Abstract: An apparatus and method for detecting rotational vibration applied to a disc drive having an actuator supporting a head adjacent a rotatable disc. A spindle motor has a set of driver coils which rotate the disc through electrical commutation, and a set of velocity sense coils which sense the rotational velocity of the motor in relation to voltages established across the sense coils. Rotational vibration is detected in relation to changes in the rotational velocity of the disc. A data transfer operation between the disc and a host device is interrupted when the magnitude of the rotational vibration exceeds an acceptable level. A servo circuit compensates for the application of rotational vibration to the disc drive by adjusting current applied to the actuator in relation to the changes in the rotational velocity of the disc.

Abstract: A damper device has a magnet and at least two yokes facing the magnet across gaps. The magnet and the two yokes jointly provide a magnetic circuit such that a magnetic flux flowing from a first magnetic pole of the magnet is divided across one of the gaps into magnetic fluxes which flow into entrance sides of the yokes and back from exit sides of the yokes across another of the gaps into a second magnetic pole of the magnet. The two yokes are mechanically connected rigidly to each other, and a spring means elastically holds the one of the gaps between the first magnetic pole and the entrance sides of the yokes. One of the magnet and the yokes is adapted to be connected to a vibratable member. When the gaps are differentially varied in length by vibration of the vibratable member, the divided magnetic fluxes are changed to generate eddy currents in the yokes and the magnetic poles.

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 disk drive system includes a servo system for driving mechanical parts, including a read/write head, to a desired track on a disk. The mechanical parts undesirably resonate at a frequency f, where f is a function of a temperature t of those mechanical parts. The servo system includes a notch filter responsive to an indication of temperature t, to attenuate the amplitude of frequency f in a broadband control signal that is applied to move the mechanical parts.

Abstract: Apparatus and method for improved disc drive data storage capacity and seek performance. The disc drive includes a rotatable disc with a recording surface on which a plurality of tracks are defined and an actuator which supports a head adjacent the tracks. A servo circuit uses a velocity profile to position the head adjacent a destination track, with the servo circuit adaptively selecting the velocity profile in relation to the physical location of the destination track. The servo circuit preferably uses a reduced maximum velocity and a decreased deceleration rate when the deceleration track is adjacent an innermost or outermost diameter of the disc, thereby reducing the risk of damage as a result of contact between the actuator and a limit stop used to limit radial excursion of the head.

Abstract: A motor control apparatus for adjusting a gain by identifying an inertia includes a speed control section for determining a torque command and controlling a speed of a motor such that an actual speed of the motor coincides with an inputted speed command; an estimation section for simulating and creating a model of the speed control section so that the motor speed coincides with the speed of the model; and an identifying section for identifying an inertia on a basis of a ratio between a first value which is obtained by time-integrating a first speed deviation of the speed control section during a specified period and a second value which is obtained by time-integrating a second speed deviation of the estimation section during the same period as the specified period, wherein identification of the inertia is performed only in a case where the motor speed within the speed control section and the speed of the model within the estimation section are not zero and coincide to each other, and the inertia is identified

Abstract: A circuit to pull down a driver circuit of a motor, including a circuit to monitor the input signal to a driver amplifier to compare the input signal with the output signal from the motor and to output a difference signal when the input signal and the output signal are different, and a circuit to pull down the driver circuit in response to the difference signal.

Abstract: A method and apparatus for substantially reducing tonal noise and or vibration generated by a rotating machine. The power supplied to the rotating machine or motor drive signal is modulated as a function of time so that the shaft rate of the rotating machine is varied as a function of time. The motor drive signal or power signal can be modulated in an alternating current (AC) machine wherein the shaft rate is related to the power line frequency, as well as a direct current (DC) machine wherein the shaft rate is related to the DC level applied, to alter the shaft rate as a function of time. Such drive power modulation causes the drive signal energy to spread into new frequencies. As a result, the radiated tonal components are spread out such that the strength of the rotating machine's tonal radiation is substantially reduced. In addition, "beating" effects related to the operation of multiple machines can be reduced.

Abstract: The invention detects vibrations of a motor by a vibration detection means, compares the detected vibration detection value with a reference value using control means, and changes the voltage to be applied to each of coils of the respective excitation phases until the vibration detection value reaches the reference value, thereby controlling the excitation currents that flow through the coils of the respective excitation phases to reduce the vibrations of the motor.

