Abstract: An automated vise is disclosed. A gross moveable jaw drive has a stroke longer than the stroke of a fine moveable jaw drive. With this construction, the gross moveable jaw drive can be utilized to actuate the one or more moveable jaws of the vise over a distance greater than the fine moveable jaw drive stroke to a position in which actuation of the fine moveable jaw drive is capable of positioning the one or more moveable jaws in a clamp position to apply pressure to hold the workpiece for machining by, e.g., a CNC machine. In this way, the automated vise can account for workpieces of differing size.

Abstract: A method for starting a synchronous motor is provided. The synchronous motor includes a rotor for creating a first magnetic field and a stator with stator windings connected to an electrical energy converter for converting a supply voltage into a stator voltage to be applied to the stator windings to create a rotating second magnetic field interacting with the first magnetic field. The method includes applying reference stator voltages to the stator windings, where the reference stator voltages are determined from a reference current vector and a reference rotor speed, measuring stator currents, calculating an estimated rotor speed and rotor position from the applied stator voltages and the measured stator currents, calculating a speed error by subtracting the estimated rotor speed from the reference rotor speed, determining a reference torque producing current component from the speed error, and modifying the reference current vector with the reference torque producing current component.

Abstract: A method estimates a position where an abnormality has occurred. The method for estimating a position where an abnormality has occurred in a robot includes an abnormality detection step of detecting occurrence of an abnormality, and a position detection step of detecting a position where the abnormality has occurred when the occurrence of the abnormality is detected in the abnormality detection step.

Abstract: A speed control device that controls a speed of a train using a tacho-generator includes a calculating unit that calculates, when a pulse count signal obtained by conversion from an AC voltage signal that is outputted from the tacho-generator and corresponds to a rotating speed of a wheel of the train cannot be detected, a first speed using notch information, route data, and car characteristic data and calculates, when the pulse count signal can be detected, a second speed using the pulse count signal. The speed control device includes a position calculating unit that calculates a position of the train using the speed calculated by the calculating unit.

Abstract: Provided herein are systems, methods, and software for improving drive efficiency in an industrial automation system. In one implementation, a system comprises a mechanical load, an electromechanical device attached to the mechanical load, and a drive coupled to the electromechanical device. A processor is programmed to generate and display an acceleration curve, a duplicate acceleration curve, an energy curve and a duplicate energy curve. A user input is received indicating a change to at least a portion of the duplicate acceleration curve, and a change to the duplicate energy curve is calculated and displayed. A modified command signal based on the user input is calculated, and the drive is configured to control the electromechanical device via the modified command signal to mechanically operate the mechanical load perform a task.

Abstract: A control device includes: a processor wherein the processor is configured to generate one or more second control signals obtained by reducing at least one frequency component from a first control signal, output one control signal among the first control signal and the one or more second control signals, receive an instruction indicating execution of a reduction in the frequency component, generate a driving signal for driving a robot based on the control signal output from the processor and output the driving signal, output the first control signal when a first condition including non-input of the instruction indicating the execution of the reduction in the frequency component is satisfied, and output the second control signal when a second condition including input of the instruction indicating the execution of the reduction in the frequency component is satisfied.

Abstract: A motor control device includes a control and computation unit, a compensation signal generation unit, an adder, and a drive unit. The control and computation unit is configured to perform computation processing based on a detected rotational position of a motor and a positional instruction, and to generate a first torque instruction signal to be used to drive the motor. The compensation signal generation unit is configured to generate a torque compensation signal to be used to compensate the first torque instruction signal. The adder is configured to add the torque compensation signal to the first torque instruction signal, and to output an acquired signal as a second torque instruction signal. The drive unit is configured to generate a drive signal to be used to power-drive winding wires of the motor based on the second torque instruction signal.

Abstract: A low-frequency torque controller 9 outputs a low-frequency torque controller output ?dc* based on a torque command value ?* and a torque detection value ?det, and a vibrational torque controller 11 outputs a vibrational torque command value ?pd* based on the torque command value ?*, the torque detection value ?det, and a rotational phase detection value ?. Meanwhile, in a high-frequency resonance suppression controller, an inverter torque command value ?inv* is outputted based on the torque detection value ?det and a corrected torque command value ?r* obtained by adding the low-frequency torque controller output ?dc* to the vibrational torque command value ?pd*. The invention thus provides shaft torque vibrational control of a motor drive system wherein engine vibrational torque command values including distortion components are tracked while entirely removing the influence of resonance, non-periodic disturbances, and periodic disturbances.

