| 摘要 |
An ultrasonic positioning system having multiple degrees of freedom of movement includes an array of piezoelectric ceramic elements grouped in pairs of adjacent ceramic elements of opposite deformation responses aligned in a first direction and also pairs aligned in a second direction, an elastic body bonded to the ceramic elements, and a moving body movably supported on the elastic body for movement in at least the two directions. The pairs of ceramic elements are activated with offset pairs of ceramic elements by electrical signals offset in phase to generate a traveling wave for driving the moving body. In a preferred embodiment, the ceramic elements have a length to width ratio of 2:1 with their lengths aligned in the X direction and widths aligned in the Y direction. When excitation signals having a frequency corresponding to either their length or width are applied, the ceramic elements can vibrate in two modes to drive the moving body in the X or Y direction. Another embodiment provides three degrees of freedom by arranging the ceramic elements in four linear beams in parallel sets of two beams each for driving a rotor in the X direction and in the Y direction, respectively, and in rotary motion when opposite traveling waves are generated in each set of parallel beams. The ceramic elements may also be arranged on a spherical surface to drive a body in pitch and yaw motions, or by combining an upper hemispherical assembly for pitch and yaw motions and a lower hemispherical assembly for roll motion to provide three degrees of freedom of movement.
|