Abstract: A method of damping resonances in a rotating system is disclosed, which includes developing a representation of vibrating movement in the rotating system, taking the derivative of that representation and applying an out-of-phase active damping force based on the derivative to the rotating system to damp out the movement.

Abstract: The present invention relates to a gimbal assembly having a belt driven mirror, wherein an active vibra-acoustic damper is used to reduce vibra-acoustic energy induced line of sight disturbances resulting from belt mode resonant amplification. Exemplary embodiments of the present invention improve system performance far beyond the capability of a passive damper by actively countering vibra-acoustic disturbance torque and line of sight disturbances (i.e., substantially reducing and/or effectively canceling these disturbances).

Abstract: A control system stabilizes the flexible body bending modes of a space, airborne, or ground-based system, while providing angular position control of an oscillating mass connected to a counter-oscillating counterbalance. The actuating mechanism uses two drive motors to exert torques on the mass and counterbalance, respectively, under the control of a feedback controller. The controller has a first control channel generating a first torque command signal for the first drive based on the angular position of the mass, and a second control channel generating a second torque command signal for the second drive based on the angular position of the counterbalance and a torque cross-feed signal from the first control channel. The second control channel includes a notch filter for removing input frequencies in a predetermined bandwidth about the frequency of the first torque command signal.

Abstract: A method and circuit for controlling a motor and reducing and/or eliminating mid-velocity instability in the motor are provided. The method includes the step of receiving a decay time indicative signal that is indicative of the current decay time in a phase coil of the motor after current commutation. The decay time indicative signal assumes a first polarity proportional to the current decay time in the phase coil. The method further includes the step of calculating a delay time corresponding to the amount of time the decay time indicative signal has the first polarity. Finally, the method includes the step of controlling the direction of current in the phase coil or another phase coil of the motor responsive to the delay time and a current direction signal generated by a translator. The inventive method and circuit enable reduction and/or elimination of mid-velocity instability even when the motor is operated in a microstepping mode.

Abstract: The present invention provides vibration control for a vehicle drivetrain. In one embodiment of the present invention, a vibration control method comprises generating a speed signal representing a rotational speed of the drivetrain. The method further includes half-wave rectifying the speed signal to generate a first signal. Also, the method comprises inverting the speed signal and half-wave rectifying the inverted signal to generate a second signal. Also, the method includes low-pass filtering the first signal to generate a third signal and low-pass filtering the second signal to generate a fourth signal. In addition, the method comprises selecting a minimum of the third and fourth signals to generate a fifth signal.

Abstract: A controller is provided for a multi-axis robot having at least first and second axis assemblies, the first and second axis assemblies each having an arm, a servomotor driven by a control input and a coupling in the form of a decelerator, which includes a spring element, coupling the servomotor and the arm, the second axis assembly being disposed at an end of the arm of the first axis assembly. The controller includes the first and second axis assemblies each including torsional angle detector for detecting a torsional angle of a respective one of the couplings. A dynamic coupling calculator calculates coupling parameters of the couplings. The first and second axis assemblies each include a semi-closed loop.

Abstract: The present invention relates to an electromagnetic motor, in particular a linear motor, and to active vibration-control apparatus including at least one such motor. Said motor has a plurality of actuators, at least of which are disposed side by side and operate in alternation to exert forces in opposite directions.

Abstract: An adaptive feed forward device for decreasing current control errors, includes an adaptive feed forward controller which provides adaptive feed forward values, establishing a linear slope flexibly adjusting to the current command values for the servo control of the hard disk drive, in a deceleration section of the servo control during a track seek.

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 apparatus and method for reducing vibrational noise generated by the operation of a machine. The machine includes an electric motor that is driven by a drive current generated by a power source. The vibrational noise generated by the operation of the machine induces a waveform in the drive current. An input device monitors the waveform of the drive current and quantifies the induced waveform. A signal processor translates the quantified waveform into a control waveform. A control device adds the control waveform to the drive current, thereby reducing the vibrational noise generated by the machine.

