Abstract: A driving apparatus which drives an object along a guide surface in X and Y directions. The apparatus includes a first actuator which drives the object in the X direction, a second actuator which drives the object in the Y direction, and a controller which controls the first and second actuators. The first and second actuators each have a reaction force counter which moves upon receipt of a reaction force generated in driving the object. In moving the object standing at a first position to a second position and stopping the object, the controller controls the first and second actuators such that acceleration periods of the two coincide and deceleration periods of the two coincide. Also, the object moves on a straight line connecting the first position and the second position.

Abstract: A magnetic bearing system allows a movable body to be positioned to a point of substantial equilibrium in an axial direction after a system shutdown. A sensor measures the axial position of the movable body to produce an displacement output. That output is then adjusted to account for a sensor offset. The adjustment is stored and can be used to position the movable body during regular operation of the system or when the system reboots or restarts. The adjusted displacement output is converted into a force for positioning the movable body. The movable body may be a rotor in a heart pump apparatus.

Abstract: A guideless stage for aligning a wafer in a microlithography system is disclosed, and a reaction frame is disclosed which isolates both external vibrations as well as vibrations caused by reaction forces from an object stage. In the guideless stage an object stage is disclosed for movement in at least two directions and two separate and independently movable followers move and follow the object stage and cooperating linear force actuators are mounted on the object stage and the followers for positioning the object stage in the first and second directions. The reaction frame is mounted on a base structure independent of the base for the object stage so that the object stage is supported in space independent of the reaction frame. At least one follower is disclosed having a pair of arms which are respectively movable in a pair of parallel planes with the center of gravity of the object stage therebetween.

Abstract: An electric motor such as a driving source of an electric vehicle is controlled by the microcomputer 7. The microcomputer 7 calculates a target torque Req_trq according to a throttle opening degree ?, and outputting induction values (a current instruction value I and a angle instruction value ?) obtained referring to a map MP based on the target torque Req_trq (a motor rotational number Nm and a battery voltage Vb), the microcomputer 7 performs a torque control of an SR motor 3. The motor rotational number Nm detected from the SR motor 3 is passed through a band pass filter 51. Passing by the band pass filter 51, a signal data of the extracted 0.1-50 Hz is executed a PD calculation process 52, the calculated corrected amount PD_out is subtracted from the target torque Req_trq.

Abstract: An electric power steering apparatus for applying an assisting steering force to a steering mechanism of a vehicle by driving an electric motor according to a steering operation includes: an electric current command value calculation unit which calculates an electric current command value; a drive control unit which controls the drive of the electric motor based on the electric current command value; and a convergence control unit which determines a damping compensation value so that a quantity of steering operation is converged to a neutral point. The convergence control unit includes: a compensation electric current setting unit determines a basic damping compensation electric current value corresponding to the correction value of the target value, and a compensation electric current adjusting unit which adjusts the basic damping compensation electric current value based on the steering torque and the quantity of the steering operation, thereby calculating the damping compensation value.

Abstract: A full-closed control apparatus for performing velocity control based on a velocity signal of a motor and performing position control based on a position signal of a load driven by the motor, including: an equivalent rigid system velocity loop model; a band-pass filter; an amplitude adjuster; and a unit for inputting a velocity instruction of a velocity control loop into the equivalent rigid system velocity loop model, inputting a difference signal obtained by subtracting an output of the equivalent rigid system velocity loop model from a velocity signal of the load into the band-pass filter, inputting an output of the band-pass filter into the amplitude adjuster and outputting a signal obtained by adding an output of the amplitude adjuster to an output of a position controller, as a new velocity instruction.

Abstract: To provide a vibration-damping positioning controller capable of effecting stable positioning operation within a short period of time.

Abstract: The invention provides a synchronous motor sensorless controller which drives a synchronous motor without use of a rotational position sensor. The controller has a relative position counter 4 which acquires an estimated position of a magnetic pole from the position-and-speed estimation device simultaneously with resetting a summated value to zero when the reference position signal is input and which starts summation operation; and a speed instruction generator 3 having a position controller 29 which performs position control operation on the basis of a deviation between an instruction value pertaining to the amount of movement from the reference position and a summated value output as a relative position from the relative position counter, the generator outputting a speed instruction. The sensorless controller can position at a predetermined location a synchronous motor not having a position sensor.