Abstract: A control device includes a processor wherein the processor is configured to: receive designation of one or more frequency components, generate one or more second control signals obtained by reducing at least one of the frequency components from a first control signal, generate one or more third control signals obtained using two control signals among the first control signal and the one or more second control signals, output one control signal among the first control signal, the one or more second control signals, and the one or more third control signals, and generate and output a driving signal to drive a robot based on the one control signal.

Abstract: A confocal imaging apparatus for inspecting an object comprises a light source operative to project light to illuminate the object, and an imaging device for receiving light reflected from the object along a lighting path located between the object and the imaging device. A pinhole array comprising a plurality of pinholes is positioned along the lighting path such that light reflected from the object is passed through the pinhole array. A mechanism is operative to move the pinhole array along a single axis in a linear direction transverse to the light path for transmitting an image corresponding to a substantially contiguous area of the object onto the imaging device.

Abstract: To suitably set a control gain in feedback control while suppressing an increase in apparatus size. A workpiece transport control system includes: one or a plurality of motion guidance devices; a table on which a workpiece is to be placed; an actuator which imparts a driving force to the table; a control unit which performs transport control by feedback control; and a calculation unit which calculates a transport load applied from the workpiece to a moving member of each of the one or a plurality of motion guidance devices, wherein a control gain related to the feedback control in the transport control is adjusted on the basis of the transport load in each of the one or a plurality of motion guidance devices.

Abstract: A method of monitoring a position sensor includes calculating an absolute value of a sine signal and an absolute value of a cosine signal from the position sensor. At least one of the absolute value of the sine signal and the absolute value of the cosine signal is compared to a minimum threshold to determine if the at least one of the absolute value of the sine signal and the absolute value of the cosine signal is less than the minimum threshold, or if the at least one of the absolute value of the sine signal and the absolute value of the cosine signal is equal to or greater than the minimum threshold. A fault with the position sensor is indicated when the at least one of the absolute value of the sine signal and the absolute value of the cosine signal is less than the minimum threshold.

Abstract: A curvilinear encoder is provided in which an incremental or absolute position for a cart can be detected on a track by applying one or more excitation signals and receiving one or more pick up signals. Analogous to a transformer arrangement, an encoder mover can be placed on the cart moving along the track, and an encoder stator can be placed on the track separated by a gap. The one or more excitation signals can be applied to the one or more excitation coils on the mover or the stator to generate one or more magnetic fields, and the one or more pick up signals can be received by one or more pick up coils on the mover or the stator for sensing changes in the magnetic fields produced by motion of the mover on the track.

Abstract: A linear and curvilinear encoder is provided in which absolute mechanical position and high resolution position determination can be obtained using a cart having a mover with “hybrid” teeth, configured in a curvilinear profile or shape, moving along a curvilinear track with a stator having teeth. The absolute mechanical position and high resolution position determination can be detected on the track by applying an excitation signal to a coil surrounding particular teeth of the stator to produce an electromagnetic (EM) field which can be influenced by the profile or shape of the teeth of the mover. A resulting pick-up signal can then be detected in a pick-up coil surrounding particular teeth of the stator with different harmonics in the pick-up signal corresponding to harmonics of the profile or shape of the teeth.

Abstract: Provided herein are systems, methods, and software for improving drive efficiency in an industrial automation system. In one implementation, a system comprises a mechanical load, an electromechanical device attached to the mechanical load, and a drive coupled to the electromechanical device. A processor is programmed to generate and display an acceleration curve, a duplicate acceleration curve, an energy curve and a duplicate energy curve. A user input is received indicating a change to at least a portion of the duplicate acceleration curve, and a change to the duplicate energy curve is calculated and displayed. A modified command signal based on the user input is calculated, and the drive is configured to control the electromechanical device via the modified command signal to mechanically operate the mechanical load perform a task.

Abstract: A power tool includes a motor having an output shaft, an extensible member driven by the motor, a working assembly movable in response to contact with a distal end of the extensible member, a first sensor configured to detect a home position of the extensible member, a second sensor configured to detect rotation of the motor output shaft, and a controller in electrical communication with the first and second sensors. The controller is configured to drive the motor output shaft in a first rotational direction a predetermined number of revolutions counted by the second sensor, thereby displacing the extensible member from the home position. The controller is also configured to drive the motor output shaft in an opposite, second rotational direction to thereby return the extensible member until the home position is detected by the first sensor.

