Abstract: A positioning system in which a absolute sensor detection signals are communicated to a controller, which is a personal computer, via a PC card. The PC card is provided with sensor connection terminals, a converter for converting sensor detection signals to digital position signals, PC connection terminals, a sensor drive circuit, and a switching circuit. The sensor switching circuit switches sensor connection terminals in accordance with commands from the personal computer, whereby one absolute sensor is excited or driven by the drive circuit, and detection signals from that sensor are converted to digital position signals that are fed to the personal computer. Using a PC card thus configured makes it possible to readily configure a positioning system having a plurality of absolute sensors.

Abstract: An analog-to-digital converter including a first module of the type having a series of processor stages, each of the stages performing two conversions of the signal output by the preceding stage, firstly an analog-to-digital conversion and secondly a digital-to-analog conversion, followed by subtracting the signal obtained from the output signal of the preceding stage to provide the analog output signal of the stage. The first module further assembles together the signals digitized by each stage (S1, . . . , Si) so as to provide an assembled digital signal (SN(nT) which represents the input signal (e(nT) of the converter in digital form.

Abstract: In a calculation processing device of a resolver signal, a processing speed of the resolver signal is increased, and a noise-proof characteristic thereof and also reliability thereof are improved, while total system cost is reduced. The resolver signal calculation processing device is arranged such that a resolver signal output from a resolver is digitally converted by a resolver interface into a digital rotary angle signal; the digitally-converted rotary angle signal is processed by a central calculation processing unit; and the resolver interface is provided within the resolver signal calculation processing device.

Abstract: A wireless local loop apparatus and corresponding system having an improved DAC operable at higher speed than heretofore achievable which exploits the sigma-delta principle in a different way. More particularly, the invention comprises a wireless local loop terminal (302) and corresponding system (300) that implement a digital-to-analog conversion circuit (105) including a storage means (110), such as a read only memory, for storing delta-sigma analog sequences corresponding to all possible values of a digital input (106) coupled to a plurality of one-bit digital to analog converters (120, 122, 124, 126). Each of the digital-to-analog converters (120, 122, 124, 126) are clocked by multi-phase clocks, such that each phase applied to each one of the digital-to-analog converters (120, 122, 124, 126) is delayed with respect to one another by the oversampling period.

Abstract: According to an embodiment of the present invention, an input signal is provided to an oscillator, which creates a count signal with a greater frequency than the input signal. The input signal triggers the oscillator to oscillate depending on the value of the input signal. The oscillator output is provided to a counter, which counts the number of oscillations undergone by the oscillator during a single period of the input signal or a number of periods of the input signal, whichever is desired. Since the oscillator frequency is greater than the frequency of the input signal, the oscillator effectively acts like a clock to time the input signal; the counter effectively acts to record the ‘time’ measured by the oscillator (clock). More formally, the counter generates a count value based upon the width of the input signal pulses. The counter output is provided to a decoder, which interprets the count generated by the counter.

Abstract: A multi-function type absolute converter comprises a sensor I/O port having a plurality of sensor connection terminals that can be connected to a plurality of absolute sensors, a conversion circuit for converting absolute sensor detection signals input via the sensor connection terminals to digital position signals, a PLD that can perform prescribed processing on the digital position signals thus generated, a host I/O port having output terminals for outputting the digital position signals and signals generated by the programmable logic device, a switching circuit for switching sensor connection terminals, and a control circuit for controlling each part, the control circuit comprising mainly a CPU, ROM and RAM. The inclusion of a PLD enables the multi-function type absolute converter to be flexibly adapted to user specification.

Abstract: Resolver systems are described that generate an estimate &phgr; of a rotatable member's position angle &thgr; and provide fault signals which monitor the reliability and accuracy of the estimate. The fault signals are formed from a monitor signal which multiplies resolver and estimate signals to derive information on the absolute and relative levels of resolver sense signals. At least one fault signal is formed from a loop error signal of the system servo loop. The fault signals report on, for example, mismatched sense signals, out-of-range sense signals and loss of position tracking to thereby enhance accuracy and safety in various resolver applications.

