Antagonistic Piezo Actuators for High-Bandwidth Camera Gaze Control
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Solution Overview
Problem
Conventional camera positioning systems using traditional servo-motors fail to replicate the natural eye's movement dynamics due to velocity saturations and backlash, limiting their bandwidth and ability to focus on rapidly changing areas of interest.
Innovation Solution
A camera positioning system employing antagonistic amplified piezoelectric ceramic stack actuators that pivot a substrate-mounted camera, mimicking the human eye's kinematics by using deformable actuators coupled through a transverse member to change the camera's angular orientation in response to a signal, allowing precise and efficient reorientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional servo-motors are used for camera positioning, then the system structure is simple and easy to manufacture, but velocity saturations and backlash occur which limit bandwidth and response speed
Solution Approach 1:
The patent replaces traditional servo-motors with amplified piezoelectric ceramic stack actuators. These actuators use piezoelectric effect to convert electrical signals directly into mechanical displacement, eliminating the need for traditional motor components that cause velocity saturation and backlash. The direct-drive mechanism achieves higher bandwidth and faster response while maintaining precise positioning control.
Solution Approach 2:
The patent changes the actuation mechanism from rotational motor output to linear piezoelectric displacement. By using amplified piezoelectric ceramic stacks with mechanical amplification mechanisms, the system transforms small piezoelectric displacements into larger camera positioning movements, achieving high-speed response without the limitations of traditional motor velocity characteristics.
2Measurement precision
If traditional servomotors are used, then manufacturing is easier, but backlash and velocity saturation reduce positioning precision
Solution Approach 1:
The patent eliminates traditional motor-gear-train mechanisms that inherently produce backlash by using direct-drive piezoelectric actuators. The amplified piezoelectric ceramic stacks directly position the camera through a simplified mechanical linkage, removing intermediate transmission components and achieving zero-backlash positioning with higher precision.
Solution Approach 2:
The patent introduces an amplification mechanism as an intermediary between the piezoelectric ceramic stack and the camera positioning system. This amplifier converts the small displacement of the piezoelectric actuator into larger camera movements, enabling precise positioning control without requiring complex high-precision mechanical components.
3Speed
If lightweight actuators are used to mimic eye muscles, then response speed increases, but actuator control complexity increases due to compliant behavior
Solution Approach 1:
The patent employs an antagonistic pair of actuators where one actuator contracts while the other extends, mimicking the balanced muscle-pair system in the human eye. This configuration provides inherent mechanical stability and equilibrium, allowing compliant actuators to achieve fast response speeds while maintaining controllable positioning through coordinated actuation of the actuator pair.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves precise and efficient reorientation of the camera, mimicking natural eye movement by overcoming velocity saturations and backlash, thereby improving the camera's ability to focus on changing areas of interest with increased bandwidth.
Implementation Method 1
A first actuator is affixed to a first side the frame and is disposed along a second axis that is transverse to the first axis. A second actuator is affixed to a second side of the frame and is disposed along the second axis. The first actuator and the second actuator are both deformable in response to a signal.
Data Source
AI summary
In a method of controlling a gaze direction of a camera, the camera is placed on a top surface of a substrate that is pivotally coupled to a frame, wherein a movement arm depends downwardly from the substrate. The movement arm is moved with two spaced apart amplified piezoelectric ceramic stack actuators that are affixed to the frame and coupled to the movement arm by deforming the amplified piezoelectric ceramic stack actuators as a result of applying a voltage thereto, thereby changing an angular orientation of the substrate.