Abstract: Control parameters are regulated without oscillating a servo control system. Respective control parameters P[p] (p=0, 1 - - - ), arranged in the order of gradually increasing a chance of oscillating the servo control system, are set sequentially starting with P[0], a torque command Tr or a fluctuation amount &sgr;, showing a variation in frequency component of vibration of a speed feedback amount &ohgr;, is determined for each of control parameters, and the servo control system is assumed to have reached an oscillation criticality when a fluctuation amount exceeds a specified value to thereby reset a control parameter set at that time to P[p−q] (q; natural number) or to P[0].

Abstract: An electromagnetic suspension system for a vehicle, comprises an electromagnetic actuator interposed between a sprung mass and an unsprung mass and disposed substantially in parallel with an spring element. An electric motor is provided for driving the electromagnetic actuator. A motor controller is configured to calculate a displacement input applied to the electromagnetic actuator and to control the electric motor in a manner that the electromagnetic actuator generates an optimum damping force corresponding to the displacement input. A motor control circuit is provided for the electric motor, through which the electric motor is connected to the motor controller. Additionally, an electrical damping element is electrically connected to the motor control circuit and in parallel with the electric motor to generate a damping force in a passive manner under a dynamic braking of the electric motor in response to the displacement input to the electromagnetic actuator from the unsprung mass.

Abstract: Damping of mechanical oscillation in a shaft that is provided by feedback wherein the output signals of multiple feedback devices are negatively coupled and added to a desired speed signal of a motor speed controller of the driving motor is disclosed. At least one sensor and/or measuring system can be provided for measuring an actual position value. The actual speed of the shaft can be determined by differentiation from the shaft position value measurements or by integration from shaft acceleration measurements. The measured or actual speed of the shaft can be supplied as an input signal to each feedback element. Each feedback element is specifically tuned to an oscillation frequency range of the shaft that is to be damped. The invention provides an easy and cost-effective way of damping mechanical oscillations that have limited frequency ranges.

Abstract: A full-closed control apparatus for performing velocity control based on a velocity signal of a motor and performing position control based on a position signal of a load driven by the motor, including: an equivalent rigid system velocity loop model; a band-pass filter; an amplitude adjuster; and a unit for inputting a velocity instruction of a velocity control loop into the equivalent rigid system velocity loop model, inputting a difference signal obtained by subtracting an output of the equivalent rigid system velocity loop model from a velocity signal of the load into the band-pass filter, inputting an output of the band-pass filter into the amplitude adjuster and outputting a signal obtained by adding an output of the amplitude adjuster to an output of a position controller, as a new velocity instruction.

Abstract: A system and method for controlling an active magnetic bearing assembly by varying the system control laws in a continuous non-linear fashion as a function of rotor rotational speed. The system control law variation is carried out in a continuous and optimal manner over the operating speed range of the rotor, and is not computationally intensive.

Abstract: An electric power steering apparatus for applying an assisting steering force to a steering mechanism of a vehicle by driving an electric motor according to a steering operation includes: an electric current command value calculation unit which calculates an electric current command value; a drive control unit which controls the drive of the electric motor based on the electric current command value; and a convergence control unit which determines a damping compensation value so that a quantity of steering operation is converged to a neutral point. The convergence control unit includes: a compensation electric current setting unit determines a basic damping compensation electric current value corresponding to the correction value of the target value, and a compensation electric current adjusting unit which adjusts the basic damping compensation electric current value based on the steering torque and the quantity of the steering operation, thereby calculating the damping compensation value.

Abstract: An open-loop system for synchronizing movement of a slide out room includes a pair of motors connected to extendable members which support the room during movement between an extended and a retracted position for driving the extendable members, a controller connected to the motors, and a plurality of switches connected to the controller for permitting operator control of the system. The controller provides synchronized output signals to the motors which have known output characteristics depending upon the motor inputs. The controller thus ensures the motors move substantially in unison without requiring feedback from the motors or the extendable members. The system may be initialized to establish stop positions of the extendable members which are stored in the controller.