Abstract: In a method and device for the cyclic digital transmission of a position value of a moving object with inertial mass, the value range of the transmitted position value is restricted such that no complete rotation or, in the case of a linear motion, other complete period caused by mechanical conditions may be mapped, and the actual position is formed by detecting value-range exceedances in an evaluation unit.

Abstract: The current disclosure relates to an angular sensor. The angular sensor includes a sensing module, a digital processor and an incremental interface. The sensing module is configured to generate a sensing signal containing measurements of rotation activities of a rotating physical entity. The digital processor is configured to process and store the sensing signal. The incremental interface is coupled to the digital processor and includes an incremental pulse generator and a status data encoder. The incremental pulse generator is configured to convert and transmit the sensing signal as incremental square pulses through a unidirectional signal line, which are processed to generate rotary angle and direction of the physical entity. The status data encoder is configured to convert and transmit the sensing signal as a reference pulse and a status signal through a bidirectional signal line, which can be to request an absolute angle position or other sensor data.

Abstract: A propeller alignment device is described. The propeller alignment device can include a second retainer attached to a propeller and a motor. The propeller alignment device can also include a first retainer that does not rotate, but that is aligned with the second retainer. The first retainer can include two or more magnets oppositely orientated relative to each other. The second retainer can also include two or more magnets oppositely orientated relative to each other. As the second retainer rotates relative to the first retainer, the magnets alternatingly align with each other. In the absence of a current applied to the motor, the magnets may magnetically bias the second retainer into a predetermined orientation relative to the first retainer.

Abstract: A first speed and a second speed slower than the first speed are set as a contact speed when a work w and a detection jig t attached to a tool post are brought into contact with each other to detect a position or a posture of the work w, the work and the detection jig are brought into contact with each other at the first speed, the detection jig and the work contacting each other are separated from each other by a predetermined distance, the work and the detection jig which are separated from each other are brought into contact with each other at the same position at the second speed, and a correction value ? is obtained based on a tool post position or a spindle angle during the second contact.

Abstract: A propeller alignment device is described. The propeller alignment device can include a second retainer attached to a propeller and a motor. The propeller alignment device can also include a first retainer that does not rotate, but that is aligned with the second retainer. The first retainer can include two or more magnets oppositely orientated relative to each other. The second retainer can also include two or more magnets oppositely orientated relative to each other. As the second retainer rotates relative to the first retainer, the magnets may alternatingly align with each other. In the absence of a current applied to the motor, the magnets may magnetically bias the second retainer into a predetermined orientation relative to the first retainer. The predetermined orientation can be predetermined to correspond to an alignment of the propeller that is desirable (e.g., that minimizes aerodynamic drag on the propeller).

Abstract: A fine-motion module for use in a wafer stage of a photolithography tool includes: a base (201); a fine-motion plate (210); a plurality of vertical motors (203), fixed between the base and the fine-motion plate; a plurality of gravity compensators (202), each having one end fixed on the base and the other end configured to support the fine-motion plate; a plurality of absolute-position sensors (205, 211), configured to measure an absolute position of the fine-motion plate and to adjust pressures in the gravity compensators based on the obtained absolute-position measurements such that the absolute position of the fine-motion plate is changed to a predetermined initial vertical position; and a plurality of relative-position sensors (204, 207), configured to measure a relative position of the fine-motion plate to the base and to control the fine-motion plate based on the obtained relative-position measurements, thereby moving the fine-motion plate to a relative zero position.

Abstract: In a method and device for the cyclic digital transmission of a position value of a moving object with inertial mass, the value range of the transmitted position value is restricted such that no complete rotation or, in the case of a linear motion, other complete period caused by mechanical conditions may be mapped, and the actual position is formed by detecting value-range exceedances in an evaluation unit.

Abstract: The present disclosure describes an ultraviolet (UV) sensor configured to detect a target UV spectrum (e.g., UVB spectrum). The UV sensor includes a first photodiode with a first UV spectral response and a second photodiode with a second UV spectral response. A filter layer having a graded spectral response is formed over the second photodiode, and the second UV spectral response is affected by a controlled parameter (e.g., thickness) of the filter layer. The UV sensor further includes a subtraction circuit coupled with the first photodiode and the second photodiode. The subtraction circuit is configured to provide a differential response based on a difference between the first UV spectral response and the second UV spectral response. The controlled parameter of the filter layer can be selected such that the differential response provides a detected spectral response of the target spectrum.

