Showing papers on "Active vibration control published in 1982"

Active vibration isolator

Abstract: An active vibration isolator for removing vibration between a vibration source and a payload. The payload being various types of equipment such as measuring instruments, a camera, a vehicle seat, weaponry and other types of devices whose performance is sensitive to vibration. The isolator suspending the payload from a coil spring attached to the vibration source. A solenoid is mounted between the spring and the payload and an electrical control system is used to control the solenoid so the solenoid moves in an equal but opposite direction to the vibration on the spring thereby stablizing the payload.

Suppression of vibration effects on piezoelectric crystal resonators

Abstract: An active method and apparatus for suppressing or cancelling the effects of vibration on quartz crystal controlled oscillators by generating an electrical signal which is a replica of the vibration acting on the crystal resonator, which signal is thereafter properly phased and applied directly to the crystal electrodes which thereby operates to substantially eliminate unwanted vibration-induced sidebands in the signal output of the oscillator.

Device for restraining vibration of structural body

Abstract: PURPOSE:To effectively and accurately restrain the vibrative disturbance from a ground regardless of the changes in the vibration characteristics with the lapse of time, by utilizing the inertial force of an attached weight to actively damp the vibration through a servomechanism which responds to only a component of the vibration of a structural body. CONSTITUTION:A vibration sensor 7 detects the sum of the horizontal accelerations of a structural body 1 and a ground 2. Another vibration sensor 8 detects only the horizontal acceleration of the ground 2. Only the horizontal acceleration of the structural body 1 is obtained by a subtraction circuit 9 and applied to a control circuit 6, which supplies a dynamoelectric actuator 4 with an electrical current corresponding to the vibration of the structural body 1. The actuator 4 drives an attached weight 3. At that time, a driving force is caused as a reaction to the static part of the actuator 4 so that a force opposing the vibration is applied to the ceiling 1a of the body 1 through a securing member 5 to damp and restrain the vibration of the body. Such a closed-loop servomechanism is not affected by the time-lapse changes of the vibration system.

Vibration limiting of rotors by feedback control

Abstract: Experimental findings of a three mass rotor with four channels of feedback control are reported. The channels are independently controllable with force being proportional to the velocity and/or instantaneous displacement from equilibrium of the shaft at the noncontacting probe locations (arranged in the vertical and horizontal attitudes near the support bearings). The findings suggest that automatic feedback control of rotors is feasible for limiting certain vibration levels. Control of one end of a rotor does afford some predictable vibration limiting of the rotor at the other end.

Drive system for vibration wave motor

Abstract: PURPOSE:To improve the rising characteristics at the starting time by generating a standing vibration wave by electromechanical energy converting means before starting and storing the vibration energy in a stationary unit. CONSTITUTION:When a power source switch 9 becomes ON, only an electrostrictive element 3b operates, and only a standing vibration wave 13 is generated. In this state, only lateral vibration, i.e., elevational motion occurs on the mass point except the node on the frictional contact surface of a stationary unit 2. Thus, the vibration energy is stored in the unit 2, and starting is prepared. When a start switch 7 is then closed, a standing vibration wave 12 is generated by an electrostrictive element 3a, combined with the wave 13, thereby generating a travelling vibration wave 14. Since the vibration energy is stored before starting, the rise of the wave 14 becomes fast.

Early Detection of Excessive Coil Vibration in High-Voltage Rotating Electric Machines

Abstract: A safe and effective method of measuring stator end-winding vibrations of rotating electrical machinery and a vibration monitor are described. The method adopted is to measure electromagnetic vibration of the end-winding generating high voltage during operation. Measurements are obtained by piezoelectric pickups attached to end-winding surfaces. This method is often applied to measure vibration at other points, but it is difficult to effectively and safely measure end-winding vibration in the presence of high voltage and large current.

Device for measuring the icing on machines having natural vibration

Abstract: The invention relates to an arrangement for measuring the degree of icing on elements or other components of machines which have natural vibration. A diaphragm (3) clamped on a rigid support (1) is set in vibration itself by the natural vibration of the machine. By any icing (7) which appears, the diaphragm is damped and the vibration amplitude is reduced. The deflection is converted into electric signals by a bending sensor (4), which are displayed.

Optimum damping locations for structural vibration control

Abstract: A technique for determining the optimum damper locations and damping rates for a flexible structure has been developed. Using a nonlinear-mathematical-programming algorithm, a diagonal damping matrix is determined such that specified modes have a prescribed modal damping ratio. The design objective is to minimize the total damping effort while constraining the modal damping ratio to be equal or greater than the prescribed amount. Additional constraints require the diagonal elements of the damping matrix to be positive which guarantees that all modes of the damped system will be stable. Results are shown for a uniform free-free beam.