Abstract: The present invention provides a sensorless circuit for detecting rotational speed of a rotor in an induction motor. The circuit includes a switch between the AC source driving the motor and a motor phase winding. When the switch is closed, there is developed across the phase winding a voltage waveform from the AC source. When the switch is subsequently opened, there is developed across the winding a residual voltage waveform induced by the rotor. The speed of the motor is determined by measuring a time interval between selected points on the voltage waveform.

Abstract: In a circuit arrangement for measuring a starting of rotation of a generator having an exciting winding and three-phase windings, a voltage regulator regulates an output voltage of the generator by influencing an exciting current, the three-phase windings are connected to one another at a point, one of the phase windings is connected to ground via a first resistor, another of the phase windings is connected to ground via a second resistor, a voltage across the first resistor is evaluated as a rotational-speed-dependent alternating voltage, this voltage is compared with a threshold voltage, and the starting of the rotation of the generator is detected when the measured voltage exceeds the threshold voltage.

Abstract: A measuring method for vehicles equipped with an internal combustion engine, the engine including a starter battery and a driven staffer motor used when an attempt is made to start the engine, is disclosed. According to the method, a voltage across a measuring shunt inserted in a current circuit between the battery and the starter motor is repeatedly measured, at a sampling rate, during each revolution of a crankshaft of the engine during activation of the starter motor. Corresponding values of a current delivered from the starter battery to the starter motor are derived from voltage measuring results. Values of the current are registered in a memory of a measuring computer. The registered values are used to establish a status of the combustion engine and its starting system. A value of a derivative of a rotational speed of the combustion engine crankshaft is obtained from the registered values.

Abstract: A method of and an arrangement for rotary speed determination in an electric motor is used to determine an instantaneous motor rotary speed from an alternating portion of the current caused by switching on and off of the commutator with a recognizable periodicity. An endless auto-correlation sequence is formed, and the rotary value is determined from the distance between the maxima or minima of the auto-correlation sequence. In combination with a further method for rotary speed determination from the alternating portion of the current with the use of twice fourier transformations, a very reliable and error-free rotary speed determination is provided.

Abstract: An improved power system control apparatus which reduces power fluctuations and includes an estimated unit for estimating the system impedance and phase difference angle using the generator power transmission terminal voltage, the reactive power and effective power of the system. The invention enables accurate power system impedance estimates in a real-time manner. The invention can be applied to a filter device for removing noise components from an angular velocity signal. The filter device comprises first arithmetic means for calculating changes in phase angle, second arithmetic means for calculating changes in angular velocity, a first integrating for integrating the changes in the phase angle to obtain an estimated phase angle, a second integrator for integrated the changes in angular velocity to obtain an estimated angular velocity and a power stabilizing filter for filtering the estimated angular velocity signal.

Abstract: Endless web or drum type laser printers have enhanced copy registration. Image frame length control has particular utility in a printing or reproduction apparatus that writes one or more images on a photosensitive media that is driven by a low cost synchronous hysteresis A.C. motor. The power line frequency is monitored and compared to a precision crystal clock. When the frequency is lower than specification and the motor slows down the number of scan lines are increased by repeating them to lengthen the image frame. When the power line frequency is higher than specification, the number of scan lines per image frame are decreased by deleting scan lines to shorten the image frame.

Abstract: In a process and a device for measuring the rate of rotation of a rotating part which is completely enclosed by a housing, the current signal which is generated by the rotating part is subjected to two Fourier transforms after corresponding signal processing in digital form. The rate of rotation is determined from the spectrum obtained after the second Fourier transform. The rate of rotation is determined from the time pertaining to the maximum of the spectrum which is directly proportional to the rate of rotation.

Abstract: A method and system for sensing the rotor speed of a brushless permanent magnet motor wherein a signal containing isolated third harmonic components of the flux density is acquired, and the absolute values of the maximas of the signal are measured, the last measured absolute maxima representing the current rotor speed of the motor.

Abstract: The specification discloses an NRR (Non-Repeatable Run-out) measuring instrument for measuring the NRR of the rotating object motor to be measured without installation of a special attachment such as an encoder. In the NRR measuring instrument of the invention, encoder signals are obtained from back-electromotive forces developed at driving coils of the rotating object motor by removing spike noise thereof by LPF 30U, 30V, 30W and reformed by a wave shaping circuits 32U, 32V, 32W. The encoder signals together with digitized displacement signals generated by noncontact displacement measuring instrument 14 through A/D 28 are inputted to a CPU 34. In the CPU 34, sampled data are acquired from the digitized displacement signals being triggered by the encoder signals and the NRR is calculated based on the sampling data.