Abstract: A motor-based position system includes one or more motors having a rotor. The system further includes a motor controller. The motor controller is communicatively coupled to each of the motors. The system further includes one or more encoders configured to detect an absolute position of each motor and one or more devices configured to collect inertial data. The system further includes a processing device coupled to the motor controller, one or more encoders and one or more devices. The processing device is configured to receive signals indicative of motors' absolute position from the encoders and configured to convert the received encoder signals into a format understood by the motor controller. The processing device is further configured to send the converted signals to the motor controller with low latency and configured to combine the received encoder signals with the inertial data to generate more accurate positional information.

Abstract: A motor control device performs drive control of a motor connected to an object. The motor control device includes a rotation detection unit that detects rotation of the motor and outputs a detection signal, a counter unit that receives the detection signal from the rotation detection unit and outputs a count based on the received detection signal, and an error detection unit that receives counts from the counter unit at intervals of a reference period, computes a difference between a present count received from the counter unit and a previously received count, and detects that an error arises in the rotation detection unit when the difference is continuously less than a reference value.

Abstract: An electric motor control system includes a motor control circuit for generating a motor control signal and a braking mechanism for adjusting the motor control signal to augment motor losses when the motor control circuit is in a braking mode. The braking mechanism includes a difference component for receiving a first signal containing motor reference speed information, for receiving a second signal containing actual speed information, and for generating a third signal containing information indicating a difference between the reference speed and the actual speed. An integrating component integrates the third signal and generates a fourth signal representing the integrated third signal. The fourth signal may augment a voltage control signal in a voltage-based control circuit or may augment a flux-producing component of a current control signal in a current-based control circuit. The electric motor control circuit may include multiple braking mechanisms for use in different modes of operation.

Abstract: Provided is an electric motorcycle including a traveling motor, and a power supply circuit of an inverter and the like, in which a non-conducting cooling oil is supplied to be brought into direct contact with at least one of an electromagnetic coil of the traveling motor and a circuit board of the inverter. A radiator is disposed outside cases of a power plant and a power control controller so as to allow a traveling wind to pass by. Cooling oil is circulated between the radiator and a case of at least one of the power plant and power control controller. A cooling structure for an electric motor and the like that can obtain a higher cooling efficiency than a conventional art while having a simple structure which hardly causes increases in size, weight, cost, and the like can be provided.

Abstract: There are provided a back electromotive force detection circuit and a motor driving control apparatus using the same. The back electromotive force detection circuit includes a duty determining unit and a delay compensation unit. The duty determining unit outputs a differential level according to a duty of a driving control signal of a motor. The delay compensation unit performs delay compensation differently on each differential level to compensate for a delay in back electromotive force of the motor regardless of a variation in a duty of the driving control signal.

Abstract: Provided is a sample positioning technology wherein micro-vibrations of a top table on which a sample is placed are suppressed such that the quality of an image to be observed or the precision of a measured dimension value can be improved. A sample positioning apparatus according to the present invention is provided with an active brake for stopping the top table, an inner frame which surrounds the active brake, an outer frame which surrounds the inner frame, and actuators for driving the active brake. The actuators, after driving the active brake to stop the top table with respect to a stage, press the outer frame to adjust the position of the top table.

Abstract: The invention realizes a method for controlling an electric cylinder and a control system for the cylinder that can prevent a load for pressurizing from significantly exceeding a target load and can shorten the time for the pressurization. A servo controller 17 can set the speed of the rod 11 and a load for stopping Ps that is used for determining whether the rod 11 should be stopped so that the load for pressurizing Pm does not significantly exceed the target load Pt. The servo controller 17 drives the rod 11 under the position control mode and determines whether the load for pressurizing Pm that is detected by a load detector 13 is bigger than or equal to the load for stopping Ps.

Abstract: A feedback system for controlling a servo motor comprising at least one rotary angle sensor and at least one rotary speed sensor, wherein the rotary angle sensor supplies a measured rotary angle value to a computer, wherein the rotary speed sensor supplies a measured rotary speed value to the computer, the actual rotary speed values are the measured rotary angle values interpolated according to the integrated measured rotary speed values, and wherein at high rotary speeds, the actual rotary speed values are the calibrated measured rotary angle values, differentiated with respect to time, and at low rotary speeds, the actual rotary speed values are the measured rotary speed values.