Abstract: The invention relates to a numerical controlling unit that includes: a instructing part that provides a command acceleration for a servomotor, a parameter storing part that stores a threshold parameter about a load of the servomotor, and a load measuring part that measures the load of the servomotor. The load measured by the load measuring part and the threshold parameter are compared by a load comparing part, and an acceleration adjusting part changes the command acceleration for the servomotor based on a result compared by the load comparing part. A controlling part controls the servomotor based on the changed command acceleration. According to the invention, the command acceleration for the servomotor is suitably changed based on the result of comparing the load measured by the load measuring part and the threshold parameter. Thus, it can be prevented that the servomotor is subjected to an overload while using the maximum performance in feeding a work piece.

Abstract: A guided stage mechanism suitable for supporting a reticle in a photolithography machine includes a stage movable in the X-Y directions on a base. Laterally surrounding the stage is a rectangular window frame guide which is driven in the X-axis direction on two fixed guides by means of motor coils on the window frame guide co-operating with magnetic tracks fixed on the base. The stage is driven inside the window frame guide in the Y-axis direction by motor coils located on the stage co-operating with magnetic tracks located on the window frame guide. Forces from the drive motors of both the window frame guide and the stage are transmitted through the center of gravity of the stage, thereby eliminating unwanted moments of inertia. Additionally, reaction forces caused by the drive motors are isolated from the projection lens and the alignment portions of the photolithography machine.

Abstract: A control device and method is provided for controlling a control element by receiving a controller demand signal and a control element sensor signal, and processing the signals to determine if there is a change in the controller demand signal and/or a change in the control element sensor signal. A first dead band range and/or a second dead band range are determined based on the change in the controller demand signal and/or based on the change in the control element sensor signal. An error signal is calculated from the controller demand signal and the control element sensor signal, and a control signal for controlling the control element is generated based on the determination of the dead band ranges and whether the calculated error signal is outside of the first and/or second dead band ranges.

Abstract: An articulating probe head includes motors 12 and 18 for driving respective output shafts 14 and 20 about respective orthogonal axes z and x to move a stylus 22 over the surface of a workpiece under the control of a controller 26. At least one of the motors is inertia balanced by mounting the stator 32 of the motor on bearings 42 to allow it to rotate in opposition to the rotation of the rotor 34. Control of the speed of the spinning stator is achieved by connecting it to the winding assembly 46 of an additional “back-to-earth” motor 47 the magnet assembly 48 of which is connected to the housing. The motor 47 acts as a brake to prevent overspeeding of the rotatable stator, and can have power supplied to it to ensure that the stator does not slow down excessively when the main motor is running at constant angular velocity. Control of the power supply to the motors is achieved by the controller 26.

Abstract: In accordance with the present invention a scanning method for flat objects obtains reciprocating ballistic motion without any physical contact between the mutually moving parts, as contact can create particulate matter causing defects. The method ensures that the peak forces attained during scanning are minimized to prevent dislodgement of particulate material and excessive vibration. The method furthermore ensures that both surfaces of flat plate objects be scanned simultaneously.

Abstract: An energy absorbing filter for reducing mechanical oscillations in motor is disclosed. The energy absorbing filter places a virtual shunt across the motor windings so as to dissipate mechanical vibrations as resistive losses. This is accomplished by the placing of a large capacitance in parallel with the windings. The impedance of the filter and the windings combined is purely resistive. The motor may be any kind of motor including a 2-, 3-, or 5-phase hybrid step motor. The filter may be realized as an analog or digital filter, or may be a hybrid of the two. Additionally, the filter may be realized through hardware or through software in the form of a computer program.

Abstract: Conditions for permitting operation of vibration control are that; a stored charge of a battery 17 for an electric motor detected by storage state monitoring devices 15 and 24 is larger than a predetermined storage charge threshold, a vehicle's engine is idling, engine speed is within a prescribed range, and engine load is within a prescribed range. When all these conditions are satisfied, vibration damping control by a vibration damping control device is performed.

Abstract: With a simple operation of inputting the target movement amount for the stage through the input device as input data, an acceleration signal is output from the control device to the acceleration/deceleration device based on the input data, and then n×T seconds after the acceleration signal is output, a deceleration signal having the same waveform as that of the acceleration signal and an opposite direction thereto is output.

Abstract: The device for the generation of vibrations comprises an external casing provided with means of connection to a support structure and at least one mobile internal mass housed in the casing. The device is also provided with magnetic means of guidance of the mobile internal mass with respect to the casing; means of establishing the position and/or the motion of the same mobile mass with respect to the casing, and means of automatic control of the magnetic means of guidance. Furthermore, the mobile internal mass comprises at least one magnetically active element.

