The disclosure relates to a drive means for non-resonant linear and/or rotary positioning of an object, comprising at least two piezoelectric or electrostrictive actuator groups, where-in a first actuator group moves a first runner portion relative to a stationary base of the drive means according to the principle of an inertia drive, and by means of the second actuator group a second runner portion is moved relative to the first runner portion with a limited range of movement in the high-resolution scan mode, wherein a common electrical control signal is applied to the first and second actuator groups.

The invention relates to a method and an actuator system for determining and applying a voltage to a piezoelectric actuator (PEA) to achieve a given setpoint displacement. The method involves determining a relation d.sub.cal(V) between a PEA displacement measure (d) and voltage (V) and a relation tt.sub.cal(V) between transition time (tt) and voltage and combining the determined relations to calculate a relation d(tt) between the displacement measure and transition time during an initial calibration procedure. This relation is characteristic for the PEA, and by determining a new relation tt.sub.new(V) after repeated biasing of the PEA, a compensated relation d.sub.c(V) can be calculated by substituting tt.sub.new(V) in the calculated d(tt). The compensated relation d.sub.c(V) compensates for piezo creep effects due to the wear and can be used to determine the voltage to be applied directly, or be used in other compensation algorithms.

A virtual resistive load feedback circuit for driving a piezoelectric actuator is provided that accounts for a hysteresis error and drift within the movement of the actuator. The circuit may include a voltage divider and charge divider. A voltage monitor signal corresponding to a voltage of a driver signal and a current monitor signal corresponding to a current provided to the amplifier are combined by an operational amplifier and include electrical characteristics of the actuator such that the circuit approximates a virtual load across the actuator. A feedback portion of the operational amplifier may include a resistor and capacitor connected in parallel to provide the voltage and charge divide functions. The use of the virtual resistive circuit allows for the piezoelectric actuator to be ground referenced, with no external components connected directly to the actuator while gaining the feedback effect to counter the hysteresis and drifts errors of the actuator.

A linear actuator has a base, a linear guide coupled to a flat, planar side of the base and extending in a travel length of an object to be moved, a contact plate extending along the flat, planar side of the base, and a carriage. The carriage includes an enclosure formed of an acoustically isolating material, a moving element configured to move along the guide and is coupled to the enclosure, a piezoelectric element including a contact site in physical contact with the contact plate, and a housing elastically holding the piezoelectric element, the housing coupled to the enclosure with no direct contact with the moving element. An electrical power source is in electrical communication with the piezoelectric element, wherein the power source energizes the piezoelectric element to effectuate movement of the carriage along the linear guide via the physical contact between the contact site and the contact plate.

A method of controlling a piezoelectric motor as a piezoelectric drive device having a vibrator including piezoelectric elements, a rotor as a driven unit that moves at a target speed by vibration of the vibrator, and drive signal generation units that generate drive signals and output the drive signals to the piezoelectric elements, includes intermittently outputting the drive signals to the piezoelectric elements by the drive signal generation units, wherein a time when output of the drive signals is stopped is shorter than a time from when output of the drive signal is stopped to stoppage of the vibration.

A simple rugged motor has a stator and a rotor formed by stacked silicon steel sheets operates by having a plurality of major and minor coil windings of the stator individually electrified under signals of a control unit, so as to steadily drive a rotor thereof. The simple rugged motor further has an orbit coupling balance assembly engaging an orbiting scroll for a corresponding fixed scroll disposed in a compression chamber to orbit for air compression, so as to form a scroll compressor. Or the simple rugged motor has a coupling assembly engaging a female screw compressor rotor to compress the air by a rotatable male screw compressor rotor disposed in a compression chamber, so as to form a screw compressor.

A method is disclosed for closed-loop motion control of an ultrasonic motor having at least one actuator with an excitation electrode and at least one common electrode, an element to be driven, a controller and at least one electrical generator for generating at least first and second excitation voltages U1 and U2 to be applied to the electrodes of the actuator for vibration of the actuator. A friction element of the actuator, due to its vibration, intermittently contacts the element to be driven with a driving force. The method includes providing the at least two excitation voltages U1 and U2 with different resemblance frequencies, a frequency difference deviating from a servo sampling frequency of the controller by 5 kHz at the most, and simultaneously applying the excitation voltages to the electrodes of the actuator.

A method of controlling a piezoelectric driving apparatus including a vibration section that has a piezoelectric element and a transmission section that transmits vibration of the vibration section to a driven body, and, by energization of the piezoelectric element, vibrates the vibration section in a combination of longitudinal vibration and bending vibration to cause the transmission section to perform an elliptical motion and to move the driven body by the elliptical motion, the method of controlling the piezoelectric driving apparatus including switching, according to an external force received by the driven body, a drive algorithm of the piezoelectric driving apparatus between a first drive mode in which a separation amplitude, which is an amplitude of the longitudinal vibration, is changed while a feed amplitude, which is an amplitude of the bending vibration, is constant and a second drive mode in which both the feed amplitude and the separation amplitude are changed.

A charge controller for controlling a piezoelectric actuator includes a decoupled high-frequency path for controlling the actuator in response to relatively high frequency input signal and a decoupled low frequency path for controlling the actuator in response to a relatively low frequency input signal. The charge controller includes a self-compensating circuit. Features of the charge controller allow for linear control of the piezoelectric actuator without utilizing feedback sensors or complex models.

An ultrasonic motor includes an annular vibrator and an annular moving member that is brought into pressure-contact with the vibrator. The vibrator includes an annular vibrating plate and an annular piezoelectric element. The piezoelectric element includes an annular lead-free piezoelectric ceramic piece, a common electrode arranged on one surface of the piezoelectric ceramic piece, and a plurality of electrodes arranged on the other surface of the piezoelectric ceramic piece. The plurality of electrodes include two drive phase electrodes, one or more non-drive phase electrodes, and one or more detection phase electrodes. A second surface of the vibrating plate includes a plurality of groove regions extending radially, and the depths of the groove regions change in a circumferential direction along a curve obtained by superimposing one or more sine waves on one another. The ultrasonic motor exhibits a sufficient drive speed while suppressing generation of an unnecessary vibration wave.