370 results about "Active vibration control" patented technology

The invention discloses an active control device of vibration simulation for bending and torsional modes of space sailboards and a method. The device symmetrically sticks multi-chip bending mode piezoelectric actuators on front and rear faces of a flexible plate, a bending mode sensor is arranged at the position horizontally closing to a fixed end by 320-25mm of the flexible plate and on the longitudinal center line of the flexible plate, torsional mode actuators composed of a plurality of piezoelectric ceramic chips are antisymmetrically stuck on both faces of the flexible plate, and torsional mode sensors composed of a plurality of the piezoelectric ceramic chips are stuck on both faces of the flexible plate. The method operates an active vibration control strategy according to information of the bending mode and trosional mode sensed by a piezoelectric sensor, and then drives a voltage amplifier through piezo-electricity to respectively drive the piezoelectric actuators for controlling multimode vibrations of bending and torsion, thereby realizing the purpose of actively inhibiting the vibrations. The invention employs the optimum distribution of piezoelectric sensor chips and driving chips, and realizes decoupling of bending modes and torsional modes of flexible cantilever plates in inspection and drive control.

An active noise/vibration/sound control system for a vehicle has an ANC (active noise control apparatus), an AVC (active vibration control apparatus), and an ASC (active sound control apparatus). To prevent the ANC, the AVC, and the ASC from interfering with each other and hence to prevent vehicle cabin environment of vibrations, noise, and sound from being impaired, activation and inactivation of the ANC, the AVC, and the ASC are controlled or their control characteristics are controlled in relation to each other by a weighting variable calculator as a coordination controller, depending on an engine rotation frequency and a frequency change which are representative of a running state of the vehicle as detected by an engine rotation frequency detector and a frequency change detector that serve as a running state detector.

A magnetic levitation flywheel high-precision active vibration control system comprises a displacement sensor, a current sensor, a magnetic bearing controller and a PWM modulation and a power amplifier, wherein, the magnetic bearing controller comprises stabilization of the controller, eccentric estimation, magnetic force compensation and action of a switch. The magnetic levitation flywheel high-precision active vibration control system introduces the eccentric estimation and the magnetic force compensation on the basis of the stable control and utilizes the unbalance vibration parameters of a flywheel to carry out the compensation of the unbalance amount and the displacement negative stiffness of the flywheel within the entire rotation speed range, thus realizing the control of the unbalance vibration of the flywheel within the entire rotation speed range and allowing the flywheel to be operated around a principal axis of inertia with high precision during the whole process of speed increasing and speed reducing.

An apparatus for active vibration is provided for control of resonance vibrations in a computed tomography (CT) system. The apparatus comprises a sensor coupled to a support frame of the CT system for detecting resonance vibrations and and convert the vibration signal to a corresponding electrical signal. The apparatus further comprises a control device coupled to the sensor for implementing a control algorithm to process the electrical signal to generate a corresponding control signal, which is used for counteracting the resonance vibrations in the support frame.

In a motor-assisted hybrid vehicle, an active vibration control system suppresses torque fluctuations of an engine without detriment to the response of a static torque. An adaptive notch filter outputs a control signal depending on a harmonic basic signal generated by a basic signal generator from a rotational frequency of a crankshaft. A combiner combines the control signal with a drive signal for the generator motor and supplies the combined signal through a power controller to the generator motor. The basic signal is supplied to corrective filters having the transfer function of the generator motor to output a reference signal. The filter coefficient of an adaptive notch filter is successively updated so that an error signal representative of a rotational speed fluctuation of the crankshaft will be minimized.

A method includes the steps of: detecting “starter ON” by IG-SW signal (step S12); calculating an moving average value T_CRKAVE of crank pulse intervals (steps S13-S17); determining engine starting when the T_CRKAVE is less than or equal to a threshold value T_th (step S19); and controlling a vibration isolating support unit M based on a natural vibration frequency of the engine when engine starting is determined (steps S20-S22).