Abstract: A method and apparatus for essentially eliminating cyclic disturbances in a motor control system, the method including identifying frequencies of undesirable components in a feedback signal that exceed a threshold level and generating a combined signal including sine wave components corresponding to each of the identified frequencies, delaying the combined signal to generate a plurality of identical but phase shifted combined signals, weighting each one of the delayed signals as a function of the magnitude of an instantaneous corrected signal which is the difference between a velocity error signal and a compensation signal and adding each of the weighted signals to generate the compensation signal.

Abstract: A system and method for reducing reaction forces induced in a machine frame by an oscillating tool employs a counterforce assembly which is driven to move along linear slides mounted to the machine frame. The counterforce assembly is driven with a drive signal derived from two signals: a first signal which is proportional to the acceleration of the tool, and a second signal which is directly proportional to the velocity of the oscillating tool. By properly-adjusting the acceleration and velocity components of the drive signal, the magnitude of the reaction forces induced in the machine frame by the oscillating tool can be substantially reduced. The counterforce assembly preferably includes a centering means which prevents it from moving to either end of the slide. An accelerometer is preferably mounted to the machine frame to sense its vibration, with the accelerometer output used to adjust the counterforce assembly's drive electronics to reduce vibration to a minimum.

Abstract: A position controller for motors for increasing the position loop gain of a full-close control system without causing recurrence of vibration. The controller where a position signal representing the position of a movable table and outputted from straight-line motion position sensing means attached to a straight-line motion mechanism is used as a position feedback signal comprises differentiating means (2) for differentiating a straight-line motion position signal and outputting a straight-line motion speed signal, subtracting means (4) for calculating the difference between a speed command signal and the straight-line motion speed signal, integrating means (3) for integrating a difference signal outputted form the subtracting means, proportional gain means (1) for receiving the output signal from the integrating means, and adding means (19) for adding the output signal form the proportional gain means to the speed command signal and outputting a new speed command Vr.

Abstract: Acceleration/deceleration control is performed on the basis of a designated jerk control such that a maximum absolute value Jmax of jerk value, which is differential value of acceleration, is made not larger than a predetermined value when a commanded quantity of servomotor movement is smaller than a minimum quantity Smin of motor movement which is required to allow the movement of the servomotor to reach a predetermined maximum velocity Vmax and a predetermined maximum acceleration Amax.

Abstract: A wafer stage chamber assembly is provided to isolate semiconductor substrates, a wafer stage device, and the process of making semiconductor wafers from the atmosphere so that the resulted wafers have an improved quality and meet certain wafer manufacturing specifications. The wafer stage chamber assembly includes a wafer stage chamber for sealing a wafer stage device from the atmosphere outside the wafer stage chamber, and at least one loader port for loading and unloading substrates into the wafer stage chamber. The wafer stage chamber is constructed of a chamber frame to enclose the wafer stage device, and a plurality of chamber walls including a front panel having the at least one loader port for loading and unloading a plurality of semiconductor substrates into the wafer stage chamber. The wafer stage chamber assembly also includes a top wall and a base frame.

Abstract: A servo controller capable of driving a single movable member by two motors with high loop-gain setting to obtain a quick response. A servo controller includes two position controllers associated with respective motors and a damping controller. Each of the position controllers has a position control section to output a velocity command based on an identical position command from a host controller and a position feedback value from an associated position detector, a velocity control section to output a current command based on the velocity command and a velocity feedback value from an associated velocity detector, and a current control section to output a voltage command based on the current command and a current feedback value from an associated current detector. The damping controller outputs a current command correction value for compensating an interference between the two motors based on the velocity feedback values from the velocity detectors for the two motors.

Abstract: A machine includes an electric drive motor and at least one component carrying out a periodic motion. The machine is configured to control the drive motor in such a manner that it applies a predetermined torque to the machine.

Abstract: An oscillation isolator for supporting an oscillation isolation platform on a pedestal includes an active oscillation isolator having a displacement generating type actuator to reduce oscillation of the platform and a displacement adjuster provided between the active oscillation isolator and the platform or the pedestal for adjusting relative displacement between the active oscillation isolator and the platform or the pedestal. The displacement adjuster has a rigidity higher than that of the active oscillation isolator and is dynamically located in series between the active oscillation isolator and the platform or the pedestal.