Abstract: A frequency estimator for estimating the frequency of a digital input signal (x(k)) includes a phase detection device (2) for determining the phase (&phgr;(k)) of the input signal (x(k)), a differentiator (3) for generating the phase difference (&phgr;diff1(k)) between adjacent samples of the phase (&phgr;(k), &phgr;(k-1)) and a filter (4) for averaging the phase difference (&phgr;diff(k)) and having a trapezoidal pulse response (hM(k)). The trapezoidal pulse response (hM(k)) is generated by superimposing a first triangular pulse response with a second triangular pulse response which is offset in time with respect to the first triangular pulse response.

Abstract: An analog computation system which forms a hybrid between analog and digital computation. The analog signal is divided into a plurality of separated analog signals, each of the different analog signals collectively representing the original analog signal, and each having less resolution then the total desired resolution. A number of different analog computation elements carry out a mathematical function on the separated signal. Different stages may be provided, and a signal restoration device may be provided between the different stages.

Abstract: A resolver system and method is provided for determining the angle position of a shaft. The resolver system includes a resolver having first and second output windings and an input or reference winding spaced apart from the first and second output windings, where either the input winding or the output windings are connected to the shaft. When a drive signal is introduced into the input winding, it generates first and second output signals on the output windings representing the angle position of the shaft. The resolver system of the present invention further includes a processor connected to the output windings for receiving the first and second data signals from the resolver and determining the angle position of the shaft. For generating the drive signal, the resolver system further includes a drive circuit connected to the input winding of the resolver. The drive circuit generates a pulsed drive signal for input into the resolver.

Abstract: There is provided an R/D converter capable of realizing a high speed response. When a sine wave for excitation of a resolver is a positive (or negative) maximum value, an AD converter makes AD conversion of a sine-wave output and a cosine-wave output of the resolver and makes input to a DSP. The DSP calculates on the basis of the input data, and outputs an obtained digital value to a DA converter and the like. Since the DSP calculates a rotor shaft angle, as compared with prior art (R/D converter of a tracking system) which includes a close loop made up of a demodulator circuit, a voltage controlled oscillator, and the like, and carries out a kind of PLL control, it becomes possible to carry out rotor shaft angle calculation at higher speed, and the high speed response can be realized by this.

Abstract: There is provided an R/D converter which can make high speed response. When a sine-wave for excitation of a resolver has a positive (or negative) maximum value, an AD converter performs AD conversion of sine-wave output and cosine-wave output of the resolver and makes input to an FPGA. The FPGA calculates on the basis of the input data, and outputs an obtained digital value to a DA converter and the like. Since the FPGA calculate the rotor shaft angle, as compared with the prior art (R/D converter of a tracking system) for performing a kind of PLL control including a close loop made up of a demodulator circuit, a voltage controlled oscillator, and the like, it becomes possible to perform rotor shaft angle calculation at higher speed, and by this, the high speed response can be made.

Abstract: The method consists of the adding of a dither signal of constant amplitude, frequency-modulated by noise, to the signal applied to the input of the converter. An automatic control link is set up between the level of the added interference signal and the signal applied to the input of the converter so that the level of the input signal added to the level of the added interference signal is equal to the level of the full scale signal of the converter. Application to digital communications radio receivers.

Abstract: A method of decoding a quadrature encoded signal where position tracking is implemented which decouples the position calculations from the encoder edges. In one embodiment of the present invention, a uni-directional pulse accumulator is used to count encoder edges, and a periodic interrupt timer is used to update the position information, where interrupts are generated independent from encoder edges. At slow speeds, the mode switches to monitor each encoder edge to check for direction reversal without requiring position information. This decodes bi-directional quadrature position information using a uni-directional counter and a count compensation method for resolving changes in direction.

Abstract: A moving target opposite a stationary analog sensor has two sensitive elements delivering two sinusoidal output signals, of equal maximum amplitudes, centered on the same average value, in quadrature and with a period equal to one revolution of the target. A device for processing the two output signals, generates n output signals in-parallel, where n is a positive whole number greater than or equal to 2, for providing the position of a rotating component, connected to the moving target, with a resolution equal to 2n. The processing device includes a generator device, a detection device, a multiplexing device and an interpolation device.

