Abstract: Motor position learning method and apparatus for an electric shift-by-wire system are proposed. The method includes setting, as a first reference position, a motor position at a time point when shift is completed; driving the motor in opposite directions on the basis of the first reference position; measuring a rotation amount of the motor and a driving current flowing through the motor while the motor is driven in opposite directions; and calculating a rotation amount of the motor at a point where the driving current of the motor becomes minimum, and setting, as a second reference position, a position resulting after the motor rotates further by the calculated rotation amount from the first reference position.

Abstract: A control device for a linear motor is disclosed which is provided with a current limiter and a driver. The current limiter outputs either a target current value or a limiting current command value. When the target current value is output as the current command value, the driver applies a voltage to the linear motor based of the value obtained by multiplying a first proportional gain by the difference between the current value of the current flowing to the linear motor and the current command value. When the limiting current command value is output as the current command value, the driver applies a voltage to the linear motor based of the value obtained by multiplying a second proportional gain, which is greater than the first proportional gain, by the difference between the current value of the current flowing to the linear motor and the limiting current command value.

Abstract: A method and arrangement for reducing the torque ripple of a brushless DC motor having a stator, a rotor, and a motor control unit, via which motor control unit the motor is controlled in a polyphase manner, having a data memory for storing rotational angle-dependent correction data of the control current of the motor, which are impressed on the instantaneous values for controlling the motor. In a first step, for each position of the rotor, the phase currents holding the rotor in this position are determined and are used to derive reference current data, which is stored in a table of the data memory together with the respective position data of the rotor, determined by the position sensor. In a second step, during continuous operation of the motor, the position-dependent reference current data stored in the data memory is combined with the control current of the motor.

Abstract: A mask assembly fabrication apparatus includes a first vibration proof apparatus formed on a base surface, a first surface plate formed on the first vibration proof apparatus, stages formed on the first surface plate, a mask frame placed on the stages, a second vibration proof apparatus formed on the base surface to be separate from the first vibration proof apparatus, a second surface plate formed on the second vibration proof apparatus to be separate from the first surface plate, and a driving unit formed on the second surface plate and configured to move a mask.

Abstract: A jointed mechanical device is provided. The device includes at least one element (204) having a fixed end and a deflectable end. The device also includes at least one actuating structure (206) having a first end coupled to at least the deflectable end of the element, where the actuating structure includes at least one elastic element (214) in series with at least one non-elastic element. The device further includes at least one force actuator (202) configured to apply an actuator force to a second end of the actuating structure. Additionally, the device includes a control system (315) for adjusting an operation of the force actuator based at least one actuation input, an amount of the actuator force, and an amount of displacement generated by the force actuator.

Abstract: A vehicle energy harvester including a subunit having an upper surface forming a roadway surface; a vehicle activated treadle on the subunit, the vehicle activated treadle moveable between a first position in which an upper surface of the treadle is at an angle with respect to the upper surface of the roadway surface and a second position in which the upper surface of the treadle is flush with the upper surface of the roadway surface; a generator that generates power in response to movement of the vehicle activated treadle from the first position to the second position and from the second position to the first position; and a capacitor coupled to the generator, the capacitor storing power generated by the generator.

Abstract: A boost converter control apparatus for controlling a motor drive system which is provided with a boost converter disposed between an electric power converter and a direct current power supply, the boost converter boosting a direct current voltage of the direct current power supply and supplying it to the electric power converter, is provided with: an operating device provided with a proportional element, an integral element and a derivative element, the derivative element being configured as a bandpass filter, the operating device calculating a PID controlled variable corresponding to an electric current command value of the boost converter for maintaining an output voltage of the boost converter at a command value of an inter-terminal voltage VH of a smoothing condenser; and a controlling device which is configured to control the output voltage of the boost converter on the basis of the calculated PID controlled variable.

Abstract: A vibration control robot system of the present invention includes: a robot controller (101) transmitting an operation command value and receiving an output value of a pulse encoder of the servo motor, wherein the robot controller includes a controller-side communication unit (5) which transmits the operation command value and the output value of the pulse encoder to a robot vibration controller; and the robot vibration controller (11) including: an acceleration sensor interface (15); a corrected operation command value calculation unit (13) which calculates a corrected operation command value obtained so as to suppress vibration of the robot; and a vibration-controller-side communication unit (12) which transmits the corrected operation command value to the robot controller (101), wherein the robot vibration controller (11) is arranged independently of the robot controller (101).

