torque-ripple-wave-memory, next, compensate the torque ripple wave tapped off from the memory according to a prepared torque ripple compensation pattern and transform it to a torque compensation waveform with a torque-compensation-waveform-producing-circuit, further, multiply the torque compensation waveform tapped off from the waveform producing circuit by the basic current with a multiplier to output a torque ripple control current, and, supply the torque ripple control current to the plurality of phase windings shifting a phase by a predetermined electrical angle sequentially.

Steering control system for controlling torque steer

Abstract: In a steering control system for controlling torque steer in a vehicle equipped with an electric power steering device and a torque split arrangement for individually controlling traction and/or braking force of right and left wheels, a difference in traction and/or braking force between the right and left wheels which may be produced by the torque split arrangement may give rise to torque steer depending on the geometry of the wheel suspension system of the vehicle. The control unit for the electric power steering device additionally receives an additional signal for providing an additional steering torque which is required for canceling the torque steer. Thus, the torque steer can be eliminated both economically and reliably without requiring to modify the wheel suspension system.

Drive train controller for a motor vehicle

Abstract: The drive train controller is used to calculate the position of the accelerator pedal which is interpreted as the wheel torque or transmission output torque desired by the driver, in order to calculate setpoint values for the torque to be output by the drive train. It contains a control circuit in which the desired wheel torque is evaluated, together with further operating parameters of the motor vehicle, in a fuzzy system. It outputs an output signal by which the wheel torque to be exerted on the roadway by the wheels of a motor vehicle is defined.

A study of frequency responses of generator electrical torques for power system stabilizer design

Abstract: Frequency response methods based on the concept of damping torque enhancement have been successfully used in the design of practical power system stabilizers. Central to this approach is the calculation of the frequency response from the automatic voltage regulator input to the electrical torque of a generator without the effect of rotor angle feedback. This paper carries out a study to deepen the understanding of certain important properties of the frequency response. It is shown that the frequency response of a generator can be considered as having two components. One component, which depends only on the associated generator, is very significant and has a great effect on the overall frequency response; it has the important property that its shape is fixed independent of the operating condition of the associated generator. The other component depends on the associated generator as well as on the external system. However, this component is found to be not much affected by the dynamics of generators in the external system because of the diagonal dominance of the reduced admittance matrix of the modified network with generators lumped into it as dynamic admittances.

The Torque on the Input Shaft of an Axial-Piston Swash-Plate Type Hydrostatic Pump

Abstract: Traditionally, the theoretical torque on the input shaft of a hydrostatic pump has been determined using a macroscopic power-in, power-out approach that neglects the time-varying aspects of this quantity and the compressibility of the hydraulic fluid within the circuit. In contrast to the traditional approach, this research analyzes and sums the basic forces within the machine to compute the instantaneous torque exerted on the shaft. It is shown that the instantaneous torque repeatedly varies by 1.5 percent of its maximum value and that resonant frequencies of the pump occur at even multiples of the piston-pass frequency. Furthermore, an integral average of the instantaneous torque is performed and shown to deviate by a maximum of 3 percent from the traditional method of computing this quantity.

Design of a rule-based controller for STATCOM

Abstract: A /spl plusmn/20 MVAr STATCOM (static synchronous compensator) using GTO technology was commissioned in China in 1998 The STATCOM is designed to supply fast voltage control and to enhance the damping of inter-area electromechanical oscillations of the system In this paper, by investigating the added synchronizing and damping torque induced by STATCOM, the conflicts between these control objectives are analyzed and the limitations or even invalidity of the fixed-parameters damping controller for certain system parameters and load conditions is discussed A rule-based controller, which employs bang-bang, fuzzy logic or fixed-parameter PI control strategy according to the operation state of the system, is designed The advantages of the proposed controller over the fixed-parameter PI controller are demonstrated by nonlinear digital simulations

Damping system having separately adjustable damping circuits

Abstract: An adjustable fluid damping system (24) for use in a suspension system that undergoes compression and rebound. The fluid damping system (24) permits independent adjustment of compression and rebound damping by providing separate compression and rebound damping circuits. Each circuit has an inlet (42, 52) through which damping fluid flows during damping, and an adjuster that adjusts the degree to which the inlet is open and hence damping through that flow path. The compression and adjusters are selectively and independently coupled to the same adjuster rod (92) via respective compression and rebound couplers (94, 96). The adjuster rod (92) can be coupled to only one of the couplers (94, 96) at a time. Rotation of the adjuster rod (92) by means of an adjuster knob (62), which can be pulled outward or pushed inward to engage one of the compression and rebound couplers (94, 96), causes rotation of the coupler coupled thereto and axial movement of the respective adjuster to modify damping though the associated damping circuit.

Control apparatus and method for powertrain of a vehicle

Abstract: A control apparatus and method for a powertrain of a vehicle provided with a drive unit which has the powertrain including an engine or an electric motor and an automatic transmission, and a driving shaft. The control apparatus is provided with first torque estimating means for obtaining a first estimated driving shaft torque, second torque estimating unit for obtaining a second estimated driving shaft torque used to correct said first estimated driving shaft torque, comparison means for comparing said first estimated driving shaft torque with said second estimated driving shaft torque, and driving shaft torque calculating means for calculating a driving shaft torque on the basis of the result of the comparison.

