Ultrasonic positioner with multiple degrees of freedom of movement
First Claim
1. An ultrasonic positioning system having multiple degrees of freedom of movement comprising:
- (a) a plurality of piezoelectric ceramic elements, each capable of an elastic deformation response when an electrical signal is applied thereto, bonded in electrical contact with respective electrodes;
(b) an elastic body bonded in physical contact with deformable surfaces of the ceramic elements;
(c) a moving body movably supported in physical contact on the elastic body;
(d) wherein the ceramic elements are grouped in pairs of adjacent ceramic elements of opposite deformation responses aligned in a first direction, and also pairs of adjacent ceramic elements of opposite deformation responses aligned in a second direction; and
(e) means, including respective electrodes bonded to the ceramic elements, for applying an alternating electrical signal to produce a cyclic deformation response in the ceramic element pairs aligned in the first direction to produce a traveling wave for moving the moving body in the first direction, and for applying another alternating electrical signal to produce a cyclic deformation response in the ceramic element pairs aligned in the second direction to produce a traveling wave for moving the moving body in the second direction, whereby at least two degrees of freedom of movement in the first and second directions are obtained;
wherein an array of rectangular ceramic elements, each having a length different from its width, are grouped in pairs of ceramic elements of opposite deformation responses aligned with their lengths in an X direction and their widths in a Y direction, said array of ceramic elements being arranged for vibrating in two modes such that when an excitation signal of a first frequency corresponding to the length of the ceramic elements is applied, the ceramic element pairs aligned in the X direction produce a cyclic deformation response in the X direction, and when an excitation signal of a second frequency corresponding to the width of the ceramic elements is applied, the ceramic element pairs aligned in the Y direction produce a cyclic deformation response in the Y direction.
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Abstract
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.
31 Citations
10 Claims
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1. An ultrasonic positioning system having multiple degrees of freedom of movement comprising:
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(a) a plurality of piezoelectric ceramic elements, each capable of an elastic deformation response when an electrical signal is applied thereto, bonded in electrical contact with respective electrodes; (b) an elastic body bonded in physical contact with deformable surfaces of the ceramic elements; (c) a moving body movably supported in physical contact on the elastic body; (d) wherein the ceramic elements are grouped in pairs of adjacent ceramic elements of opposite deformation responses aligned in a first direction, and also pairs of adjacent ceramic elements of opposite deformation responses aligned in a second direction; and (e) means, including respective electrodes bonded to the ceramic elements, for applying an alternating electrical signal to produce a cyclic deformation response in the ceramic element pairs aligned in the first direction to produce a traveling wave for moving the moving body in the first direction, and for applying another alternating electrical signal to produce a cyclic deformation response in the ceramic element pairs aligned in the second direction to produce a traveling wave for moving the moving body in the second direction, whereby at least two degrees of freedom of movement in the first and second directions are obtained; wherein an array of rectangular ceramic elements, each having a length different from its width, are grouped in pairs of ceramic elements of opposite deformation responses aligned with their lengths in an X direction and their widths in a Y direction, said array of ceramic elements being arranged for vibrating in two modes such that when an excitation signal of a first frequency corresponding to the length of the ceramic elements is applied, the ceramic element pairs aligned in the X direction produce a cyclic deformation response in the X direction, and when an excitation signal of a second frequency corresponding to the width of the ceramic elements is applied, the ceramic element pairs aligned in the Y direction produce a cyclic deformation response in the Y direction. - View Dependent Claims (2, 3, 8, 9, 10)
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4. An ultrasonic positioning system having multiple degrees of freedom of movement comprising:
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(a) a plurality of piezoelectric ceramic elements, each capable of an elastic deformation response when an electrical signal is applied thereto, bonded in electrical contact with respective electrodes; (b) an elastic body bonded in physical contact with deformable surfaces of the ceramic elements; (c) a moving body movably supported in physical contact on the elastic body; (d) wherein the ceramic elements are grouped in pairs of adjacent ceramic elements of opposite deformation responses aligned in a first direction, and also pairs of adjacent ceramic elements of opposite deformation responses aligned in a second direction; and (e) means, including respective electrodes bonded to the ceramic elements, for applying an alternating electrical signal to produce a cyclic deformation response in the ceramic element pairs aligned in the first direction to produce a traveling wave for moving the moving body in the first direction, and for applying another alternating electrical signal to produce a cyclic deformation response in the ceramic element pairs aligned in the second direction to produce a traveling wave for moving the moving body in the second direction, whereby at least two degrees of freedom of movement in the first and second directions are obtained; wherein the electrodes, ceramic elements, and elastic body are arranged in four linear beams, with two beams aligned in parallel in the X direction and two beams in parallel in the Y direction, and a movable rotor is supported as the moving body in preloaded contact on the beams, and when excitation signals are applied to each two parallel beams to generate travelling waves in the same X or Y direction, linear movement of the rotor in the X or Y direction results, and when excitation signals are applied to each two parallel beams to generate travelling waves in the opposite X or Y direction, rotary motion of the rotor results, whereby three degrees of freedom of movement are obtained. - View Dependent Claims (5, 6, 7)
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Specification