Abstract: A motor-drive circuit includes: a filter circuit to attenuate a frequency band including a resonance frequency of an actuator in a target-current signal, which is a digital signal indicating a target value of a driving current to be supplied to a voice-coil motor that drives the actuator; a digital-analog converter to convert an output signal of the filter circuit into an analog signal, to be outputted as a current-control signal; and a driving circuit to supply the driving current to the motor in accordance with the current-control signal, the filter circuit including: a digital-notch filter to attenuate a frequency band around the resonance frequency in the target-current signal; and a digital-low-pass filter to attenuate a frequency band greater than or equal to a predetermined frequency in the output signal of the digital-notch filter, the digital-low-pass filter having a sampling frequency higher than a sampling frequency of the digital-notch filter.

Abstract: An electrical machine device is disclosed, the electrical machine device including an electrical machine and a converter electrically coupled to the electrical machine. A configuration of the electrical machine generates a first vibration component in the electrical machine and the converter generates a second vibration component in the electrical machine. The electrical machine and the converter are adapted to each other such that the first vibration component and the second vibration component at least partially interfere destructively. Further, respective methods and computer programs for controlling a converter or operating a converter are disclosed.

Abstract: The invention relates to a method for absorbing the displacement, under the influence of an external force, of at least one plunger (10,20) in a linear electrodynamic motor comprising a least an induction coil (11, 21) magnetically coupled with the plunger. Said method comprises the steps of: detecting in said induction coil a current induced (I?ind) amplified relative to the induced current. The invention can be applied to cryogenic machines on board space ships.

Abstract: The stage device of the present invention includes a linear motor having a coil and a plurality of permanent magnets, a current driver that supplies current to the coil, and a control section that generates a command for the current driver. The control section generates the command through commutation processing in which a sinusoidal wave using an electrical angle obtained by calculation based on the relative position between the coil and the permanent magnet is multiplied by a thrust force command value for the linear motor, and further ensures that a sinusoidal wave component, which has an amplitude proportional to a thrust force command value and is 90 degrees out of phase from the sinusoidal wave, is included in the command.

Abstract: A method to monitor integrity of a signal output from an operator-manipulable transmission range selector for a powertrain system includes equipping the transmission range selector with a range encoder and a direction encoder, determining a range state and a direction state based upon signals from the range encoder and the direction encoder, determining a discrete position of the transmission range selector based upon the range state and the direction state, and performing back rationality to verify the discrete position of the transmission range selector.

Abstract: A drive system for a compressor of a chiller system includes a variable speed drive. The variable speed drive is arranged to receive an input AC voltage at a fixed AC input voltage and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter connected to an AC power source providing the input AC voltage. The converter is arranged to convert the input AC voltage to a DC voltage. A DC link is connected to the converter. The DC link filters and stores the DC voltage from the converter. An inverter is connected to the DC link. A motor connectable to the compressor for powering the compressor. An active filter connected in parallel with the motor. The active filter is arranged to generate high frequency currents having a magnitude and opposite polarity, with respect to the output AC power of the variable speed drive. The high frequency currents generated by active filter substantially cancel out high frequency currents flowing into the motor.

Abstract: A method and a system for video camera assembly are provided. The video camera assembly includes at least one of a pan mechanism rotatable about a pan axis and a tilt mechanism rotatable about a tilt axis. The pan mechanism includes a pan motor and a pan position encoder. The tilt mechanism includes a tilt motor and a tilt position encoder. A controller is communicatively coupled to at least one of the pan mechanism and the tilt mechanism and is configured to apply a filter to a power drive signal of at least one of the pan motor and the tilt motor based on a determined corresponding rotational speed of the at least one of the pan motor and the tilt motor with the effect of reducing steady state vibrations which degrade the visual and audible qualities of said video camera assembly.

Abstract: Methods, apparatus, and systems are disclosed for identifying force-ripple and/or side-forces in actuators used for moving a multiple-axis stage. The identified force-ripple and/or side-forces can be mapped, and maps of corresponding position-dependent compensation ratios useful for correcting same are obtained. The methods are especially useful for stages providing motion in at least one degree of freedom using multiple (redundant) actuators. In an exemplary method a stage member is displaced, using at least one selected actuator, multiple times over a set distance in the range of motion of the subject actuator(s). Each displacement has a predetermined trajectory and respective starting point in the range. For each displacement, respective section force-command(s) are extracted and normalized to a reference section force-command to define a section compensation-ratio.