Abstract: Methods and systems for robot and cloud communication are described. A robot may interact with the cloud to perform any number of actions using video captured from a point-of-view or in the vicinity of the robot. The cloud may be configured to extract still frames from compressed video received from the robot at a frame rate determined based on a number of factors, including the robot's surrounding environment, the available bandwidth, or actions being performed. The cloud may be configured to request that a compressed video with higher frame rate be sent so that the cloud can extract still frames at a higher frame rate. Further, the cloud may be configured to request that a second compressed video from a second perspective be sent to provide additional environment information.

Abstract: An ultrasonic motorized stage includes a base part, first and second tables, first and second linear ultrasonic motors which respectively drive the first and the second tables, and first and second optical linear sensors which respectively detect the amount of move of the first and the second tables. The first and the second linear ultrasonic motors and the first and the second optical linear sensors are arranged in positions, which are at sides other than the front side of the ultrasonic motorized stage and prevent wear debris generated when the first and/or the second linear ultrasonic motor is driven from affecting the first and the second optical linear sensors, so that the first and the second linear ultrasonic motors and the first and the second optical linear sensors do not protrude upward from the upper surface of the second table.

Abstract: Disclosed is a method for controlling an electro-mechanical brake system including a cascade controller, in which a position controller, a speed controller and a current controller are integrated to control a motor. The method includes determining whether an actual speed of a motor exceeds a command speed of the motor in an early stage of a motor operation; and restricting speed reduction of the motor until a braking force is generated if the actual speed of the motor exceeds the command speed of the motor in the early stage of the motor operation. Speed reduction of the motor is restricted until braking force is generated even if a speed error (actual speed of the motor>command speed of the motor) occurs in the early stage of the motor operation in the EMB system, thereby improving the braking responsiveness.

Abstract: Methods and systems for detecting an angular position of an electric motor are disclosed, including sending an electrical pulse through a stator coil of the electric motor, determining an approximate angular position of a rotor of the electric motor in response to detecting an timing of a returning electrical pulse from the stator coil, the timing of the returning electrical pulse being indicative of the angular position of the rotor; and determining an accurate position of the rotor in response to sensing a transition of a digital sensor in response to the rotor rotating relative to the stator, the transition being indicative of the accurate position.

Abstract: A motor and a method for serves finding the position of an armature in relation to a stator of the motor.

Abstract: Methods and systems are provided for driving one or more force coils. A system for driving force coils is provided including a PWM drive coupled to a first coil and a linear drive coupled to a second coil. The PWM drive efficiently drives the first coil to apply a first force. The linear drive drives the second coil to apply a second force that is substantially noise-free. The first force is greater than the second force.

Abstract: A fan motor control device comprises a clock signal generator and a drive unit. The clock signal generator generates a low-frequency clock signal. A frequency of low-frequency clock signal is less than 23 KHz. The drive unit converts the low-frequency clock signal to a high-frequency drive signal and outputs the high-frequency drive signal to drive the fan motor. A frequency of the high-frequency drive signal is higher than 23 KHz.

Abstract: A common electrode plate formed on a common electrode base attached to the lower surface of the movable stage faces a split electrode plate formed on a split electrode base attached to the upper surface of a main base, which are apart from each other at a predetermined interval. A support mechanism formed of ball bearings, ball stoppers at the movable side, steel balls, ball stoppers at the fixed side, and ball bearings allows the movable stage to move in directions of the X-axis, Y-axis and turning. A linear actuator 19 is driven to move the movable stage in the directions of X-axis, Y-axis, and turning.

Abstract: A fixed-position stop control apparatus (10) includes: a move-instruction generating means (22) for generating a move instruction for each control cycle; a position loop control means (25) for position controlling a rotation shaft (61) for each control cycle according to the move instruction generated by the move-instruction generating means; and a speed loop control means (35) for speed controlling the rotation shaft according to one of a speed instruction generated by a higher level control apparatus (45) and a predetermined speed instruction, thereby switching the speed control of the rotation shaft by the speed loop control means to the position control of the rotation shaft by the position loop control means. In this fixed-position stop control apparatus, the move instruction generated by the move-instruction generating means has acceleration smaller than the acceleration corresponding to the acceleration and deceleration ability of the rotation shaft.