Abstract: It is an object of this invention to provide a digital conversion method for an analog signal in which, when sin(&thgr;−&phgr;) is calculated as a error deviation &egr;, a first output signal sin(&thgr;−&phgr;)·f(t) of the previous stage of the error deviation &egr; is converted into a digital signal by positive/negative sign determination performed by a comparator to make almost circuits into digital circuits, thereby making it easy to form an IC. In the digital conversion method for an analog signal according to the invention, sin(&thgr;−&phgr;)·f(t) obtained by guiding the rotation detection signal to a multiplier and operating the rotation detection signal is converted into a digital signal by positive/negative sign determination performed by a comparator to achieve a stable and inexpensive configuration.

Abstract: The present invention is directed to a method and apparatus which utilizes a software-based digital signal processing circuit to generate a signal which is representative of the status of a movable component. A preferred embodiment of the apparatus of the present invention includes a synchro which is connected to a movable component. An analog reference excitation may be applied to the synchro, and the synchro generates analog synchro signals which bear a relationship to the status of the movable component. The analog synchro signals are converted to digital synchro signals by a plurality of analog-to-digital converters. A digital reference signal and the digital synchro signals are provided to a software-based digital signal processing circuit which preferably corrects constant and time-varying errors in the digital synchro signals and generates a status signal which is representative of the status of the movable component.

Abstract: An encoder interpolation circuit for obtaining interpolation data within one wave from two sine-wave encoder signals of different phases comprises interpolative computation means (2) for receiving two sine-wave encoder signals received and carrying out to interpolative computation within one wave, signal deviation detecting means (3) for detecting a deviation of the two sine-wave encoder signals, correction data forming means (4) for outputting correction data corresponding to the detected deviation and the output of the interpolative computation means, and corrective computation means (5) for obtaining the corrected interpolation data by carrying out corrective computation for the output of the interpolative computation means with the correction data and obtaining corrected interpolation data.

Abstract: A position measuring system for the determination of the relative positions of two objects which can be moved with respect to each other, as well as a process for operating the same are disclosed, which in case of a relative movement provides at least one pair of phase-shifted analog incremental signals, and which makes possible a definite variation of the signal periods (SP) by at least one signal period variation factor (n) of the analog incremental signals transmitted to an evaluation unit arranged behind it by a signal period variation unit. The signal period variation unit furthermore comprises correction means for eliminating most varied errors in the output signals (SIN', COS'). Among these are counted errors possibly resulting during the signal period variation, as well as measurement arrangement-specific errors.

Abstract: The present invention is directed to a method and apparatus which utilizes a software-based digital signal processing circuit to generate a signal which is representative of the status of a movable component. A preferred embodiment of the apparatus of the present invention includes a synchro which is connected to a movable component. An analog reference excitation may be applied to the synchro, and the synchro generates analog synchro signals which bear a relationship to the status of the movable component. The analog synchro signals are converted to digital synchro signals by a plurality of analog-to-digital converters. A digital reference signal and the digital synchro signals are provided to a software-based digital signal processing circuit which preferably corrects constant and time-varying errors in the digital synchro signals and generates a status signal which is representative of the status of the movable component.

Abstract: A variable reluctance resolver wherein the sine and cosine values are processed to obtain digital values for position with an accuracy similar to that of a conventional resolver. The variable reluctance resolver is driven at a constant speed and the incremental digital values are recorded and processed to extract the fundamental through a Fourier transform. The Fourier transform of the fundamental is compared to the original values from the variable reluctance resolver to provide a look up table of correction values.

Abstract: A signal analysis system for processing quadrature analog waveforms from an encoder. High-resolution position measurements for external measurement devices are obtained. A hardware component receives the quadrature analog signals from the encoder and processes these signals to generate low and high-resolution waveforms. These waveforms are then further processed and sent as first and second data streams to a computational component of the signal analysis system. The absolute phase angle (.THETA.) of the encoder's analog signal is determined by processing the data streams with the computational component. .THETA. is compared to a series of calibration factors to determine the position of the translating component of the external measurement device.