Abstract: In a control device for controlling a variable damper of a vehicle suspension system, when a stroke speed of the damper is within a range including a zero stroke speed, the target damping force is determined as a force opposing a current movement of the damper without regards to the direction of the target damping force determined by a target damping force determining unit. Thereby, even when the wheels move vertically at short intervals, the control value is prevented from changing rapidly, and this allows a damping force of an appropriate level to be achieved in a stable manner at all times. Also, the target damping force when a stroke speed of the damper is within a range including a zero stroke speed may be selected to be a relatively high value or low value so that a desired vehicle behavior may be achieved.

Abstract: A method for collecting operational parameters of a motor may include controlling the energization of a phase winding of the motor to establish an operating point, monitoring operational parameters of the motor that characterize a relationship between the energization control applied to the motor's phase winding and the motor's response to this control, and collecting information of the operational parameters for the operating point that characterizes the relationship between the applied energization control and the motor's response. The collected information characterizing the relationship between the applied energization control and the motor's response may be employed by a neural network to estimate the regions of operation of the motor. And a system for controlling the operation of motor may employ this information, the neural network, or both to regulate the energization of a motor's phase winding during a phase cycle.

Abstract: An enhanced torque ripple mitigation algorithm for permanent magnet synchronous machines (PMSMs), the algorithm including compensation for sensor delay.

Abstract: A motor control system suppresses vibration of a machine base and achieves high-speed positioning without using a special sensor but using a model control system. A first feedback section outputs a first feedback command generated based on model machine base position information and containing at least position information on the machine base. A second feedback section outputs a second feedback command containing a filtered model torque command. A differential between the sum of the first feedback command and the second feedback command obtained by a second addition section and the model torque command is calculated to give the differential to an input portion of a model torque command low-pass filter and an input portion of a torque command low-pass filter.

Abstract: A method and a device with a control apparatus (50) for starting an electric machine (10) with a rotor (20), particularly the spinning cup of an open-end spinning machine, magnetically mounted by a bearing having permanent magnets (31, 32, 33, 34). An actuator system controls the position in the axial direction (35, 36) and two limitation bearings (41, 42), determine the axial end positions of the rotor. The actuator system brings about a lifting from the first axial end position, and a system variable during such lifting is compared with a reference value, and the rotor (20) is moved into the second end position, and the actuator system brings about a lifting from the second axial end position, and a system variable on lifting from the second end position is compared with a reference value.

Abstract: An accurate load position control is made possible even when rigidity of a load drive system using a motor is relatively low. Load position signal xl is a present-position measurement value of a load, and after compensation in response to a phase delay thereof has been performed by a stability compensation circuit, the high-frequency portion thereof is taken as a control-target position signal xfb by replacing, in a position-signal combination circuit, a motor position signal xm as a present-position measurement value of a motor, and then the control-target position signal xfb is fed back to a position control circuit. Thereby, a torque command signal indicating a torque target value for driving the load is outputted.

Abstract: In a vibration damping device for an elevator, an actuator for generating a vibration damping force acting on an elevator car is provided in parallel with a spring for urging a guide roller against a guide rail. The actuator is controlled by a controller. The controller determines the vibration damping force to be generated by the actuator based on information from a car frame acceleration sensor for detecting horizontal acceleration of a car frame and a car cage acceleration sensor for detecting horizontal acceleration of a car cage.

Abstract: There is provided a driving apparatus of an electric motor for a reduction roll that can improve maximization of rolling performance and a speed decrease amount by making maximal use of torque that various electric motors can generate during material entry.

Abstract: A machine tool includes a first motor, a gear, and a machine element which is movable in a direction of movement by the first motor via the gear. A second motor is provided to apply a force directly upon the machine element in the direction of movement of the machine element in the absence of an interposed gear between the second motor and the machine element. The second motor is constructed to operate in such a way that the applied force counteracts an oscillatory movement of the machine element in the direction of movement of the machine element.

Abstract: A mobile lift device having a load moving device capable of engaging a load is provided. The mobile lift device includes one or more systems for stabilizing the mobile lift device during operation of the load moving device. According to one exemplary embodiment, the mobile lift device is a heavy duty wrecker having a rotatable boom assembly. The heavy duty wrecker comprises a monitoring system for stabilizing the wrecker during operation of the boom assembly. The monitoring system comprises a plurality of sensors and a monitoring circuit coupled to the sensors to generate a force signal representative of at least one force being applied to the wrecker based upon the transmitted signals.

