Showing papers on "Damping torque published in 2000"

Vibrations of a Taut Cable With an External Damper

Abstract: A solution is presented of the problem of vibrations of a taut cable equipped with a concentrated viscous damper. The solution is expressed in terms of damped complex-valued modes, leading to a transcendental equation for the complex eigenfrequencies. A simple iterative solution of the frequency equation for all complex eigenfrequencies is proposed. The damping ratio of the vibration modes, determined from the argument of the complex eigenfrequency, are typically determined to within one percent in two iterations. An accurate asymptotic approximation of the damping ratio of the lower modes is obtained. This formula permits explicit determination of the optimal location of the viscous damper, depending on its damping parameter.

Optimum geometry for torque ripple minimization of switched reluctance motors

Abstract: For switched reluctance motors, one of the major problems is torque ripple which causes increased undesirable acoustic noise and possibly speed ripple. This paper describes an approach to determine optimum magnetic circuit parameters to minimize low speed torque ripple for such motors. The prediction of torque ripple is based on a set of normalized permeance and force data obtained from numerical field solution for doubly-salient geometries. For that purpose a neural net is trained to extract the data needed to predict the torque produced by a given geometry and excitation at any position of teeth. Hence the static torque curve can be constructed and torque ripple can be found. The accuracy of the approach developed is illustrated by comparing measured and predicted torque for a switched reluctance motor. The optimum parameters for minimum torque ripple conditions are sought using the augmented Lagrangian method. The paper presents the optimization results, and then proceeds to determine the range of geometric parameters which keep the torque ripple within /spl plusmn/10 of the optimum value.

Performance of a semi-active damper for heavy vehicles

Abstract: This paper describes the development, modeling, and testing of a prototype, continuously variable semi-active damper for heavy vehicles. A simple proportional valve is used to generate the variable damping coefficient and the detrimental effects of the oil flow forces acting on the valve spool are studied. The force tracking performance of the damper is then examined under simple input conditions. The compliance of the hydraulic fluid is found to have a strong influence on the response of the damper. The performance of the prototype damper is investigated under realistic operating conditions using a Hardware-in-the-Loop (HiL) test rig, with a single wheel station vehicle model. The prototype damper displays a time lag of approximately 20 ms between the demanded and achieved damping force. The semi-active suspension is found to be most effective in reducing the vehicle body motion relative to the performance of an optimum passive suspension.

Apparatus and method for active transmission synchronization and shifting

Abstract: A propulsion system designed for hybrid vehicle's utilizing a first torque path from a coupled motor generator system and internal combustion engine through and automatically shifted manual transmission having a secondary torque path from a secondary torque source to the wheels. The system incorporates the high-efficiency of a manual transmission with the smoothness of the most advanced automatic transmissions by utilizing a second torque path to maintain driver requested torque during shifts. The system is also capable of performing shifts without opening the clutch by utilizing active synchronization of the input shaft RPM combined with the force control of the shifting actuator. This results in fast and smooth shifts that disengage and reengage without unpleasant torque pulsations.

Torque transmission between square wire and bracket as a function of measurement, form and hardness parameters.

Abstract: The aim of the study was to investigate the influence of cross section, edge geometry and structural hardness on torque transmission between square wire and bracket For this purpose, 5 different brands of stainless steel square wire in 3 dimensions (0016" x 0016", 0016" x 0022" and 0017" x 0025") were inserted into edgewise brackets with a slot size of 0018" and loaded with different torques (1 and 3 Ncm) The slot and wire geometries were analyzed by computer on ground specimens before and after loading In addition, the Vickers hardness and micro-hardness of the unstressed and stressed metal surfaces were determined While the slot size was very accurately maintained, the wire dimensions deviated downwards by an average of 10% Torque transmission led to notching and bending-up phenomena on the bracket slot flanks A torque loading of 3 Ncm increased the torque play of 0016" x 0022" wires by 36 degrees, and of 0017" x 0025" wires by 37 degrees In the case of 0016" x 0016" wires, an effective torque transmission was no longer possible The average Vickers hardness of the wires was 533 kp/mm2, and that of the brackets 145 kp/mm2 The micro-hardness in the deformation area of stressed internal slot walls increased with increasing load transmission from 204 to 338 kp/mm2 As a result of excessively small wire dimensions and plastic deformation of the brackets, a relatively large torque play occurs Deformation and notching in the area of the internal slot walls are inconsistent with demands for recycling brackets A standardization of bracket wire systems stating the actual torque play would be desirable