Abstract: A resolver to digital converter wherein the data from the resolver is processed according to octants which provide the most significant three bits indicating shaft position. The sine and cosine values from the resolver are further processed according to the octant with the smaller value being divided by the larger value to derive a tangent value in the range of zero to one. A look up table can then be used to provide a linear position indication from the tangent values which are then added to the octant value to obtain the shaft position indication.

Abstract: An interpolation circuit of an encoder of which dynamic accuracy is improved is disclosed. The phase angle data detecting circuit 1 detects to store the phase angle data PH for each of the first clock CK1. The phase angle data PH is input to the updating circuit 2 in which the current data CNT is subtracted from the subsequent phase angle data PH so as to be updated. The differential data DX is limited within an upper limit to be added to the current data CNT. The integrating circuit 3 integrates the differential data DELTA1, whose upper limit is predetermined, by the second clock CK2 to generate the carry signal QUADEN at each timing when the integrated value leads to the period ratio of CK1 to CK2. The two-phase square wave generating circuit 5 generates two-phase square wave signals at each timing of the carry signal QUADEN. The over-speed detecting circuit 6 monitors the differential data DX to generate the over-speed alarm signal OSALM under a predetermined condition.

Abstract: A displacement amount detection apparatus detects the displacement amount of an object by utilizing two input signals which have a predetermined phase difference therebetween and are output in correspondence with a displacement of the object. The apparatus includes an amplifier which can arbitrarily set the amplification gains of the input signals, and a gain memorizer for dividing the two input signals obtained upon displacement of the object over a predetermined displacement range of the object into a plurality of displacement periods, and for memorizing the partial amplification gains of the amplifier in units of displacement periods on the basis of signals in the respective displacement periods. In addition, a controller selects the gains memorized in the gain memorizer and sets the selected gains in the amplifier when the amplifier amplifies the two input signals.

Abstract: A digital angle detecting method adapted to obtain a stable digital angle output, which is little affected by cable length, uses a resolver of the amplitude modulation type. The respective phases of two-phase resolver signals are first shifted, and are then added to the original two-phase synthetic signals. Subsequently, another signal is synthesized by multiplying the two synthetic signals by two-phase sine-wave signals. Finally, an angle output and an angular velocity output is obtained by using the synthesized signal.

Abstract: A position sensor is provided with a displacement signal output circuit 1 that amplifies an electromagnetically induced and detected current signal from a slider and converts the result to a rectangular wave signal; a phase difference detection circuit that compares the output signal from the displacement signal output circuit with a clock signal employed for producing the alternating current component from the scaler and detects the phase difference; and an interpolation pulse counter that determines digital displacement data from the phase difference detected at phase difference detection circuit using interpolation pulses. Further, an averaging circuit is provided at the output stage of this interpolation pulse counter which calculates and outputs an average value of a plurality of instances of digital displacement data successively calculated by the interpolation pulse counter.

Abstract: An apparatus and method for generating digital electrical signals which are representative of the angular position and rotational velocity of a rotatable shaft component in a servomechanism includes a resolver which is connected to the rotatable component. The resolver generates analog electrical output signals which are representative of an excitation signal modulated by both the sine and cosine of the electrical angular or position of the motor. The output signals from the resolver are fed to a digital signal processing circuit which employs software algorithm techniques to define a plurality of tasks which are implemented sequentially to obtain the desired angular position and velocity signals. First, the sine and cosine signals are read from the resolver through respective analog-to-digital converters. The sine and cosine signals are demodulated by multiplication with the excitation signal, and the undesired higher frequency components are deleted by filtering.

Abstract: The encoder provided by the present invention computes an obtains a difference value between a maximum value and a minimum value of a simulated sinusoidal signal from the signal detecting section, computes an amplitude of said simulated sinusoidal signal in the amplitude computing section according to the difference value, decides an optimal reference voltage for an A/D converter or an optimal amplification factor and an optimal reference voltage for a signal amplifier for simulated sinusoidal signals, and sets a reference voltage for the A/D converter or an amplification factor and a reference voltage for the signal amplifier according to the optimal values.