Abstract: A closed loop control system for controlling an actuator operating on a moveable member, includes a control device controlling operation of the actuator, a sensor responsive to a condition such as loading of the moveable member as it is moved by the actuator and adapted to generate a corresponding feedback control signal SL, and a damping device having a damping effect on the response of the actuator to the feedback control signal, the damping effect being varied in accordance with the movement of the moveable member so as to vary the response of the actuator. The damping effect is increased in the region of stationary states to render the system more stable, and reduced therebetween to make the system more responsive at increased speeds, and thereby more conformal to a required performance profile. The position or velocity of the moveable member can be used to control the damping effect, or a timer can be used to control the damping effect.

Abstract: A motion controller accurately identifies system constants, such as inertia, viscous friction coefficient, and constant disturbance, without requiring operation, even in cases where viscous friction and/or constant disturbance are present. An identifier includes a time-differentiator for calculating an acceleration detection value afb by time-differentiating a speed detection value Vfb, a first filter for calculating Fafb by filtering the acceleration detection value afb, a second filter for calculating Fvfb by filtering the speed detection value Vfb, a third filter for calculating Ftref by filtering a torque command value Tref, and a JDC estimator for calculating an inertia identification value J_hat, a viscous friction coefficient identification value D_hat, and a constant disturbance identification value C_hat of a control object by performing time-differentiation and four arithmetic operations based on Ftref, Fvfb and Fafb.

Abstract: A galvano motor 10 includes a motor shaft 1, a coil 5 which rotationally drives the motor shaft 1, and an encoder scale 6 which is joined to one end of the rotating shaft, the motor shaft 1 is configured so that a mirror 9 which is heavier than the encoder scale 6 at the other end opposite to the one end to which the encoder scale 6 is joined, a phase crossover frequency fphase in open-loop characteristics of the galvano motor 10, a torsion resonance frequency fscale between a center part of the motor shaft 1 and the encoder scale 6, and a torsion resonance frequency fmirror between the center part of the motor shaft 1 and the mirror 9 satisfy the relation of fphase<fscale?fmirror, and phases at the torsion resonance frequencies fscale and fmirror are other than ?180 degrees.

Abstract: A method and a controller for controlling a magnetic bearing device, in which a rotor is suspended for rotation around a shaft, are disclosed. Sensor signals are transformed to yield tilt displacement signals (S?x, S?y) which correspond to tilting displacements of the shaft in predetermined directions (x, y). From the tilt displacement signals (S?x, S?y), tilt control signals A?x, A?y) are derived; these are transformed to yield actuator control signals for driving electromagnetic actuators in the magnetic bearing device. According to the invention, tilting displacements for which the tilt vector rotates about the device axis (z) with a first predetermined sense of rotation are controlled separately from tilting displacements for which the tilt direction vector rotates about the device axis (z) with a second sense of rotation opposite to the first predetermined sense of rotation. In this way, control of nutation and precession can be achieved without influence from blade vibrations or shaft bending modes.

Abstract: A mobile lift device having a load moving device capable of engaging a load is provided. The mobile lift device includes one or more systems for stabilizing the mobile lift device during operation of the load moving device. According to one exemplary embodiment, the mobile lift device is a heavy duty wrecker having a rotatable boom assembly. The heavy duty wrecker comprises a monitoring system for stabilizing the wrecker during operation of the boom assembly. The monitoring system comprises a plurality of sensors and a monitoring circuit coupled to the sensors to generate a force signal representative of at least one force being applied to the wrecker based upon the transmitted signals.

Abstract: An electric engine starting system includes a permanent magnet motor that is used to start the engine and then to generate power for powering a load while the engine is running. A disclosed system includes a first phase controlled rectifier in series with a power converter and a second phase controlled rectifier. During an engine starting operation, the first phase controlled rectifier is switched to couple the permanent magnet motor to a power source for starting the engine. Once the engine is running, the first phase controlled rectifier is switched off and the second phase controlled rectifier is switched on. The second phase control rectifier converts variable AC power from the motor into DC power. The power converter converts the DC power into an appropriate power for driving the load. One disclosed example includes a filter between the power converter and the load to ensure that the load receives a selected quality of power.