Torque control strategy for management of creep and grade hold torque in a wheeled vehicle whose powertrain includes a rotary electric machine

Abstract: A torque control strategy control for management of regenerative braking in a motor vehicle. A first processor ( 12 ) processes throttle request data ( 20 ) and torque modification data ( 40 ) from a second processor ( 14 ) to develop motor torque request data ( 28 ) for controlling rotary electric machine torque. The second processor processes brake request data ( 26 ), the throttle request data, and operating data from the at least one operating data source to develop friction brake torque data ( 30 ) for controlling friction brake torque applied to the vehicle and the torque modification data for the first processor. The two processors interact such that as long as the operating data from the at least one operating data source does not require that regenerative braking torque be limited, the torque modification data supplied to the first processor from the second processor equates to the brake torque request data, and the friction brake torque data does not cause the friction brakes to be applied, and when the operating data from the at least one operating data source calls for some limiting of the regenerative braking torque, the amount of limiting is subtracted from the torque modification data and the friction brake torque data equates to that amount of limiting for causing the friction brakes to be applied in that amount. At zero and near-zero speeds grade hold torque is calculated according to a formula and added to the friction torque.

Control and response characteristics of a magnetorheological fluid damper for passenger vehicles

Abstract: This paper presents control characteristics of a semi-active magneto-rheological (MR) fluid damper for a passenger vehicle. A cylindrical MR damper is devised and its governing equation is derived. After verifying that the damping force of the MR damper can be continuously tuned by the intensity of the magnetic field, PID controller is employed to achieve the desired damping force. The proposed MR damper is then applied to a full-car model and performance characteristics of the full-car such as vertical acceleration of the body are evaluated via hardware-in-the-loop-simulation (HILS).

Electric power steering controller and control method thereof

Abstract: An electric power steering controller including a motor for generating torque for assisting the steering torque of a driver to assist the steering force of a steering system. The controller includes a road reaction torque detector for detecting road reaction torque received by tires from the surface of a road, and a road detection torque addition control for controlling the torque of the motor based on the road reaction torque. The electric power steering controller enables the steering wheel to be returned to its starting point without adding torque in a direction in which the driver returns the steering wheel when the driver contgrols the steering wheel with the small road reaction torque of the tires, for example, when turning at an intersection at a low speed or when turning at a gently curved portion of a road at a high speed.

Control and Dynamics of Quarter-Car Models With Dual-Rate Damping

Abstract: Dynamics of a controlled quarter-car model is investigated. In this model, the damping coefficient of the car suspension is selected in a way that the resulting semiactive system approximates the performance of an active suspension system designed to produce sky-hook damping. According to this control strategy, the damping coefficient switches between two different values, leading to a piecewise linear dynamical model. For this model, the equation of motion is first presented in a general normalized form. Then, an appropriate methodology is applied for obtaining exact periodic motions for the case of forcing resulting from a road with harmonic profile. This methodology is based on employing the exact solution form within response intervals where the damping coefficient remains constant. The unknowns of the problem are then determined by imposing a set of periodicity and matching conditions. The stability analysis of the located motions is also performed by applying a method that is suitable for piecewise ...

Torque control strategy for management of rollback in a wheeled vehicle whose powertrain includes a rotary electric machine

Abstract: Requested brake torque and requested throttle torque are assigned opposite algebraic signs in both rollback and non-rollback states. In the non-rollback state, requested motor torque development includes a process step ( 206 ) in which requested brake torque and requested throttle torque are algebraically summed. In the rollback state, requested motor torque development includes a process step ( 218 ) in which requested throttle torque is substituted for the regeneration torque limit. In the rollback state, the difference between the requested throttle torque and the requested brake torque is compared with a zero vehicle speed regeneration torque limit ( 228 ) when the result of comparing the difference between requested throttle torque and the requested brake torque with the regeneration torque limit ( 222 ) discloses that the latter difference does not exceed the regeneration torque limit. The result is used to determine respective amounts of motor torque and friction brake torque ( 230, 232, 234, 236 ).