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 (60) for an EGR valve (24) including an actuator (16) for moving the EGR valve (24) between a closed position and an open position, and a position sensor (48) for detecting the position of the EGR valve (24) and generating a position output signal. A processing circuit (70,72) receives the position output signal and transmits electrical control signals to energize the actuator (16) and move the EGR valve (24). Control logic is implemented whereby, when the EGR valve (24) is moving towards the closed position, the processing circuit (70,72) transmits first electrical control signals for energizing the actuator (16) in a first predetermined manner when the position output signal indicates that the EGR valve (24) is at least a predetermined distance away from the closed position.

Abstract: Robust Vibration Suppression methods and systems providing improved robustness range and are effective in single or multiple degree of freedom systems are disclosed. Methods disclosed include providing an output response from a physical system by selecting a command input to be applied to a physical system based on robustness and/or noise generation potential as determined by analyzing the acceleration frequency spectra of the command inputs. Also disclosed are specific robust command inputs and methods for deriving new robust command inputs.

Abstract: A driving circuit for generating a motor driving voltage has a positive feedback loop for feeding back the motor driving voltage through a filter. The filter is arranged so as to have a transfer function given as G.sub.F (s) which (1) satisfies G.sub.F (s).apprxeq.1 in a frequency band in which disturbances should be suppressed while (2) satisfies .vertline.G.sub.F (s).vertline.<.vertline.G.sub.open .vertline. in a full range of frequencies, where G.sub.open represents an open loop transfer function of a motor control device in which a positive feedback loop is not provided. With this arrangement, it is possible to suppress disturbances, irrelevant to motor characteristics which may vary. Besides, it is possible to provide a motor control device in which computations for disturbance compensation are considerably decreased.

Abstract: A velocity control device controls a velocity of an object via a servo motor so that a damping phenomenon during acceleration or deceleration and a swelling phenomenon of a specified frequency arising at a specified velocity are relieved, while disturbance suppression ability is improved under a wide range of low accelerations. The device comprises an integral gain variable calculation section including an acceleration variable section for calculating an acceleration variable integral gain from an acceleration factor according to an acceleration command value and a reference integral gain and a weighting calculation section for calculating an integral gain from a weighting factor according to a velocity command value, a reference integral gain, and an acceleration variable integral gain. The device may therefore variably set an integral gain according to an acceleration command value and a velocity command value.

Abstract: A method of estimating the gain of a servo control system including an actuator, in which input data supplied to the actuator and the actuator's position data are applied to a gain estimate formula in a closed loop discrete value system for controlling the actuator, so as to estimate the gain of the servo control system.

Abstract: A process and apparatus for positioning an object being moved along a path to a destination using a pole changing three-phase induction motor having at least two fixed driving speeds. The object is initially accelerated along the path of movement to the highest driving speed of the motor, during which the acceleration curve is determined and stored. The acceleration data is then used to calculate the location along the path in advance of the destination at which the motor is switched off and braked until reaching the next lower driving speed, whereupon the motor is operated at the next lower driving speed for a predetermined path length. The motor is then again switched off and braked until its driving speed reaches zero closely proximate the destination, at which point a motor in a gear assembly attached to the motor is operated for final low speed positioning of the object at the destination with a high degree of accuracy.

Abstract: In a stage for supporting an article, e.g. for a microlithographic system, the stage rides on a base and is driven in two orthogonal directions on the base along magnetic drive tracks by several drive coils riding in the drive tracks. Each drive coil, rather than being rigidly mounted to the stage, instead is connected to the stage by a tapered connecting member (beam). One end of each beam is connected to the stage by a double flexure assembly. The other end of each beam is connected to the drive coil by a similar double flexure assembly. Each double flexure assembly includes two orthogonal flexible members (stainless steel strips). Thus vibrations are reduced by use of this multiple flexible joints.

Abstract: A position control device for driving a movable member by a motor to a target position prevents a re-start of the motor by the vibration after stopping of the movable member. A re-start operation is forcedly inhibited during a predetermined period after a stopping operation of the movable member at the target position, and is permitted, only after the predetermined period, is entered by the position of the movable member is different from the target position.

Abstract: A servomotor controlling method and apparatus for use in two inertial systems in which the servomotor and a load are mutually connected by an elastic connection element is provided. A compensation torque value for suppressing oscillation is obtained on the basis of a torque command value for the servomotor and a motor output velocity. The compensation torque value is reflected on the torque command value to then be provided to the servomotor. Accordingly, a resilient torsional torque generated between a driving inertial system and a driven inertial system is properly corrected to thereby suppress oscillation and improve system stability.