Abstract: Methods, apparatus, and systems are provided for regulating the operation of a drive system within a battery voltage and power range. The apparatus includes a PI regulator producing a signal for regulating a torque output of the drive system based on a DC voltage source limit and/or power limit, a converter normalizing the signal from the PI regulator to produce a new torque limit, and a switch selecting either the new torque limit or an available torque limit of the drive system. The PI regulator includes an integrator having an initial value based on the torque output of the drive system and a copper loss term.

Abstract: It is an object of the present invention to provide a method for extracting a maximum gain of a servo controller in which while a machine is vibrated by raising a control gain, the vibration is rapidly detected so that the machine does not greatly vibrate or noise is not generated. In a method for extracting a maximum gain of a servo controller for driving a servo motor, a simulated disturbance torque is applied to a torque command by a vibrating unit while a control gain is raised and the vibration of a control system is detected by a vibration detecting unit (1). A process for applying the simulated disturbance torque is repeated while the control gain is raised until the vibration of a prescribed level is detected. The control gain when the vibration detecting unit (1) detects the vibration exceeding the prescribed level is set as a maximum gain.

Abstract: A system, method, and article for protecting a power source for a machine from sudden changes in load. In one embodiment, energy is wasted in a winding of a motor in response to a decrease in a load presented to the power source.

Abstract: A movable body position control device includes a pair of position detectors configured to detect moving positions of both ends of a movable body; a pair of driving parts, the driving parts being configured to drive the both ends of the movable body based on a detection signal from the pair of the position detectors; a translation control part configured to make the driving parts can generate a driving force whereby a difference of translational action of the movable body can be prevented in a case where a moving speed of the movable body is changed due to a disturbance, and configured to control the driving parts so that detected positions of the position detectors can be consistent with each other; and a rotation control part configured to make the driving parts can generate the driving force whereby a rotational action of the movable body can be prevented in a case where the moving speed of the movable body is changed due to the disturbance and the movable body is displaced in a rotational direction, and c

Abstract: A method for differentiating if a feedback signal is a result of an unintentional collision in a servo system includes injecting a feed forward term in the servo system.

Abstract: A system, method, and article for protecting a power source for a machine from sudden changes in load. In one embodiment, energy is wasted in a winding of a motor in response to a decrease in a load presented to the power source.

Abstract: An object of this invention is to provide a gain adjusting method in a servo control device to suppress changes according to a place where a machine is located. This invention provides a gain adjusting method for a servo control device providing speed control of inputting a difference between speed feedback supplied from a servo motor and a command value to output a torque command, characterized in that after a speed loop gain is increased to detect vibration at each of points moved over a movable range of a machine, the speed loop gain is decreased to detect the gain when the vibration becomes still as a maximum value, thereby providing a set gain value corresponding to a machine.

Abstract: Before an amount of play in a rotation transmitting system is learned, for selecting a gear range, an overshooting control process is performed to cause the angular displacement of a motor to overshoot a target gear range position and then reverse the electric motor. The angular displacement of the motor overshoots the target get gear range position by an overshooting amount that is identical to am amount by which the electric motor is reversed. The overshooting amount is set to a maximum value of a designed amount of play in the rotation transmitting system After the amount of play is learned, for selecting a gear range, a target count is established in view of the learned amount of play and the direction in which the motor rotates, and the motor is stopped at a position where an encoder pulse count coincides with the target count without performing the overshooting control process.

Abstract: Oscillation and other disturbance damping is provided for a system having a load driven by an electric motor, e.g., an electromagnetic actuator. Damping is achieved using feedback in an active mode, where power is supplied in a normal operation mode of the electromagnetic actuator. Feedback may be provided by measured force (or torque) transmitted between the actuator and load mass. A gear train or other mechanical advantage device may be connected between the electromagnetic actuator output and load, this combination forming an electromechanical actuator (EMA). Instead of force or torque, acceleration of the load may be used as a feedback signal. In one embodiment, active mode damping uses the motor's actual current as a feedback signal. In certain or all active damping versions of the invention, a high pass filter is preferably used to receive feedback signals and filter out low frequency feedback. Alternatively, damping is achieved in an inactive (passive) mode of motor operation, e.g.

Abstract: A lithographic projection apparatus in which a reaction force is generated between a balance mass and a substrate table. The balance mass is elastically coupled to the base frame with a suspension eigenfrequency of between 0.3 and 10 Hz.