Abstract: In an encoder unit for interpolating analog signals such as sine waves and triangular waves to obtain higher resolution or absolute values through A/D conversion and arithmetic processing, a delay time of data which is caused by A/D conversion and arithmetic processing time is eliminated to prevent deterioration of control performance. A storage unit for holding detected angular data and an output compensation unit for compensating the delay time are provided and a position change occurring during the delay time is predicted by the output compensation unit from angular data obtained from current and previous sampling cycles, and the delay time is compensated by adding the predicted position change to the current sampling data. Deterioration of the control performance can be prevented and inexpensive low-speed A/D converter and arithmetic processor can be used, and, therefore, required costs can be reduced.

Abstract: Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(.omega.t .+-.d.+-..theta.), sin(.omega.t.+-.d-.theta.)) are electrically synthesized which have electric phase angles (.theta.) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. ".+-.d" here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change. In the synthesized two signals, the phase variation errors (.+-.d) appear in the same direction, while the phase differences (.theta.

Abstract: A software-based resolver-to-digital converter (RDC) (80) for computing an angle of rotation .THETA. of gimbal-mounted instrumentation (16) in a gimbal system. The RDC (80) computes the angle of rotation of the instrumentation using parameter signals received from a resolver (32) in the system. The parameter signals, along with a resolver reference signal are input into a multiplexor (60) and are multiplexed. The signals are then fed to an analog to digital converter (38) and converted to digital form. The digital signals are then input into a processor (36) associated with the system. This processor, in addition to performing numerous system computations, is programmed through appropriate software to filter the digital signals received, compute the value for the angle of rotation .THETA. and output the computed value to system circuitry (31) for processing to enhance system operation.

Abstract: An apparatus and method for generating digital electrical signals which are representative of the angular position and rotational velocity of a rotatable shaft in a servomechanism includes a resolver which is connected to the rotatable component. The resolver generates analog electrical output signals which are representative of an excitation signal modulated by both the sine and cosine of the electrical angular position of the motor. The output signals from the resolver are fed to a digital signal processing circuit which employs software algorithm techniques to define a plurality of tasks which are implemented sequentially to obtain the desired angular position and velocity signals. First, the sine and cosine signals are read from the resolver through respective analog-to-digital converters. The sine and cosine signals are demodulated by multiplication with the excitation signal, and the undesired higher frequency components are deleted by filtering.

Abstract: A synchronizing device for a parallel connection of a synchronous generator and an a.c. network. The device includes a measuring circuit for measuring the voltage and frequency of the generator and the a.c. network and for measuring the phase angle between the generator and the a.c. network. The measuring circuit includes control outputs for regulating the rotational speed of the generator drive. A set value for the generator frequency includes a defined slip at the start of balancing. The measuring circuit also regulates the voltage output of the generator to match the a.c. network voltage. Once the phase angle between a.c. network voltage and generator voltage has fallen below a predefined value, null balance occurs.

Abstract: A method and an arrangement for reducing the influence from distortion which is produced when an electrical signal, which is divided into two components, is converted from analogue to digital form. The signal is divided in a phase detector in which it is phase detected with respect to two reference signals, phase shifted 90.degree. with respect to each other. The two components are frequency coded by the reference signals which are provided with a periodic frequency sweep. After the conversion into digital form, each of the components are frequency decoded so that they, with respect to frequency, appear as narrow band signals while possible harmonics which are part of the distortion, are distributed over a frequency range defined by the size of the periodic frequency sweep.

Abstract: An electrical system for converting a magnetic azimuth detector (MAD) signal into a corresponding digital signal. A conversion circuit receives a three-wire signal from the MAD; the three-wire signal is proportional to an angle .theta., which indicates the position of the MAD relative to magnetic north. The conversion circuit converts the three-wire signal into sin .theta. and cos .theta. signals. A digitization circuit converts the sin .theta. and cos .theta. signals into corresponding digital signals by first half-wave demodulating the analog sin .theta. and cos .theta. signals, then low-pass filtering the signals to extract the DC components, and finally digitizing the analog DC components.