Method for determining the installed torque in a screw joint at impulse tightening and a torque impulse tool for tightening a screw joint to a predetermined torque level

Abstract: A basic method for determining the installed torque in a screw joint which is being tightened by a series of repeated torque impulses, wherein the rotational movement of the screw joint is detected during each impulse, the point in which the screw joint ceases to rotate is detected, and the actually applied torque is indicated the very instance the screw joint ceases to rotate. In a tightening process control application of the above described basic method, the per impulse increasing value of the installed torque is compared to a predetermined target value in a way known per so, and the tightening process is interrupted as the target value is reached. In a tightening process quality check application of the above described basic method, the accomplished angular displacements of the joint at repeated impulses are indicated and added, and high and low limit values for the final installed torque and the total angle of rotation are provided and compared to the actually obtained values. A torque impulse delivering power tool comprising an impulse generator (12) with an output shaft (13) having a torque transducer (23) and a rotation detecting device (24) both connected to a process control unit (33) in which a device is arranged to provide a torque target value and a comparating circuit is provided to compare the actual value of the installed torque with the target value and to initiate shut-off of the power supply to the power tool as the target value is reached.

Speed control of 2-inertia system with gear backlash using gear torque compensator

Abstract: In this paper, a new speed control method for 2-inertia system with gear backlash is proposed, which uses gear torque compensator. This compensator consists of two elements: the gear torque compensator and the feedback gain. The gear torque compensator consists of the gear torque observer and a gain; it has the characteristics of the motor torque command and speed of a 1-inertia system. However, using only the compensator has a bad effect on the vibration suppression caused by the torsional shaft. Therefore, we introduce the feedback gain and adjust it for vibration suppression. The combination of this method with common PID controller shows good performances in vibration suppression and disturbance rejection, both in the simulations and experiments.

Hybrid isolator and structural control actuator strut

Abstract: A vibration damping and isolation apparatus (10) including a passive damping mechanism (28) and an active enhancement mechanism (66). The passive damping mechanism operates to dissipate vibratory and shock forces applied to the vibration damping and isolation apparatus. The passive damping mechanism includes first and second spaced damping elements (30, 32). A first resilient structure (42) connects the first damping element to the second damping element to define a primary fluid chamber (37) between the first and second damping elements. The passive damping mechanism further includes a second resilient structure (50) that defines a secondary fluid chamber (56) which is in fluid communication with the primary fluid chamber via a fluid flow orifice (58). A fluid fills the primary fluid chamber, the secondary fluid chamber and the fluid flow orifice. The active enhancement mechanism includes a system for sensing changes in fluid pressure, loads or other parameters of the passive damping mechanism as a result of the forces applied to the vibration damping and isolation apparatus. An actuator system (67) of the active enhancement mechanism (66) is coupled to the sensing system and acts on the passive damping mechanism, to change the fluid pressure within the passive damping mechanism in response to the sensing system commands. By actively changing the fluid pressure within the passive damping mechanism in response to forces, the active enhancement mechanism enhances the vibratory and shock dissipation of the passive damping mechanism and can actively change the stroke of the apparatus or force exerted by the apparatus.

Active damping of engine speed oscillations based on learning control

Abstract: We present a learning control scheme for active damping of engine crankshaft oscillations using a supplemental torque source. The scheme comprises a linear feedback controller and a learning feedforward term which predicts the engine crankshaft torque. The proposed scheme is computationally efficient and it does not use an acceleration signal in the learning procedure.

Lock-up control device

Abstract: A lock-up control device is provided to control engaging force of a lock-up clutch, which shares engine output with a torque converter to transmit it toward an input shaft of a transmission. Herein, input shaft torque is estimated based on engine speed and engine intake negative pressure, while engine torque is estimated based on engine speed and throttle opening. A weight coefficient is produced based on an amount of variations of the engine torque when the amount of variations is greater than a prescribed value. Then, weighted mean engine torque is calculated by the input shaft torque and engine torque in accordance with the weight coefficient. Thus, the lock-up control device controls the lock-up clutch based on the weighted mean engine torque in such a way that the engaging force of the lock-up clutch is increased in response to the rise timing of the weighted mean engine torque. For example, the weight coefficient is determined in such a way that the engine torque is given high distributed weight in the weighted mean engine torque as compared with the input shaft torque. Thus, it is possible to increase the engaging force of the lock-up clutch promptly in response to the rise mode of the real engine torque, by which it is possible to avoid occurrence of control delay in control of the lock-up clutch.

Powertrain control device

Abstract: The object of this invention is to reduce shift shocks by controlling the driving torque during gear shift changing so that the driving torque is represented by a smooth, ideal waveform. The driving torque calculating means estimates the output shaft torque of the automatic transmission from the engine torque characteristic or torque converter characteristic and, based on the estimated driving torque, generate a targeted torque pattern during gear shift changing. The engine torque control value calculating means calculates the control value for controlling the engine output torque, i.e., an ignition timing correction value Δθig, so as to eliminate the deviation between the targeted torque and the driving torque estimated by the driving torque calculating means. This ignition timing correction approximates the driving torque to the smooth targeted torque. This configuration realizes the object mentioned above.

Friction hinge with detent capability

Abstract: The present invention provides a small, cylindrical hinge, or pivoting pin (5), which can be configured to produce various profiles of torque versus angle. The desired profile of torque versus angle is achieved by the shapes of the hinge shaft and the spring plates (9) of the hinge. Detents at one or more angular positions can be achieved, with or without frictional damping torque at other angles. The friction of our hinge is produced symmetrically about the hinge axis, eliminating the problems associated with asymmetric construction.