Mechanical Eyeball Actuation Using Differential Gear Train
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Solution Overview
Problem
Existing animatronic devices with mechanical eyeballs face challenges in accurately tracking and mimicking human eye movements due to the complexity and space inefficiency of push rod systems, which introduce significant error and variability in calibration.
Innovation Solution
The design of mechanical eyeballs that rotate about two intersecting axes, decoupled to allow independent movement, utilizing a differential gear train and encoder bars to precisely control the rotation, mirroring human eye movements with a controller-driven system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If push rod systems are used to control mechanical eyeball rotation, then the eyeball can be oriented in desired directions, but the system consumes significant space and introduces measurement error
Solution Approach 1:
The patent replaces the complex push rod mechanical system with a spherical coordinate system approach. Instead of using multiple push rods to control rotation, the invention uses a single push rod that applies force along a radial direction from the center of the eyeball. The position is controlled by adjusting the angle and length of this single push rod, eliminating the need for multiple interconnected mechanical components and reducing measurement errors from mechanical linkages.
Solution Approach 2:
The patent changes the control parameters from multiple push rod angles and lengths to a single push rod with variable angle and length. By expressing the eyeball orientation in terms of spherical coordinates (azimuthal angle and polar angle), the system transforms a multi-parameter mechanical control problem into a simpler two-parameter control problem, reducing device complexity while maintaining precision.
2Adaptability or versatility
If push rod systems are used to control mechanical eyeball rotation, then rotation in multiple directions is achieved, but the system occupies excessive space
Solution Approach 1:
The patent replaces the bulky multi-rod mechanical system with a compact spherical coordinate implementation. A single push rod with adjustable angle and length replaces multiple fixed-length push rods, dramatically reducing the volume required for the mechanical system while maintaining full rotational capability in multiple directions.
Solution Approach 2:
The single push rod in the invention serves multiple functions that would require separate components in traditional systems. By varying the angle and length of this single push rod, the system can achieve rotation about multiple axes and reach various positions in three-dimensional space, making the push rod a universal actuator for all rotation needs.
3Measurement precision
If traditional push rod systems are used, then eyeball positioning is achieved, but calibration variability increases due to arm angle changes
Solution Approach 1:
The patent changes from fixed arm length push rods to variable length push rods. By allowing the push rod length to change independently of the angle, the system can maintain consistent calibration across different positions. The controller can compensate for arm angle changes by adjusting the push rod length, ensuring that the relationship between control signals and eyeball position remains predictable and consistent throughout the range of motion.
Data Source
AI summary
An animatronic device includes a mechanical eyeball configured to rotate about a first rotational axis and a second rotational axis that intersect at a fixed center point. A controller is configured to generate eye movement instructions that cause the animatronic device to rotate the mechanical eyeball about at least one of the first rotational axis and the second rotational axis. The eye movement instructions are generated based on an eye tracking system used to track movement of an eye of a user. The controller maps the tracked eye movement to movement of the mechanical eyeball and generates eye movement instructions based on the mapping.