Abstract: An apparatus has a mass suspended between two mounting plates by a separate springs to form a resonant structure that absorbs vibration in a structural member to which the mounting plates are attached. Permanent magnets are fixed to opposite sides of the mass. A sensor produces a signal indicating the frequency of the vibration. A feedback circuit receives the signal from the sensor and produces an output signal having first component frequency which corresponds to a harmonic of the frequency of the vibration. The output signal is applied to a separate voice coil adjacent to each permanent magnet. The magnetic fields produced by the output signal flowing through the voice coils interact with the magnetic fields from the permanent magnets to generate forces that act on the mass in a manner that increases the impedance of the absorber to the vibration in the structural member.

Abstract: Dimpling of a workpiece by rebounding of a magnetic repulsion punch mechanism, when operated at high punching rates, is avoided by application of a damping pulse at a point at or subsequent to a mid-point of a return stroke of the punch from the workpiece and preferably within the last 10% of the return stroke. This damping pulse is preferably a fraction of the pulse width and of approximately the same amplitude as a driving pulse applying kinetic energy to the punch for causing punching of the workpiece. At high punching rates the kinetic energy of the return portion of a punching stroke is substantially determined by elastic rebounding of the punch from a guide bushing. The removal of kinetic energy during the return portion of the stroke allows the return of the punch to a position close to a rest position during a very short interval with small overshoot under control of mechanical damping.

Abstract: It comprises a mechanical power input (1, 55) receiving the power preferably from an electric motor and a mechanical power output (3, 67), as well as transfer means (2, 2', 2", 2'", 4, 64) for transferring this power from the input to the output, and control means (2, 5, 6, 7, 59, 60, 61) for controlling the transfer means (2, 4, 64) to make sure that the power transferred at the output does not exceed a predetermined level. There are provided means to break down the power received at the input into a power applied at the output (3, 67) and excess power which is used to produce the cut-off of power supplied by the motor. This excess power is controlled by the pressure of element (6, 7, 61) whose tension is adjustable which actuates against a movable surface which defines a cam profile, thereby increasing the force or torque during the angular or linear motion of the cam (2, 2', 2", 2'"). The transfer mechanism includes a basic group with four different output alternatives (C1, C2, C3 and C4).

Abstract: An excitation control device controls excitation of a synchronous machine so as to absorb the harmonic current of a specified order superposed onto the current flowing between an electric power system to the synchronous machine.A harmonic detector selectively passes a harmonic component of the order of 6n.+-.1 in the detection signal detected by a current transformer. A pass signal of the harmonic detector is. 3-phase/2-phase converted by a rotating coordinate circuit into components on the orthogonal 2 axes on the rotating coordinate system rotating at an angular frequency of a fundamental current of the electric power system. At this time, the pass signal is calculated as a 6n-order harmonic current represented by the components on the normal two axes. The obtained 6n-order harmonic current is retrieved through a 6n-order harmonic filter, amplified by a power amplifier, and provided as an excitation current for the synchronous machine.

Abstract: For the suppression of radio frequency emissions from an electrical drive comprising an electric motor supplied with electrical power via an electronic controller having a high speed switching device which generates high frequency energy, an electrical screen is provided to receive the radio frequency energy and is connected back to the input side of the high speed switching device.

Abstract: A control system for controlling overshoot in response to a setpoint input to the control system is provided. The control system includes a feedback loop connected to the control system via a summing node; and a binomial filter arranged to receive a setpoint input and to provide a filtered setpoint output to the control system via the summing node. The control system includes the binomial filter to provide a filtered setpoint output having a gradual initial response to the control system via the summing node. A method of controlling a water chiller system to provide a supply of leaving water at a preselected temperature is also provided. The method has the steps of: providing a control system for the water chiller system, the control system having an input; selecting a setpoint temperature; filtering the setpoint temperature using a binomial filter to provide a filtered setpoint; and providing the filtered setpoint to the input of the control system.