Abstract: There is disclosed an apparatus for reducing motor driving noise, comprising: a selecting circuit for selecting and outputting a current increasing or reducing signal based on a commutation control signal; and a signal synthesizing circuit for synthesizing the current increasing or reducing signal selected by the selecting circuit with a current application control signal supplied to the power supply side switching element of at least a pair of switching elements.

Abstract: A controller for a machine such as a robot and a machine tool having an electric motor as a driving source of the machine, capable of suppressing a natural vibration of the machine and/or an attachment attached to the machine. A frequency or a cycle of the natural vibration of an end effector of the robot as the attachment or the machine itself is determined and a coefficient of a filter for suppressing an amplitude of the natural vibration is altered in accordance with the measured frequency or cycle of the natural vibration. In the case of suppressing a natural vibration of the end effector attached to the robot, frequencies or cycles of natural vibrations of various end effectors in accordance with an operation status of the end effector are determined and stored, and the coefficient of the filter is set in accordance with the stored frequency or cycle of the natural vibration in accordance with the end effector attached to the robot and the operation status.

Abstract: A method and apparatus are provided for modeling an electric motor. The method includes the steps of interpolating a flux density for each angular position within an air gap of the electric motor from a predetermined air gap and tooth magnetization magnetomotive force versus air gap flux density curve, decomposing the interpolated flux density into a set of harmonic components using a fast Fourier transform and determining a flux density error function from the decomposed set of harmonic components.

Abstract: A controller for an electronically commutated electrical machine receives a feedback signal indicative of a parameter which it is desired to minimize, e.g. torque ripple, current, voltage, vibration or acoustic noise. The controller computes the amplitude and phase of a set of harmonics in the parameter and sequentially injects harmonics of the correct amplitude and phase to minimize the parameter. An optimizing routine iterates through the set of harmonics to further reduce the parameter.

Abstract: The present a step controller includes a switching circuit having at least two outputting states, especially a three-level switch (DPS1) with negative feedback, and a PI or PID controller having an integrator (I1). The integrator is inactive during the positioning pulse of the three-level switch. The integrator (I1) is provided with a correcting element (CORR) which reduces the reset time (Tn) for a large input signal (xd). In this way, linear behavior of the step controller can be attained over the entire positioning range of a positioning element.

Abstract: When a drive unit which drives a reticle stage accelerates or decelerates it, the reaction experienced by this drive unit is discharged to a floor FD via an actuator, an attached member, and a reaction frame. Vibration generated in the reaction frame at this time is detected by an acceleration sensor. A vibration cancellation control section determines a direction and thrust for driving a movable section to which a weight is fixed in order to quell vibration of the reaction frame detected by the acceleration sensor, and emits a control signal to a driver.

Abstract: The present invention is a control method and numerical control for the vibration-reduced acceleration of a movable machine element of a numerically controlled industrial processing machine, in which a path of movement of the machine or machine element is broken down into directly successive interpolatable movement sections In the interpolation, resultant acceleration profiles which lie in a range close to a critical natural frequency of the machine or machine element are carried out with a reduced acceleration. By this method, intervention is made only in critical ranges of the acceleration profile, uncritical ranges remain uninfluenced, as a result of which drastic time losses during positioning can be avoided.

Abstract: A device and method for reducing vibrations of a structure along an axis of vibration propagation, in particular in a helicopter, wherein two vibrating members of masses m1 and m2 are located at the ends of a spring, the spring and/or the masses being so constructed that the resonance characteristics of the assembly may be variably adjusted within a range decisive for the reduction of vibrations of the structure. The phases of the movement of the two masses and of a central point of the spring connected to the structure are measured by accelerometers and the differences of phase angle compared to the base point are maintained at 90° by moving the masses using motors to bring about the necessary change in resonance of the assembly.

Abstract: The flux producing current limit of the motor control is adjusted to control the vibration of a motor. The flux producing current may be profiled in relation to the speed of the motor to compensate for excessive motor vibration.

Abstract: The invention is a low-cost stepper motor drive system comprising a microstepping motor and a logic circuit. The logic circuit includes two integrated circuits for controlling one or more phases of the microstepping motor. Each one of the integrated circuits is a motor driver capable of producing up to sixteen microsteps per full step. Further, each one of the integrated circuits takes a set of analog/digital bits and a phase bit as input. Additionally, within the logic circuit, there is included a microcontroller for controlling the microstepping motor. The microcontroller comprises six control bits, which direct the controller in outputting a set of step sequences to the integrated circuits.

