A smart material actuator comprising a mechanical amplifier with a fixed supporting member, at least one mountable actuating arm, and mechanical web having at least one compliant member attached to the mountable arm and a movable supporting member. A piezoelectric stack is affixed between a first mounting surface on the fixed supporting member and a second mounting surface on the movable supporting member. With the fixed supporting member being substantially rigid, and the piezoelectric stack being affixed between the first mounting surface and the second mounting surface, which are substantially parallel, applying an appropriate electric potential to the piezoelectric stack will cause it to expand substantially without angular movement. The expansion urges the second mounting surface away from the first, thereby causing the compliant members of the mechanical web to flex, thereby moving the mountable actuating arm. The configuration of the web and the length of the mountable arm cause the actuating end of the arm to move across a distance greater than the expansion of the piezoelectric stack. In this way, the expansion of the stack is effectively amplified by the mechanical amplifier. Actuators of this type may be used both to create mechanical motion from electrical energy and to harvest electrical energy from mechanical motion, or sense the degree of such motion. A number of arm designs and means of attachment to external components are disclosed, in addition to methods of generating electricity from mechanical motion and generating vibration using such actuators and methods of tuning the resonant frequency and increasing the efficiency of energy harvesting through resonant operation.

Mountable arm smart material actuator and energy harvesting apparatus

A micro-scale, smart material actuator having an overall length smaller than 10mm comprising a multilayer piezoelectric stack housed in a mechanical amplifier made up of a fixed supporting member, a movable supporting member connected to compliant links attached to one or more actuating arms such that, when a suitable electric current is applied to the piezoelectric stack, the resulting expansion is translated through the movable supporting member, thereby causing movement in the actuating arms A method of generating electricity from motion using such an actuator is also disclosed in which the actuating arms are connected to a source of mechanical motion and the piezoelectric stack is connected to an electrical load, whereby the mechanical motion causes the piezoelectric stack to generate electrical charge that is then discharged into the load.

Small scale smart material actuator and energy harvesting apparatus

A method and a device for precisely resisting and moving a high load capable of accurately moving a mobile body in the vertical direction even when a pressing force is applied onto a large sliding surface by combining piezo elements causing shear deformation with a wedge or the piezo elements causing the shear deformation and piezo elements causing vertical deformation with the wedge. The piezo elements causing the shear deformation are stacked on each other so that their shearing directions are different from each other and combined with the wedge so that the mobile body can be accurately moved in the vertical direction even when the pressing force is applied to the large sliding surface. The device comprises a wedge-like moving element (23) disposed on the horizontal surface of a fixed body and to which the piezo elements (24A) causing the shear deformation are fixed, a pulse source (30) rapidly deformably driving the piezo elements (24A), and the mobile body (25) vertically moving in contact with the vertical wall surface (22) of the fixed body by the driving of the wedge-like moving element (23). The mobile body (25) can be moved and positioned by driving and extracting the wedge-like moving element (23) in and from the mobile body (25).

Method and device for precisely resisting and moving high load

A smart material actuator having a fixed supporting member, mechanical web, actuating arm, and piezoelectric or smart material stack is disclosed, together with a sensor adapted to indicate the degree of motion of the actuating arms and controller adapted to allow safe operation of the actuator in resonant conditions. Methods of maintaining resonant operation, avoiding resonant operation, and adjusting resonant frequencies are also disclosed.

Smart material actuator adapted for resonant operation

A smart material actuator including a smart material stack and a compensator preventing expansion of the stack in a non-driving direction. When actuated, the smart material stack causes a force transfer surface to be driven in the driving direction, thereby actuating a first stage amplifier having two arms, which in turn actuates a second stage amplifier having two arms.

Smart material actuator

An apparatus and process for pre-loading an electrically stimulated smart material actuator product to obtain maximum work from the actuator. When a smart material actuator is optimally pre-loaded certain desirable characteristics become apparent, such as work, operational frequency, hysteresis, repeatability, and overall accuracy. When used in conjunction with a mechanically leveraged actuator structure the smart material actuator can be used to its greatest potential. Since the mechanically leveraged actuator can be based on the maximum work provided by the smart material actuator, certain attributes such as the force, and displacement of total system can be adjusted without loss to system efficiency. Pre-loading methods and a determination of the optimal pre-load force are disclosed. Each smart material actuator type has a unique work curve. In the design of an actuator assembly, the process of optimizing uses the unique work curve to optimize the design for the requirements of the particular application. The unique work curve is used by finding the place where the smart material actuator is capable of providing the most work in order to set the optimum pre-load point accordingly. Different mechanical pre-load techniques are provided.

Keith A. Thornhill

Papers

Apparatus and process for optimizing work from a smart material actuator product