Model-based transmission upshift control with engine torque management

Abstract: An improved control for an automatic transmission upshift, wherein the engine output torque and on-coming clutch pressure are coordinated during the shift based on an inverse dynamic model of the transmission to achieve a desired output torque trajectory. The desired output torque trajectory is influenced by operator demand, and an initial value of the desired output torque trajectory is used along with the engine output torque to develop an input acceleration trajectory. The inverse dynamic model of the transmission is used (1) to determine an engine torque command that will achieve both the input acceleration trajectory and the desired output torque trajectory, and (2) to determine a feed-forward pressure command for the on-coming clutch that will produce the input acceleration trajectory, given the engine torque command. The desired output torque trajectory and the engine output torque are used to determine the expected input speed, and a feed-back control term based on the deviation of the measured input speed from the expected input speed is used to adjust the on-coming clutch pressure command to account for model errors. Finally, the closed-loop feedback error is used to enable adaptive correction of the feed-forward control so that the feed-forward clutch pressure more nearly produces the commanded input shaft acceleration.

Review of viscous damping in micromachined structures

Abstract: Damping in a vibratory mechanical device plays an important role in modulating the response of the system. It is of critical importance to understand the nature of damping and to be able to effectively control it for micro-machined devices such as sensors or actuators. For example, if damping is too low in a micro-machined lateral accelerometer, the severe degree of resonance of the accelerometer upon an impact of external force may produce such a large signal that cripples its control circuitry resulting in total system failure. High damping (near critical) is generally desired for accelerometers. As for yaw rate gyroscopic sensors, on the other hand, low damping is required in order to achieve sufficient sensitivity of the system under a given driving force and for certain types of applications. Therefore, in designing a MEMS device, the consideration of damping must be taken into account at the earliest stage. Micro-Electro-Mechanical-System (MEMS) devices are often operated in an isolated environment filled with nitrogen or other types of gas such that the gas functions as a working fluid and dissipates energy. A gas film between two closely spaced parallel plates oscillating in normal relative motion generates a force, due to compression and internal friction, which opposes the motion of the plates. The damping, related to energy loss of the system, due to such a force is referred to as squeeze film damping. In other cases, two closely spaced parallel plates oscillate in a direction parallel to each other, and the damping generated by a gas film in this situation is referred to as shear damping. Under the small motion assumption, both flow induced force is linearly proportional to the displacement and velocity of the moving plates. The coefficient of the velocity is the damping coefficient. The review will start with a discussion on effective viscosity coefficients that were used in some of the early work by T. Veijola et al., M. Andrews et al. and others. In general, the capping pressure for a micro-machined system is below or much below the atmospheric pressure. As pressure decreases, the mean free path of the gas molecules ( nitrogen for example) increases. When the mean free path is comparable to the air gap between two plates, one may no longer be able to treat the gas as continuum. Therefore, an effective viscosity coefficient is introduced such that governing equations of motion for fluid at relatively high pressures can still be used to treat fluid motion at low pressures where the mean free path is comparable or even larger than the air gap of the plates

Study on three-dimensional active cord mechanism: development of ACM-R2

Abstract: Describes the development of ACM-R2, which is new version of the active cord mechanism with 3D mobility. This ACM-R2 has installed a driving mechanism called "M-drive". This mechanism enables the ACM-R2 to acquire a high output/mass ratio and torque limiting joints, which works as a normal joint and deforms under excessive torque. It has also installed a new type of torque sensor, the "float differential torque sensor" on each joint. Additionally the ACM-R2 has also a self-contained structure with control computer and battery in the joint units. These specific driving mechanisms and the self-contained structure enable ACM-R2 to demonstrate new propulsion methods and motions combining the ability of a manipulator and a locomotor.