An active vibration control (AVC) system includes a shaft-driven gearbox mounted force generator (GMFG) mounted to a main rotor transmission. The GMFGs receive shaft power from an output shaft driven by the main rotor transmission and/or engine-to-transmission gearbox to avoid separate drive motors.

A vibration control system for a rotor hub provides vibration attenuation in an aircraft by reducing the magnitude of rotor induced vibratory. The system can include a force generating device attached to a rotor hub which rotates along with the rotor at the rotational speed of the rotor. Vibratory shear force is generated by rotating unbalanced weights each about an axis non-concentric with the rotor hub axis at high speed to create large centrifugal forces. The rotational speed of the weights can be a multiple of the rotor rotational speed to create shear forces for canceling rotor induced vibrations. The amplitude of the generated shear force is controlled by indexing the positions of the unbalanced weights relative to each other, while the phase of the shear force is adjusted by equally phasing each weight relative to the rotor.

An active vibration control system including a sensor responsive to a source of vibration and which provides an output signal representative of the vibrations; at least one actuator positioned to impart canceling vibrations to the source of vibrations based on an input signal; a correction subsystem responsive to the actuator for estimating the sensor output in the absence of the canceling vibrations and which outputs a corrected output signal representative only of the vibrations emanating from the source; and a state space predictor responsive to the corrected output signal for determining the input signal to the actuator based on variations in the corrected output signal to better control vibrations especially in chaotic systems.

The invention discloses a magneto-rheological damper with an asymmetrical controllable damping characteristic. The magneto-rheological damper comprises a magneto-rheological damper body, wherein a piston head of the magneto-rheological damper body is provided with a magnet exciting coil and separates an inner cavity of a cylinder barrel into a first accommodating cavity close to the lower end of the cylinder barrel and a second accommodating cavity close to the upper end of the cylinder barrel; convection holes which are communicated with the first accommodating cavity and the second accommodating cavity are formed inside the piston head; and valve components which are used for performing one-way throttling on a magneto-rheological fluid from the second accommodating cavity to the first accommodating cavity are arranged in the convection holes. The magneto-rheological damper with the asymmetrical controllable damping characteristic can enable recovery and controllable damping force to be larger than compression controllable damping force, can produce larger recovery damping force under smaller current, can prolong the recovery time, and is applicable to a vibration control system such as a motorcycle rear suspension or other vehicle suspension system, which requires asymmetrical controllable damping, and semi-active vibration control is realized by changing current of the magnet exciting coil of the magneto-rheological damper; and the magneto-rheological damper is simple in structure, can realize asymmetrical controllable damping force, and is low in use cost and beneficial to popularization and utilization.

The invention discloses an active vibration absorber with a flexible structure and a control method thereof. The active vibration absorber comprises a signal acquisition unit and a control vibration absorption unit; in the signal acquisition unit, the flexible structure is provided with an ICP acceleration transducer, and a signal is transmitted to a constant current source, a data acquisition device and an analog/digital converter in turn and then transmitted to a computer to be processed; and in the control vibration absorption unit, a computer control signal is transmitted to the analog/digital converter and a first power amplifier and then transmitted to an actuator to execute vibration absorption. In order to simulate external excitation, the active vibration absorber is provided with an exciting force output unit, a signal generator of the unit is connected with an input end of a second power amplifier, a signal generated by the signal generator is amplified by the second power amplifier and then input to a vibration exciter, and the vibration exciter is connected with the flexible structure through a post rod to provide external disturbance. The method mainly comprises an off-line recognition process and a real-time control process. A random walk and input estimation method is introduced into active vibration control of the flexible structure, and good control effect is acquired from an experimental angle.

The invention provides an active vibration damping system based on absolute displacement feedback and used for realizing active vibration damping on a load. The active vibration damping system comprises at least three vibration damping units used for realizing six degree-of-freedom active vibration damping on the load, wherein each vibration damping unit is provided with an absolute displacement measuring device, and the absolute displacement measuring device is used for detecting the absolute displacement of the load in real time; and a vibration damping control unit is respectively connected with the at least three vibration damping units, and the vibration damping control unit realizes active feedback control according to the absolute displacement. The vibration damping system based on the absolute displacement feedback has the following advantages: an air spring and a linear actuator work together to carry out active vibration damping, and the absolute displacement feedback technique is adopted to effectively improve the vibration damping performance of the vibration damping system, effectively increase position loop bandwidth of the vibration damping system and enhance the positional stability of the vibration damping system; and the active vibration damping system is convenient to use, small in size and lower in cost.