Abstract: An apparatus and method for automatically testing a safety light curtain used to protect to an unsafe moving part of an industrial machine. A combined beam splitter and photodetector is temporarily attached to the receiver of the light curtain with beam splitter in the path of one of the light beams. A portion of the light beam continues to a receiver of the light curtain and a diverted portion of the light beam illuminates a photodetector. Interruption of this particular light beam simultaneously triggers a safety system to initiate the stopping of the machine and triggers the photodetector. A motion detector temporarily coupled to a rotating part of the machine determines when the machine has stopped. This motion detector may include a d.c. tachometer coupled via a resilient friction wheel. A timer connected to the photodetector and the motion detector determines the duration of the interval between interruption of the one light beam and the stopping of the machine.

Abstract: A revolution counts detection apparatus comprises a detector for detecting the induced voltage of an electric motor, a capacitor for storing charges, and a charging means for charging the capacitor on the basis of the detected induced voltage. Further, a generator for generating a voltage corresponding to the revolution velocity of a revolving body can be used instead of the electric motor. Whereby, the revolution counts of the motor or the generator can be detected as a voltage across the capacitor.

Abstract: An RPM and voltage indicator is used to check the operating speed and voltage output of a generator set. The device is used to verify the proper operation of a generator set or any auxiliary power unit, such as a DC to AC invertor, and further functions as a tool to make necessary adjustments to a governor or frequency control of any such generator set or auxiliary power unit.

Abstract: An energizing and test circuit for a gyroscope spin motor which in addition o having a set of energizing coils, also includes a reference coil which generates a sinusoidal voltage whose frequency is a function of speed of rotation of the spin rotor. This signal is fed to a precision tachometer circuit whose output is compared with a desired speed signal for generating a voltage required to maintain a proper spin rate and comprises what is referred to as a "sustain" voltage. The sustain voltage is buffered and coupled to an external test point which can be monitored to determine the functional integrity of the gyro and more particularly the quality of its motor bearings. This sustain voltage is also coupled to drive amplifier circuit means which power the head coil assembly including drive windings of the spin motor. Circuitry is also provided for performing an automated spin-up and spin-down test.

Abstract: A variable capacitor whose capacitance is a function of shaft position is coupled to a rotating shaft. A constant voltage is applied to the capacitor. As the shaft rotates, the changing capacitance of the variable capacitance causes current to flow into and out of the variable capacitor in response to the shaft rotation--thus providing a current source with no inherent practical frequency response limitations. A transresistance amplifier converts the current to an output voltage which is proportional to instantaneous shaft velocity. Various arrangements are used to eliminate the discontinuity associated with the inherent sign change of the capacitance time derivative while retaining the signal components associated with instantaneous velocity changes of the rotating shaft.

Abstract: An apparatus for detecting the speed and position of a rotating shaft of an electrical motor. A commutator is provided having three or more poles. First and second brushes are provided in sliding contact with the commutator for supplying electrical power to the poles of the commutator. At least one of the poles is in electrical communication with the shaft. Rotation detection means measure the electrical potential difference between the shaft and ground and generate a rotation information signal in response to the changes in the electrical potential difference as the shaft rotates.

Abstract: Disclosed is a DC parameter motor tester based on current time response, which tester does not require coupling of the motor (14) to some mechanical device or measuring other noise sensitive parameters taken from only a few discrete data points. As is disclosed, the steady state speed of the motor is determined from the frequency composition of the commutation noise and ripple in the steady state current by performing a fast fourier transform on the steady state current to determine its power-spectral-density which shows the frequency composition of the steady state current waveform by giving the power in the waveform at each frequency. The frequency at which the most power exists is divided by the number or twice the number, depending upon the construction of the motor, of commutation segments in the motor to determine the motor's frequency of rotation or velocity at measured power input.

Abstract: An improved system is provided for accurately referencing the revolving motion of electric motors used as positioning devices, and is particularly applicable to the automatic positioning and repositioning of ground station antennas in the reception of satellite TV signals.The system utilizes the action of the positioning motor itself as a reference and involves the extraction and counting of variations in the form of pulses produced in the current within the motor as a result of pulses generated, during motor operation, by the commutation process. A low impedance source senses the motor current pulses and feeds them to an active lowpass filter which suppresses any high frequency noise produced during motor commutation. Peak following circuitry, including separate positive and negative peak detectors, detects and follows the positive and negative peaks of the motor current pulses and produces a pulsating output waveform which is proportional to the number of motor current pulses detected by the peak detectors.

Abstract: In a Stirling cryogenic refrigerator, the movement of the displacer is monitored by sensing the back EMF in the displacer drive coil throughout displacer stroke. The back EMF signal is applied through a feedback circuit to control the phase relationship of displacer movement with a reference signal related to the pressure wave.

Abstract: A control circuit and method for using the same in operating a power switch such as a relay, FET, etc., having conductive and nonconductive conditions and adapted to direct a high magnitude driving current from a power supply through an electric load circuit when the power switch is in the conductive condition. Such a power switch can be used to control small motors used extensively in motor vehicles. This control circuit comprises testing means for directing a low magnitude, low duty cycle testing current through the load or motor circuit while the power switch is in the nonconductive condition, sensing means for creating a control signal indicative of a predetermined electrical characteristic, such as current flow, in the load circuit, means for shifting the power switch into the conductive condition for energizing the load when the control signal from the sensing means has a predetermined value, i.e.