Abstract: A method for differentiating if a feedback signal is a result of an unintentional collisions in a servo system includes injecting a feed forward term in the servo system.

Abstract: The invention concerns a method for stabilizing the motion of an articulated chain of a chain block, especially to prevent the formation of resonance oscillation of the chain, in which an articulated chain is led across a polygonal chain wheel with non-uniform pitch, which is driven by an electric motor. In order to create a method to prevent the formation of a resonance oscillation of the articulated chain, it is proposed that a periodic and/or stochastic and dampening actuating variable is superimposed on the velocity of the chain wheel (4) and the dampening actuating variable produces a change in the chain velocity so as to prevent a formation of a resonance oscillation. The chain drive with reduced polygon effect is characterized in that an electronic damper (8) is hooked up in front of the electric motor (2), which produces a control of the electric motor (2) such that a formation of a resonance oscillation of the articulated chain (5) is prevented.

Abstract: A stepping motor driving system includes: a stepping motor that rotates at a predetermined angle according to a driving pulse signal, a vibration detector that detects vibration to output a vibration signal, and a stepping motor control unit that controls the driving pulse signal, which is applied to the stepping motor, to rotate the stepping motor at the predetermined angle. The driving pulse signal includes a start-up current which is required for rotating the stepping motor at a unit angle and a holding current which maintains a rotational angle of the stepping motor rotated by the start-up current. The stepping motor control unit changes the level of the holding current according to the vibration signal which is outputted from the vibration detector.

Abstract: A motion controller for maintaining a controlled system on a switching hyperplane regardless of the magnitude of disturbance. The motion controller includes a target position generator, a sliding mode controller, a disturbance observer and a state observer. The target observer generates a target position to the sliding mode controller based on position and velocity data. The state observer estimates the state of the controlled system and provides the state to the sliding mode controller. And, the disturbance observer provides an estimated disturbance to the sliding mode control. The sliding mode controller generates a control input to the controlled system with the nonlinear component set to equal the negative estimated disturbance and the linear component based on the estimated state and target position.

Abstract: To appropriately detect overload which may break a motor or deform a body and reduce the overload in the motor. The DC component of a load torque is derived from the sum of absolute values of a torque applied to a link connected to the output shaft of a motor and the generated torque of the motor, and it is determined that overload has been applied when the DC component exceeds a first threshold value for a prescribed period of time or longer. In addition, considering such a characteristic that the variation of energy applied to the output shaft of a motor is in proportion to a product of the torque and the angular velocity of the motor, the AC component of the load torque is detected based on the variation of energy, and it is predicted that overload will be applied when the AC component exceeds a second threshold value.

Abstract: To appropriately detect overload which may break a motor or deform a body and reduce the overload in the motor. The DC component of a load torque is derived from the sum of absolute values of a torque applied to a link connected to the output shaft of a motor and the generated torque of the motor, and it is determined that overload has been applied when the DC component exceeds a first threshold value for a prescribed period of time or longer. In addition, considering such a characteristic that the variation of energy applied to the output shaft of a motor is in proportion to a product of the torque and the angular velocity of the motor, the AC component of the load torque is detected based on the variation of energy, and it is predicted that overload will be applied when the AC component exceeds a second threshold value.

Abstract: To appropriately detect overload which may break a motor or deform a body and reduce the overload in the motor. The DC component of a load torque is derived from the sum of absolute values of a torque applied to a link connected to the output shaft of a motor and the generated torque of the motor, and it is determined that overload has been applied when the DC component exceeds a first threshold value for a prescribed period of time or longer. In addition, considering such a characteristic that the variation of energy applied to the output shaft of a motor is in proportion to a product of the torque and the angular velocity of the motor, the AC component of the load torque is detected based on the variation of energy, and it is predicted that overload will be applied when the AC component exceeds a second threshold value.

Abstract: To appropriately detect overload which may break a motor or deform a body and reduce the overload in the motor. The DC component of a load torque is derived from the sum of absolute values of a torque applied to a link connected to the output shaft of a motor and the generated torque of the motor, and it is determined that overload has been applied when the DC component exceeds a first threshold value for a prescribed period of time or longer. In addition, considering such a characteristic that the variation of energy applied to the output shaft of a motor is in proportion to a product of the torque and the angular velocity of the motor, the AC component of the load torque is detected based on the variation of energy, and it is predicted that overload will be applied when the AC component exceeds a second threshold value.