The invention discloses a large dynamic cubic Stewart active vibration control platform which comprises an upper platform body, a lower platform body, an actuator package, a sensor group and connecting pieces. The upper platform body and the lower platform body are each provided with three installation bases in the circumferential direction. Each installation base is provided with one connecting piece. The actuator package and the upper and lower platform bodies are installed through the connecting pieces. Actuator pairs are connected end to end. By means of the designed connecting pieces and the connection way between the actuator pairs and the connecting pieces, the position relation that the actuator pairs are installed with the same included angle is formed. The sensor group is installed on the upper surface of the upper platform body and used for detecting vibration accelerated speed signals of the upper platform body in six directions of degrees of freedom. The large dynamic cubic Stewart active vibration control platform has the advantages that the platform can work in the micro-amplitude low-frequency environment, the platform rotating space can range from -15 degrees to +15 degrees, the damping effect is about 98%, a vibration reduction control system is based on the platform, and the platform is convenient to operate and controllable.

The present invention relates to a method for regulating an active vibration isolation system and to an active vibration isolation system, in particular for a vibration isolated positioning of lithography-devices, wafer-handling-systems and/or microscopes, as for instance scanning microscopes. The active vibration isolation system comprises the following components: a support body for bearing a load which is to be isolated; pneumatic vibration isolators with controllable valves for carrying the support body with respect to the ground; position sensors for providing vertical position signals of the support body; a first regulating system for vibration compensation in at least one degree of freedom in translation (Xt,Yt,Zt) and in at least one degree of freedom in rotation (Xr,Yr,Zr) and a second pneumatic regulating system for vibration compensation in at least one degree of freedom selected from three degrees of freedom (Zt,Xr,Yr) which are effective in vertical direction.

The invention discloses a self-powered vibrational energy extraction circuit based on piezoelectric materials. The self-powered vibrational energy extraction circuit comprises an extreme value detection circuit module and a nonlinear energy extraction circuit module. The extreme value detection circuit module can detect an extreme value of quantity of electric charge in a piezoelectric element in real time, outputs drive signals of an analog switch at an extreme value position, controls a nonlinear energy extraction circuit to start or stop working, and converts surface charge of the piezoelectric materials to direct current to supply electricity to load. The functions of the whole circuit are all achieved through analog electronic parts and components. The self-powered vibrational energy extraction circuit can effectively improve energy density of an electro-mechanical transformation structure in a recovery unit, and at the same time ensures that the recovery unit has good performance within a wider vibration frequency band range. Therefore, the self-powered vibrational energy extraction circuit can be widely used in self-powered wireless sensor network nodes, self-powered semi-active vibration control systems, and other electronic modules which independently work with low power.

The invention discloses an electric spindle semi-active vibration control test stand, a system and an electric spindle control method, wherein the electric spindle semi-active vibration control method comprises the following steps: through a processor, an electric spindle torsional coupled vibration signal is separated by using an experience modal decomposition and Hilbert transformation method so as to obtain a test frequency and a test phase; through an electric spindle intensive parameter equivalent mechanical model and the design parameter of the electric spindle system, the theory frequency and theory phase of the bending vibration and the torsional vibration of the electric spindle are obtained; through a force synchronizing vibration control model, the testing frequencies of the bending vibration and the torsional vibration of the electric spindle are combined, the test phase, the theory frequency and the theory phase are combined, so that a first pulse-width modulation (PWM) signal of a magneto-rheological absorber used for controlling the bending vibration and a second PWM signal of the magneto-rheological absorber used for controlling the torsional vibration are generated respectively. Therefore the bending vibration and the torsional vibration of the electric spindle can be synchronously controlled.