Power is provided to the stator windings of an AC machine which includes a component at the fundamental drive frequency for the machine and a superimposed signal component which is at a substantially higher frequency than the drive power. The rotor has saliencies which result in a change in impedance as seen at the stator windings to the high frequency excitation signal as a periodic function of rotor rotational position. Such saliencies are inherent in some permanent magnet synchronous and all synchronous reluctance machines, and may be provided by appropriate modification of the rotor of induction machines. The stator response at the signal frequency is then detected to provide a correlation between the response at the signal frequency and the rotor position. The detection of the response at the signal frequency is preferably carried out by a heterodyne detection process, by mixing signals at the signal frequency with the measured stator currents, and filtering the mixed signals to isolate the signal indicative of the rotor position. Conventional squirrel cage induction motors can be provided with sufficient spatial variations in the stator winding impedance as a function of rotor position in various ways, including varying the depth and/or width of the slots over the rotor conductive bars, by varying the cross-section of the bars, or by filling or partially filling some of the slots.

Method and apparatus for transducerless flux, position and velocity estimation in drives for ac machines

A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck The control circuit for the power tool is operable in a ratcheting or pulse mode that causes the output spindle to rotate in discrete incremental amounts Corresponding methods for controlling the operation of the electric motor of a power tool are also disclosed

Electrical power tool having a motor control circuit for providing control over the torque output of the power tool

A power conversion device includes a power switching circuit that supplies AC voltages generated between switching elements operating as upper arms and switching elements operating as lower arms, and a control circuit that generates and supplies to the driver circuit signals for controlling the switching operation of the switching elements by a PWM method in a first operational region in which frequency of an AC power to be outputted is low, and that generates and supplies to the driver circuit signals for controlling the switching operation of the switching elements at timings based upon the phase of the AC power to be outputted in an operational region in which the frequency of the AC power to be outputted is higher than in the first operational region.

Power Conversion Device

A method and system of obtaining a ten-print plain impression fingerprint includes scanning a print image, processing the scanned image, separating the processed image into individual fingerprint images, and determining how many print images have been scanned. The method also includes comparing the print image to a previously scanned print image, quality classifying the separated images, indicating a quality classification of the print image based on the classifying step, and determining whether the print image is of a good quality. The system can include a ten-print scanner having a finger guide and a platen used to position four finger slaps onto the platen.

Biometric imaging system and method

A control system for an electric motor having a stator and rotor including an inverter for providing power to the electric motor, a controller for controlling the inverter, a low speed control block to estimate the rotor angular position using stator current components operating in the controller, a high speed control block to estimate the rotor angular position using stator current components and stator flux position operating in the controller, a transition switch in the controller to vary operation between the low speed control block and the high speed control block, and where the inverter is controlled by six step operation.

Position sensorless control algorithm for ac machine

A method and apparatus for controlling torque by correcting slip gain error in an operating induction motor is provided. This is accomplished by measuring the amplitude and position of a flux in the motor such as rotor flux. Rotor flux position and amplitude can be estimated from the air gap flux. The slip gain can then be corrected in a single step or a few steps to provide a deadbeat control.

Motor torque control method and apparatus

Power is provided to the stator windings of an AC induction machine which includes a component at the fundamental drive frequency for the machine and a superimposed signal component which is at a substantially higher frequency than the drive power. The fundamental drive power is provided at a level which results in saturation in the stator which follows the magnetic flux vector. The stator response at the signal frequency is then detected to provide a correlation between the response at the signal frequency and the magnetic flux vector position. The detection of the response at the signal frequency is preferably carried out by a heterodyne detection process, by mixing signals at the signal frequency with the measured stator currents, and filtering the mixed signals to isolate the signal indicative of the flux vector position.

Method and apparatus for transducerless flux estimation in drives for induction machines

A sensor tip (10) for use in a robotic hand has a three-dimensional compliant elastomeric body (12) with an outer boundary (22) having a circular base (24) and a convex surface (26) extending therefrom. Four strain transducers (14, 16, 18, and 20) produce electrical signals indicative of the strain at various positions near the boundary of the elastomeric body (12) resulting from forces exerted upon the sensor tip (10) by an object which the robotic hand is manipulating. The transducers (14, 16, 18, and 20) are positioned about the convex surface (26) so as to produce signals that may be decoupled to determine the normal and tangential forces and the applied torque. A buffer amplifier circuit (34), one for each of the transducers (14, 16, 18, and 20), receives the signals and provides quasi-steady state force information. The circuit (34) connects the respective transducer (40) in a feedback loop around an amplifier (36) and has desirable attributes for static charge buffering. The sensor tip (10) is calibrated to determine proportionality constants for the decoupling algorithm for use of a force delivering system (60), which uses voice coils (74) to apply a force that is linearly related to the current introduced to each of the coils (74). A method of manufacture of the sensor tip (10) results in improved bonding between the transducers (14, 16, 18, and 20) and the elastomeric body (12) for better performance and longer life of the sensor tip (10).

/pdf/sensor-tip-for-a-robotic-gripper-and-method-of-manufacture-2oaw6xknwa.pdf

Sensor tip for a robotic gripper and method of manufacture

A piezoelectric positioner is accurately controlled to reduce the settling time of the positioner in response to a commanded change in position using velocity state feedback control The velocity state feedback control uses an estimated velocity of the piezoelectric positioner generated by a velocity observer to provide active damping The velocity observer has as inputs the same control signal which is provided to the piezoelectric positioner itself and the actual measured position of the positioner, and produces as an output the estimated velocity of the positioner The velocity observer includes a model of the piezoelectric positioner's response to the control signal The model includes estimates of physical parameters of the positioner including the physical mass, physical damping, and physical stiffness of the positioner Position and velocity state feedbacks are used within the observer model, in combination with the actual measured position of the positioner, to drive a modeled position of the positioner to equal the actual position, thereby also to increase the accuracy of the velocity estimate The observer state feedbacks reduce errors in the modeled position due to inaccuracies in the parameter estimations, noise, and unmodeled physical disturbances The positioner control with active damping may be implemented in any system using a piezoelectric positioner Active mass feedback, using an acceleration observer, may be added to the active damping feedback in piezoelectric systems in which the handling of force disturbances is required

Method and apparatus for improved control of piezoelectric positioners

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