Method and arrangement in a hybrid vehicle for maximizing total torque output by minimizing differential torque capacities of the engine and generator

Abstract: Method for potentiating the utilizable torque output capacity of a hybrid electric vehicle is disclosed. The method includes controlling operation of an engine of a hybrid electric vehicle using a generator, the engine and generator being interconnected through a planetary gear system, the generator having approximately equal torque output capacity as the engine based on connective gear ratio selection. An engine controller is utilized for managing the engine's operation thereby permitting the engine to be operated at a torque output level substantially equal to the maximum torque output of the generator without a significant margin of excess control capacity of the generator over the engine. An overpower condition is detected in which the torque output of the engine is surpassing the maximum torque output of the generator. The engine is controlled to a torque output that is less than the maximum torque output of the generator.

Increased damping in cantilevered traffic signal structures

Abstract: Dynamic characteristics of a traffic signal structure were determined experimentally. Various strategies were investigated to provide additional damping. By decreasing the magnitude and the number of fatigue cycles caused by wind-induced oscillations, the service life is expected to be extended. Several damping devices were investigated and tested. The free-vibration response was used to determine the in- and out-of-plane damping of a full-scale pole with and without dampers. The dampers included elastomeric pads located within the joints, several impact dampers, tuning-mass systems, and a mechanical shock absorber (with a strut) positioned between the luminaire extension and the mast arm. An elastomeric pad located at the pole foundation connection and the shock absorber exhibited the most damping and were considered viable and practical options. The construction characteristics of each damper were noted.

Rotating vector methods for smooth torque control of a switched reluctance motor drive

Abstract: This paper has two primary contributions to switched reluctance motor (SRM) control: a systematic approach to smooth torque production and a high-performance technique for sensorless motion control. The systematic approach to smooth torque production is based on development of novel rotating spatial vectors methods that can be used to predict the torque produced in an arbitrary SRM. This analysis directly leads to explicit, insightful methods to provide smooth torque control of SRMs. The high-performance technique for sensorless motion control is based on a rotating vector method for high bandwidth, high resolution, position, and velocity estimation suitable for both precise torque and motion control. The sensorless control and smooth torque control methods are both verified experimentally.

Hybrid damping models using the Golla-Hughes-McTavish method with internally balanced model reduction and output feedback

Abstract: Viscoelastic materials (VEMs) are used to increase passive damping in structures. The damping capabilities of the VEM can be enhanced by attaching a constraining layer to the VEM. If this constraining layer is active, the treatment is called active constrained layer damping (ACLD). In the last few years, ACLD has proven to be superior in vibration control to active or passive damping. The active element allows for more effective vibration suppression than purely passive constrained layer damping. On the other hand, the VEM provides a fail-safe in case of breakdown of the active element that is not present for purely active control. It has been shown that the control effort needed to damp vibration using ACLD can be significantly higher than purely active control. In order to combine the inherent damping of passive control with the effectiveness of the active element, different variations of active, passive and hybrid damping are explored. Some of the variations included in this paper are passive constrained layer damping (PCLD) separate from the active element, but on the same side of beam and PCLD separate from the active element on the opposite side of the beam. The discretized system equations are obtained using the assumed modes method and Lagrange's equation. The damping is modeled using the Golla-Hughes-McTavish (GHM) method. This method adds `dissipation coordinates' to the structure in order to account for the damping present. These additional modes are eliminated using a reduction method, rendering the method more practical. A linear quadratic regulator and output feedback are used to actively control vibration.

Torque estimation method for an internal combustion engine

Abstract: A method is presented for correcting estimates of engine output torque and accessory load torque. Engine output torque estimates are corrected when the accessory is disengaged from the engine. Accessory load torque is learned, or corrected, when the accessory is engaged to the engine. In one example, these corrections are made when engine output torque is known to be substantially zero from torque converter speed ratio or from the timing of the overrunning clutch engagement. This information is then used to control engine output torque to improve drive feel and vehicle performance.