Abstract: An alignment apparatus which moves a object comprises a first structure having a holding member which holds the object, a second structure having a magnet which constitutes a linear motor, the linear motor drives the first and second structure, and a flow passage formed between the holding member and the magnet.

Abstract: To provide a cooling structure which can effectively cool a controller for controlling a drive of a motor in an electric vehicle. A controller cooling structure of an electric vehicle is provided with a motor for supplying power to the rear wheel as the drive wheel, a motor driver for controlling a drive of the motor and a cooling plate for circulating the cooling water into the internal side of the motor driver in order to cool the same. In this controller cooling structure, one surface of the cooling plate is arranged adjacent to the motor driver and the other surface of the same is arranged adjacent to the rear swing arm.

Abstract: A self-diagnosing system for an encoder. The system includes an encoder circuit for outputting information detected by an encoder; a data preparing section provided in the encoder circuit and preparing data representing a state of an abnormal-state judgment factor in connection with at least one of the encoder and an electric motor combined with the encoder; a signal generating section provided in the encoder circuit and generating an abnormal-state signal when the data prepared in the data preparing section represents an abnormal state of the abnormal-state judgment factor; and a storage section provided in the encoder circuit and storing the data representing a state of the abnormal-state judgment factor when the signal generating section generates the abnormal-state signal. The storage section may store the data prepared in the data preparing section at a desired timing not later than the instant the signal generating section generates the abnormal-state signal.

Abstract: An actuating system having an electric motor that is controlled by a computer as a function of a setpoint position of a member that is to be actuated. The actuating system includes an encoder that is dependent on the movement of the motor, a sensor designed to deliver two square digital position signals in quadrature and which are representative of the position of the encoder, a device for processing the signals and which can determine the actual position of the encoder, and a device for comparing the actual position of the encoder with the position of the encoder that corresponds, in theory, to the applied setpoint. The actuating system can be used to actuate a member and/or actuate a device that meters the amount of fuel provided to a heat engine.

Abstract: The invention provides an active mass damper by use of which a machining apparatus can be downsized. The active mass damper includes a support unit for supporting a weight movably and horizontally, a motor for driving the weight, and a controller for controlling the motor. A torque command signal to be given to a motor of an X-table and a torque command signal to be given to a motor of a Z-table are put into the controller of the active mass damper so that the motor for driving the weight can be driven by feed-forward control using the torque command signals and feedback control based on the displacement of the weight.

Abstract: An apparatus and a method for adjusting components of an optical system, the components including an adjustment device. An electric positioning motor can be engaged onto the adjustment device of the components. An electrical generator is electrically connected to the positioning motor. The generator can be manually operated using an operating element, thereby effecting an adjustment of the component.

Abstract: A DC motor control method and apparatus for reducing time required for deceleration without degrading positioning accuracy. In a device which drives a mechanism by using a DC motor as a power source, in deceleration of the DC motor, when the mechanism arrives at a predetermined position, a velocity command value to the motor, generated in accordance with a cubic function having a mild curve profile, is changed to a constant value, thus the velocity is discontinuously reduced.

Abstract: Parameter set 1: T1a, T2a, Fa, Aa, parameter set 2: T1b, T2b, Fb, Ab, and parameter set 3: T1c, T2c, Fc, Ac, which consist of parameters having discrete values in three stages (large, medium and small) are prepared in the memory for example of the CNC 1 or the personal computer 3. For a given parameter set, the set giving priority to accuracy (S=0) is indicated by P (T1p, T2p, Fp, Ap), while the set giving priority to speed (S=1) is indicated by Q (T1q, T2q, Fq, Ag), and interpolation is performed and the parameter set Y=(1−S)×P+S×Q is obtained. The CNC 2 creates operating commands based on set Y and outputs these to the servo control section 2.

Abstract: A method of and system for directional drilling reduces the friction between the drill string and the well bore. A downhole drilling motor is connected to the surface by a drill string. The drilling motor is oriented at a selected tool face angle. The drill string is rotated at said surface location in a first direction until a first torque magnitude without changing the tool face angle. The drill string is then rotated in the opposite direction until a second torque magnitude is reached, again without changing the tool face angle. The drill string is rocked back and forth between the first and second torque magnitudes.