Abstract: A toy racing game accessory comprising a tachometer and fuel gauge. The tachometer includes a rack and pinion assembly which is driven by a linear actuator. A tachometer needle is coupled to the rack and pinion assembly. The action of the linear actuator is proportioned to the amplitude of current passing through the track rails and toy car motor as determined by a speed throttle. The fuel gauge includes a ratchet wheel. The rack and pinion assembly includes a pawl which advances the ratchet wheel if the tachometer needle is made to advance beyond a predetermined threshold speed. The ratchet pawl advances the ratchet wheel so as to cause the fuel gauge needle to advance towards "empty". The amount of advance of the fuel gauge needle depends on the swing of the tachometer. When the fuel gauge reads "empty" a cammed microswitch opens to cut off all power to the track rails and bring the racing car to a halt.

Abstract: A method of suppressing resonances in electro-mechanical servo systems is disclosed. The servo systems are of the type where first signals indicative of actual position of the servo system are differentiated and second signals indicative of the acceleration of the system are integrated. The differentiated signals are applied to the integrator in order to provide accurate initialization thereof. In modes of operation where the acceleration of the system is substantially zero, the differentiators are not used, thus decoupling the mechanical system from the electronic control system and eliminating resonance from the servo loop. The duty cycle of the differentiators is varied in differing modes of operation of the servo system so as to provide maximum bandwidth and speed to the system coupled with minimum errors in positioning. The system is described in connection with the servoing of magnetic read/write heads radially with respect to rotating magnetic disk data storage media.

Abstract: In a pulse-width-modulated servo motor control system, a signal indicative of the average terminal voltage of the servo motor is fed back to stabilize the response of the control system. Under normal conditions the feedback signal is representative of the velocity of the servo motor output shaft and thereby operates to stabilize the control system response as a function of the output shaft velocity. Under adverse conditions tending to increase the power supplied to a motor, the feedback signal increases in a manner to limit the power supplied to the motor and to maintain the control system bandwidth substantially constant.

Abstract: An electronic tachometer that includes an integrator for producing a speed signal by integrating a signal representative of acceleration of a body and a differentiator for producing a speed signal by differentiating a signal representative of the position of the body, the differentiator being formed by a passive RC circuit and operatively associated with circuitry for alternately supplying to the differentiator two signals representative of position, one of which is inverted so that signals of a single polarity are supplied to the differentiator, and further circuitry for connecting the differentiator output to the integrator feedback circuitry so as periodically to update or reset the speed signal produced by the integrator, which is formed by an operational amplifier having a capacitive feedback which is shunted by a resistor when the differentiator output is active to update the integrator.

Abstract: An improved electronic velocity measurement device for an accessing type disk drive combines a differentiated cyclically discontinuous displacement (position error) signal (PES) with integrated motor current signals to produce an accurate continuous velocity signal over the entire range of displacements of a linear actuator. Differentiation of the displacement signal is achieved by low bandwidth differentiator circuitry that is corrected for periodic reversal of the displacement signal by a unique fill-in signal derived from integrated motor current. In a specific embodiment, the fill-in signal is derived by the use of a second differentiator using a second displacement signal in space quadrature with the primary displacement signal.

Abstract: In a continuous electrolytic foil forming process employing a constant d.c. voltage power supply, the speed with which the foil is drawn through the electrolyte is automatically adjusted by a feedback mechanism to maintain a constant value of forming current. In this process, the speed of drawing the foil corresponds inversely to the potential capacity of the foil as it enters the electrolyte at any given time. This speed or equivalent capacity and the corresponding location of the foil is monitored and recorded during the continuous film forming process.

Abstract: An electronic multi-mode vehicle performance control system selectively provides a digital display of odometer, tachometer, speedometer readings as well as other vehicle performance parameters while avoiding the disadvantages of mechanical systems which are subject to frequent breakdown. Provision is made to signal the operator of the vehicle when a preselected maximum vehicle velocity or engine rpm is being exceeded and furthermore to signal the operator when the engine rpm drops below a preset minimum level with the consequent danger of engine stall. Other vehicle parameters such as total elapsed engine revolutions is also displayed. Also provided are digital speed limit setting means for presetting the desirable vehicle and engine speed limits.

Abstract: A speed detector for a direct current motor is coupled substantially in parallel with the motor such that only the motor input voltage and a function of the input current are inputs to the speed detector/indicator system. Analog speed detection is provided by using either operational amplifiers or single stage transistor circuits to sample the current and voltage to generate a voltage proportional to speed of the motor.

Abstract: A tachometer for measuring speed and armature position of a motor is disced whereby the counter electromotive force present in spikes on the power terminals are shaped, analyzed and displayed as tachometer information. The spikes occur as commutation takes place allowing a coarse angular armature shaft position to also be derived.