Adaptive off-state control method

Abstract: An Adaptive Off-state (AO) control method (55) for use in conjunction with a suspension system (10) including a controllable damper (22) interconnecting relatively moveable members (12, 14) to reduce the transmission of vibrational forces therebetween. Such suspension systems (10) are switchable between alternative on- and an off-state in accordance with a primary control method (53) and/or a secondary override control method (59). Sensors (48, 52) monitor the parameters of the suspension system (10), such as the displacement, velocity, and acceleration of the moveable members (12, 14). Damper command signals (107) are provided to the damper (22) in the on-state (116) to adjust the damping characteristics thereof. In the off state, the damping signal in conventional systems is approximately zero or a constant relatively low magnitude. According to the present adaptive off-state control method (55), the off-state damping signal (109) to the controllable damper (22) is modulated over time to make the off state damping a function of the system inputs. In a preferred embodiment, the modulation is a function of the real time or time-averaged input disturbances to the system (10). In an alternative embodiment, the modulation is derived from a user switch (57) that imparts a user variable Off-State Gain (OSG) to the off-state damping signal (109) based on operator perceived ride characteristics.

Damping force control device and method

Abstract: A damping force control device and method controls damping forces of dampers at locations of respective wheels. A first target damping force that inhibits vibrations of a vehicle body in the heave direction is calculated for each of the wheels, based on a single wheel model of the vehicle which employs the skyhook theory. A second target damping force that inhibits vibrations of the vehicle body in the pitch direction is calculated for each of the wheels, based on a model of front and rear wheels of the vehicle. A third target damping force that inhibits vibrations of the vehicle body in the roll direction is calculated for each of the wheels, based on a model of left and right wheels of the vehicle. One of the first through third target damping forces that has the greatest absolute value is selected for each of the wheels. The damping force exerted by the damper at the location of each wheel is set to the selected target damping force. Such a damping force control device inhibits the vehicle from making pitch or roll movements without damaging the control performance for attenuating vertical vibrations of the vehicle body.

Electromagnetic suspension control system

Abstract: PROBLEM TO BE SOLVED: To provide an electromagnetic suspension control system in which a satisfactory damping force characteristic can be secured SOLUTION: When an input voltage (an induced voltage of an electromagnetic damper 6) to a booster circuit 11 and, by extension, a stroke velocity are high, a duty ratio of switching of FET 18 is so determined for a damping force to be constant and FET 18 is switched in response to the determined duty ratio to obtain the damping force Even when the stoke velocity of the electromagnetic damper is large, the generating damping force can be restrained below the constant value, to develop into a state of over damping is restrained, and the satisfactory damping force characteristic can be attained In addition, by changing the duty ratio, an electric current run in the circuit can be regulated, the damping force characteristic can be changed over wider range, and, by extension, versatility can be advanced With an electric current in the circuit being reduced by adjustment, heat generation of the circuit can be restrained and over heating can be prevented

Torsional vibration damper for a torque transmitting apparatus

Abstract: A torque transmitting system including a torque converter or a fluid coupling. The system includes a torsional-vibration damper that is positioned within the housing of the fluid coupling and that serves to damp torsional vibrations. Several locations at which the torsional-vibration damper can be positioned are disclosed.

Damping of oscillations in wind turbines

Abstract: Damping of oscillations of the first bending mode of a wind turbine is performed means of one or more containers partly filled with a liquid for damping oscillations of the first natural bending frequency of the wind turbine. The damping means comprises a plurality of box shaped containers having a square cross section and being partly filled with liquid so as to provide a unidirectional damping with a logarithmic decrement of oscillations of the first natural bending frequency of the wind turbine of at least 4-8%. For off-shore wind turbines, the combined excitation of the wind and sea waves requires more damping, the damping is preferably equivalent to a logarithmic decrement of 10-15%. Furthermore, the invention relates to damping of oscillation of the second bending mode of a wind turbine and to the combined damping of oscillations of the first as well as the second bending mode of the wind turbine.

Apparatus and method for engine crankshaft torque ripple control in a hybrid electric vehicle

Abstract: A control system comprising a processor develops data controlling a combustion engine and a dynamoelectric machine arranged to interact with the engine to modify the torque output of the engine. An observer (10) develops observed data that comprises estimated engine speed, estimated crankangle, and estimated engine output torque represented as an estimated average value torque component on which is superimposed an estimated alternating polarity ripple torque component whose mean value over a time interval of interest is substantially zero. The estimated alternating polarity ripple torque component is an input to a torque controller (102) for the dynamoelectric machine which causes the machine to contribute, in real time, torque that substantially cancels the alternating polarity ripple torque component in the crankshaft torque.