Abstract: An angle of rotation detector has a drive unit which supplies 90 degree phase shifted signals to a pair of stator coils and measures an analog output from a rotor coil in a resolver. A calculating device calculates the rotational angle of the resolver using the output of an analog to digital converter receiving the analog output of the rotor. In one embodiment, the calculating device performs a Fourier transform to compute the phase of a fixed frequency component contained in the output of the rotor coil. In another embodiment, the drive unit supplies signals wherein f(T/2+t)=-f(t) and the calculating device performs a Fourier transform using data from successive half periods of the drive waveform. In another embodiment, the output of the rotor is sampled at 1/4 period of an excitation signal from the drive unit and the calculating device determines the phase difference between the excitation signal and the rotor output.

Abstract: A dual phase resolver to digital converter having two separate channels for generating rotor position data. The first channel generates an indication of rotor position based on a sinewave type reference signal applied to a first stator winding and the rotor signal while the second channel provides an indication of rotor position based on a cosinewave type reference signal applied to the second stator winding and the rotor signal. Logic circuitry associated with the data channels provide separate fault data indicative of when position data may be subject to error. The data from the two channels are selectively combined in the output of the converter. Data from one channel is used when the other channel is subject to fault. An average of the data is used when both channels are operating properly in order to provide greater accuracy.

Abstract: A variable reluctance resolver comprises a rotor core and stator magnetic poles structured to enable reluctance in the space between the rotor core and stator magnetic poles to be changed by the positions of the rotor core and to make the fundamental wave component of the reluctance variation N cycles per revolution of the rotor core, N being an integer of 1 or more; first magnetic poles having a predetermined number 3N phases arranged at equal intervals on the stator magnetic poles; second magnetic poles having a predetermined number of 3N phases formed in the central positions between the first magnetic poles; excitation coils arranged individually between the first and second magnetic poles and connected in series to each other for each phase of the magnetic poles; a current change detecting device for detecting current value change due to the variation of the reluctance when an alternating current is applied to the magnetic coils of each phase of the magnetic poles; 3N difference value calculating devices

Abstract: A resolver system includes a resolver having an annular rotor, and an annular stator arranged around the annular rotor in spaced relationship thereto. The rotor and the stator are arranged such that the reluctance of a space defined between the rotor and the stator varies with a change in the angular position of the rotor in such a fashion that one revolution of the rotor causes one cycle of a fundamental frequency component of variation of the reluctance.The stator has formed thereon a plurality of pole shoes circumferentially arranged at intervals of 120.degree. or 60.degree. to form three of six phases, each of the pole shoes having a single kind of winding wound thereon. A servo driver applies an excitation signal to each of the windings on the pole shoes of the stator to excite same.

Abstract: An apparatus, preferably in the form of a resolver to digital converter for converting the amplitude modulated, encoded signals into digital signals representative of the velocity and position is described. The apparatus is of the type that includes an electronic control transformer circuit for providing respective products of sine and cosine analog signals respectively times the cosine and sine of the digital position signals and for differencing the products so as to produce an analog AC error signal. The improvement comprises means for converting the analog AC error signal into a digital DC error signal and a digital accumulator for time integrating the DC error signal to generate the digital position signal. In a preferred embodiment the output of the accumulator is digitally modulated so as to provide the digital position signal as a bit-reduced feedback signal to the electronic control transformer.

Abstract: A phase compensation circuit for use with a resolver circuit that compensates for resolver angle measurement error without the use of special compensation windings on the resolver or the buffer amplifier associated with the compensation windings. With the present invention, primary windings from a plurality of resolvers may be reduction over conventional circuits. A digital computer is employed to process integrated data indicative of the phase shift of signals generated by the resolver, and compute error correction signals that compensate sine and cosine angle data output signals of the resolver. No resolver compensation windings are necessary and no additional electronic equipment is necessary. The present invention provides increased accuracy to fulfill more stringent angle measurement specifications.