Abstract: The system disclosed herein controls the vibratory energy radiated from a structure subject to excitation from an outside disturbance by enforcing a preselected mechanical impedance upon at least one point in the structure using an electromechanical transducer connected to the structure at that point. The transducer is energized in response to the output of an adjustable or adaptable filter. Sensors provide signals representing the force applied by the transducer and the resultant velocity. The force and velocity signals are applied as inputs to the adaptable filter through circuit means including a component providing an electrical analog of the preselected mechanical impedance. The adaptable filter is then controlled to reduce the amplitude of the input signal applied to the filter, i.e. the error between the measured mechanical impedance and the desired impedance.

Abstract: The present invention relates to a device (1) for damping the vibrations of a structure (2) subjected to dynamic stresses, of the type including a main mass (3) mounted on an elastic plate (4) which is itself fitted into the structure (2) whose vibrations are to be damped.According to the invention, the damping device (1) additionally comprises at least one auxiliary mass (5) connected to said main mass (3) and capable of being moved at least substantially parallel to said elastic plate (4) as a function of the control pulses which are received from a computer (9) and are computed from signals output by a first (10) and/or a second accelerometer (11) respectively measuring the vibrations of said structure (2) and those of said main mass (3).

Abstract: A rotation position detecting circuit for a sensor-less motor and a motor device include a motor (1) which is rotated and driven by adding a sensor signal having a high frequency to a sine wave drive signal and cosine wave drive signal through adders (5S) and (5C), respectively. Further, a sensor signal is extracted and demodulated from a signal flowing in the motor (1) by a band pass filer (9), and this is defined as a rotation position detection signal. In the sensor signal from the band pass filter (9), its current value is changed corresponding to a change of an impedance resulting from a rotation of a magnet of the motor. As a result, it is possible to detect the rotation position of a rotor magnet by detecting the change of the current value.

Abstract: A system and method for reducing non-repeatable positioning errors. Non-repeatable positioning errors caused by the effects stiction and backlash in the mechanical system are reduced by "shaking" or vibrating the positioning system in a controlled manner. After the system input is set to the desired value, the positioning system is "shaken" by inputting a series of offsets that oscillate around the desired location and gradually decrease in amplitude, eventually reaching zero. In a specific embodiment, a lead screw is threaded through a follower nut which is connected to a magnetic tape read/write head. The lead screw is rotated by a mechanical transmission which provides gear reduction from a computer controlled stepper motor. The tape head's non-repeatable positioning error is reduced by alternately stepping the stepper motor in opposite directions a specified number of steps and periodically reducing the specified number of steps until zero is eventually reached.

Abstract: A second circuit B which is composed of a band-pass filter circuit (5) which takes out a rotating body position signal input from a sensor (1) while scarcely varying a phase within a range including a normal rotation frequency and a reverse rotation frequency of a rotating body, a gain circuit (6) for controlling a gain of an output signal from the bandpass filter circuit (5) and a second notch filter circuit (7) for attenuating components having frequencies lower than the natural frequency of an output signal from a gain circuit (6) is disposed separately from a main circuit A, and an output signal from the second notch filter circuit (7) is positively fed back to the main circuit A through an adding circuit (8).

Abstract: A motor drive control circuit for operation in both linear and PWM modes includes a switchably connected compensation network. The compensation network has a capacitor that provides control loop compensation. To avoid transient effects during the settling time upon transitions from one mode to the other, the switch connecting the compensation network in the circuit is closed only during linear operation and not during PWM mode operation. When the switch is open, the capacitor holds a previously attained potential that is reapplied to the circuit when the switch is again closed.

Abstract: A robot comprises a member traveling along a threaded rotary shaft which decelerates when the member approaches a predetermined location on the shaft. Rotation of the rotary shaft is subjected to a resistance imposed by a fluid whose viscosity is increasable by the application of an electrical charge to the fluid. The point at which the rotary shaft begins to decelerate is sensed, and an electrical charge is applied to the fluid to increase its viscosity and attenuate vibration of the member.

Abstract: A stage device comprises a base, a movable member movably provided on the base, a damping system for giving a damping force to the movable member, a position detector for detecting a position of the movable member with respect to the base, a deviation detector for obtaining a deviation of a position of the movable member from a target position of the movable member on the base on the basis of a result of the detection by the position detector and a damping control system for changing the damping force in accordance with the deviation detected by the deviation detector.