Experimental measurements of actively controlled bearing damping with an electrorheological fluid

Abstract: Selection criteria and design evaluations of several types of bearing dampers with active control for application to aircraft engines were described in a companion paper. A disk type electrorheological (ER) damper was chosen for further study and testing. The results of the tests and the final conclusions of the study are described in this paper. Experimental results including stiffness and damping coefficients are presented for the ER bearing damper with two types of ER fluid, 350 CS and 10 CS (centistokes) viscosity. The vibration attenuation performance of the ER damper was measured on a rotordynamic test rig in the form of free vibration decay, rotor orbits, and runup unbalance responses. The results show that the ER fluid with lower viscosity has the better characteristics for rotordynamic applications. It was found that ER fluids produce both Coulomb and viscous damping. If only the damping is considered, the Coulomb type is less desirable, but with active control it can also achieve control of rotor stiffness. A feedback control system was developed and applied to the ER damper with the objective of improving the overall rotordynamic performance of the rotor bearing system, considering both vibration amplitudes and dynamic bearing forces. A bang-bang (on and off) simple control logic was found to work better in practice than more sophisticated schemes. The measured runup response of the rotor-bearing system with this control approximated the desired vibration response curves fairly well. The tests highlighted some of the practical considerations that would be important for aircraft engine applications, such as the ER fluid limitations, the electrical power supply requirements, the electrical insulation requirements, the nonlinear relationship between the voltage and the damping, and the relative benefits of active control. It is concluded that active control of bearing damping is probably not a practical improvement over the passive squeeze film dampers currently used in most aircraft gas turbine engines.

Smart Fluid Damping: Shaping the Force/Velocity Response through Feedback Control

Abstract: It is now well known that smart fluids [electrorheological (ER) and magnetorheological (MR)] can form the basis of controllable vibration damping devices. With both types of fluid, however, the for...

Direct Torque Control of induction motor with reduction of torque ripple

Abstract: It is widely known that Direct Torque Control (DTC) has fast dynamic torque response. It originates in the fact that torque and flux is directly controlled by instantaneous space voltage vector unlike Field Oriented Control (FOC). For the reason, Direct Torque Control gradually has been used in the field requiring fast response since its introduction in the mid-1980's. In spite of these merits, Direct Torque Control has several problems. These problems are : (1) the variation of the switching frequency by hysteresis band and speed; (2) the increase of the torque ripple in the low speed region; (3) the short control period (25 /spl mu/s) for the good performances etc. To solve the problems of Direct Torque Control, several studies were carried out. This paper improves one of the drawbacks of Direct Torque Control, torque ripple, with the constant switching frequency. In some papers it was tried to improve the drawback, but some papers are very complicated and didn't show large improvement. Their methods even resulted in losing the merits of Direct Torque Control. In this paper Direct Torque Control method is performed with constant switching frequency. So this scheme is easy to be realized with digital signal processor and also minimizes torque ripple.

Model-based engine torque control for power-on downshifting in an automatic transmission

Abstract: An improved engine torque control for an automatic transmission power-on downshift, wherein a dynamic model of the transmission is used to schedule both shift progression and engine torque reduction based on a desired trajectory of the transmission input shaft during the shift and the driver torque demand. The shift is initiated with the off-going clutch by using the dynamic model to conform the input speed to the desired trajectory, and the torque reduction is initiated based on an estimate of the time to synchronization relative to an expected control delay so that the torque reduction occurs when the input speed reaches synchronization. An appropriate torque reduction amount is calibrated for a specified driver torque demand, and in operation, the amount of torque reduction for a given shift is determined based on the current driver torque demand and a detected deviation of the desired trajectory from a nominal trajectory corresponding to the specified driver torque demand. Aberrant conditions, including failure of the input speed to reach synchronization and input speed flaring are detected and used to modify the engine torque control so that the shift is completed in a timely manner. Using the dynamic model to scheduling the torque control achieves more consistent shift feel and improved adaptability to different powertrain and vehicle-type configurations, and reduces the number of calibrated parameters requiring adaptive correction.