Abstract: A method of correcting quadrature signal errors comprises the steps for generating an error function signal E by summing the squares of the quadrature signals and subtracting a constant K therefrom, saving the value of the error function E at .theta. equals approximately 0, .pi./2, .pi., and 3.pi./2, using the saved values of the error function to generate signals indicative of the quadrature errors, and generating corrected quadrature signals by processing the quadrature signals to eliminate the errors.

Abstract: An absolute position encoder for detecting the position of a moving object includes a coding part attached to the moving object which receives sinusoidal and cosinusoidal signals through channels. Each channel receiving signals having a different number of cycles from the other channels per unit of movement of the object. The signals received by each channel are converted to digital form by an analog to digital (AD) converter and stored in a ROM. Discrepancies between the sinusoidal and cosinusoidal phase are corrected digitally by comparing the digital results of the channels, adjusting the data from higher-order channels to conform to that of adjacent lower-order channels, and finally combining the data for each channel to obtain the absolute position of the moving object.

Abstract: A digital resolver is provided that accepts an analog representation of an angular or linear displacement within a reticle modulation cycle of a rotatable or translatable member, and provides a highly accurate output digital representation of the displacement within the cycle, even during rapid movement of the member. An encoder cooperative with the interpolator receives an analog signal that represents the displacement, and yields a pair of quadrature-phased sine wave signals accordingly. These signals are provided to the interpolator, wherein each is multiplied by a stored digital representation of a trigonometric function of the output digital signal. The resulting products are then added so as to provide an error signal which is used to drive a digital control loop, such that a digital output signal is provided that represents displacement within a reticle cycle.

Abstract: A method of interpolating between two signals comprising the conversion of each signal into digital form and use of the converted signals to address a memory device at each address of which is pre-stored the result of interpolation for a particular combination of values of the signals.One embodiment of the method resides in a shaft angle encoder having: sensor means regulated by an encoder disc to produce two analogue output signals, analogue to digital conversion means which convert the said analogue signals, a memory device in which the said results are pre-stored and memory addressing means which use the converted signals to cause corresponding pre-stored results to be output from the memory device.

Abstract: An ac encoded signal to digital converter suitable for converting ac synchro or resolver signals to a corresponding digital angle value. A synchronous demodulator including a high pass input filter and low pass output filter utilizes the associated reference excitation signal to convert the individual ac encoded signals to corresponding dc values. The absolute value of the dc values are proportional to the amplitude of each of the respective ac encoded signals, but the dc value is negative if the ac encoded signal is 180.degree. out of phase with the reference excitation signal. These dc values are subsequently digitized and digitally processed based on their trigonometric relationship to extract the encoded angular position value.

Abstract: An absolute encoder for detecting the absolute (as opposed to the relative) rotational displacement of an encoder shaft includes a pair of pitch signals recorded on tracks and an associated signal processing circuit. The pair of pitch signals have different periods (wave lengths) which are such that they have no common factors. The signal processing circuit includes magnetic sensors for producing absolute position data indicative of the degree of displacement of the encoder shaft, on the basis of the pitch signals. Through the use of a pair of pitch signals having periods with no common factor, a high degree of resolution is obtained, without having no significantly increase the number of pitch signal tracks.

Abstract: A motor feedback control system which in addition to a quantized digital position feedback value, uses a feedback signal which represents the error between the actual motor position and the quantized digital position. The error function is combined with the quantized digital position value to produce a digital position value with greater resolution. The combined value is differentiated to produce a velocity value for velocity feedback control of the motor.

Abstract: A software-based resolver-to-digital converter (RDC) (80) for computing an angle of rotation &THgr; of gimbal-mounted instrumentation (16) in a gimbal system. The RDC (80) computes the angle of rotation of the instrumentation using parameter signals received from a resolver (32) in the system. The parameter signals, along with a resolver reference signal are input into a multiplexor (60) and are multiplexed. The signals are then fed to an analog to digital converter (38) and converted to digital form. The digital signals are then input into a processor (36) associated with the system. This processor, in addition to performing numerous system computations, is programmed through appropriate software to filter the digital signals received, compute the value for the angle of rotation &THgr; and output the computed value to system circuitry (31) for processing to enhance system operation.