Abstract: A weight supporting apparatus supports the weight of a structure required to have very high surface precision, without affecting the surface precision of the structure. The weight support apparatus includes a driving unit for moving a driven body in the direction of gravity with respect to a base, and a supporting unit for supporting the weight of the driven body at a position after being driven, wherein the driving unit and supporting unit are so arranged that the drive force of the driving unit and the support force of the supporting unit are on the same axis.

Abstract: The disclosed hunting suppressor is for use with n-phase electric motors including a stator having n windings and a rotor. The hunting suppressor is responsive to a reference clock signal characterized by a frequency f.sub.c and an associated phase angle .phi..sub.c.A controlled frequency oscillator generates n drive signals, where the drive signals are mutually shifted in phase by 180/n degrees. The drive signals are each coupled to drive a respective one of the n windings of the motor. A phase locked loop network locks the frequency and phase of one of the drive signals to that of an applied clock reference signal. With that configuration, the rotor is controlled to rotate at the frequency of the clock reference signal with substantially no hunting.

Abstract: A position controller includes: a compensation torque control circuit which outputs a second torque signal T.sub.2 * and an initial value of an integration torque T.sub.iset on the basis of a real speed signal .omega..sub.M, a rotation angle instruction signal .theta..sub.M *, a real rotation angle signal .theta..sub.M, an integration torque signal T.sub.i of a speed control circuit, and a reference .theta..sub.drp *; a speed control circuit which outputs a first torque signal T.sub.1 * and the integration output T.sub.i on the basis of a speed instruction signal .omega..sub.M * and the real speed signal .omega..sub.M ; an adder which adds the first torque signal T.sub.1 * to the second torque signal T.sub.2 * and outputs a torque instruction signal; and a torque control circuit which controls the torque of the motor in accordance with the torque instruction signal.

Abstract: In the tandem control method designed for driving one axis using a main motor and a sub motor, a speed difference between the main motor and the sub motor is calculated, and a value for correction of torque is obtained based on this speed difference. Then, the value for correction of torque is added to respective torque commands of both the main motor and the sub motor, thereby making it possible to suppress vibrations occurring in the transmission mechanism. Furthermore, the sign of the torque command generated from a speed control section is detected, whereby a positive or negative torque command is suppressed in accordance with its sign, and the current control section of each motor is always supplied with a one-directional torque command whose direction differs from that of the other motor. Thus, it becomes possible to suppress the occurrence of backlash even when a large torque is applied. Furthermore, the position control is performed by the motor corresponding to the position command.

Abstract: A method and apparatus are disclosed for joining a drive band to the driven element of a servo-controlled precision motion system. A vibration dampening clamp assembly absorbs unwanted vibration energy. The clamp assembly utilizes energy absorbing molded grommets which mechanically isolate the driven element from the band. A threaded fastener passing through an axial bore in each of two energy absorbing grommets is used to join two halves of a clamp assembly. The grommets are preloaded at assembly using threaded fastener and a nut to compress each grommet to a known compression prior to tensioning of the drive band. Upon final tensioning of the band drive assembly, the grommets are brought to a final compression value.

Abstract: A method and an apparatus for recording and reproducing data on disk recording medium, capable of effectively reducing the unnecessary vibration of the spindle motor and the noises associated with it, and improving the tracking characteristic of a head with respect to the vibration of the spindle motor. The apparatus includes a head for recording and producing data with respect to a disk recording medium; a rotational driving mechanism including a spindle motor for driving the disk recording medium in rotation according to a driving waveform; and a waveform correction unit for detecting a vibration of the rotational driving mechanism and correcting the driving waveform supplied to the rotational driving mechanism according to the detected vibration.

Abstract: Vibration occurring at an arm part of an industrial robot when the arm part is moved is controlled by combining vibrations occurring at two time points for mutual interference. In each of acceleration and slowdown periods, the time difference of rise and fall time points t.sub.1, t.sub.4 and t.sub.2, t.sub.3 of a differential value of an acceleration with respect to time is set to be an integral number times the natural vibration period of the system so that the vibrations occurring at the rise and fall time points interfere with each other to cancel one another. Also, the vibration occurring in the acceleration period and the vibration occurring in the slowdown period can cancel each other.