Abstract: The present invention relates to a technique for outputting a vibration torque compensating current and removing a torque pulse generated at a footplate by using a detector for detecting a pulse rate generated at a sprocket and a device for detecting the magnitude of a pulse torque of an induction motor without changing the circumferential shape of the sprocket and the connecting structure of the footplate.

Abstract: A system for controlling the position of a rotating member suspended using a magnetic field includes at least one sensor that is operable to detect the position of the rotating member, the sensor further being operable to generate a position reference signal in response to the detected position. The system also includes a controller in communication with the at least one sensor and being operable to generate an actuator control signal in response to receiving the position reference signal. The controller is operable to introduce a phase lead in the actuator control signal in response to a rotational speed of the rotating member. The system further includes at least one actuator in communication with the controller that is operable to adjust the position of the rotating member in response to the actuator control signal by modifying characteristics of the magnetic field.

Abstract: A guided stage mechanism suitable for supporting a reticle in a photolithography machine includes a stage movable in the X-Y directions on a base. Laterally surrounding the stage is a rectangular window frame guide which is driven in the X-axis direction on two fixed guides by means of motor coils on the window frame guide co-operating with magnetic tracks fixed on the base. The stage is driven inside the window frame guide in the Y-axis direction by motor coils located on the stage co-operating with magnetic tracks located on the window frame guide. Forces from the drive motors of both the window frame guide and the stage are transmitted through the center of gravity of the stage, thereby eliminating unwanted moments of inertia. Additionally, reaction forces caused by the drive motors are isolated from the projection lens and the alignment portions of the photolithography machine.

Abstract: A control system for determining a control function for a control device on the basis of a transfer function of an object to be controlled and for adjusting an operation quantity of an object to be controlled in accordance with the determined control operation function, wherein an control function of a first control device is determined so that a closed-loop transfer function of a control system including the object to be controlled and the first control device coincides with a predetermined first transfer function, an control function of a second control device is determined, in a closed loop control system including the control system and the first control device, so that a transfer function from a disturbance applied to the object to be controlled to a state variable of a point at which the disturbance is applied to the object to be controlled, and a sum signal indicative of a sum of outputs of the first and second control devices is used as an operation quantity of the object to be controlled.

Abstract: A filter module inserted into a speed control loop to shorten the rise time of the loop. The filter parameters of the filters provided in the filter module and the controller parameters are calculated in such a way that instances of resonant rise. The amplification factors for the proportional controller branch and the integral controller branch are increased, which leads to a shorter rise time.

Abstract: An active attenuation system for a DC motor which yields global vibration reduction of slot or other motor induced tonals at the plate on which the motor is mounted without modifying the construction of the motor. The system comprises one or more vibration sensors, a signal synchronized to the slot rate or other motor induced tonal rate, an electronic adaptive controller and the means to supply the control signal into the motor field and/or armature current.

Abstract: An induction motor control system (10) for electric vehicles having a DC power supply (12), an inverter (14), an induction motor (16), and a clamping unit (26). The clamping unit (26) applies a clamping value iq_clamp to a real torque current command iq*. The clamping value iq_clamp is calculated in a maximum torque current calculation unit 28 and is based on predetermined maximum settings for the motor power Pmax and torque Tmax. The clamping value iq_clamp is applied such that the torque current command iq* cannot exceed the clamping value iq_clamp, whereby the induction motor produces 16 output power Pout and torque Tout that is always less than the predetermined maximum settings, Pmax and Tmax.

Abstract: A method for the excitation of the radial force and torque winding systems of electrical drives with integrated magnetic bearings. The drives comprise an electrical machine with torque and radial force windings which are introduced in the stator or rotor, a position and angle sensor system and analog or digital electronic circuitry for the control, regulation, monitoring and feeding of the machine. A model is used for setting the rotor position (36,37) and the rotational angle of the rotor (&phgr;) which describes the relationship between the forces acting radially and tangentially at the rotor or at the stator respectively and the loop currents, and indeed in such a manner that it takes into account the deviations from the sinusoidal form of the force components, which depend on the rotational angle of the rotor (&phgr;).