Hexapod Shaker with 1000 Hz Bandwidth for Gyro Vibration Testing
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Solution Overview
Problem
State-of-the-art gyroscopes, particularly fiber optic gyros for space applications, are susceptible to low-level vibrations that cause abrupt shifts in bias, which are not effectively identified using standard test techniques and are nonlinear, requiring realistic six degrees of freedom (6DOF) mechanical excitation to simulate spacecraft environments.
Innovation Solution
A hexapod shaker system with six individually controllable strut assemblies, utilizing high-precision linear electromagnetic actuators and non-contact sensors, enabled by a closed-loop, programmable controller with a control bandwidth of 1000 Hz or more, to precisely control the top plate's motion in all directions and axes, replicating realistic spacecraft motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard gyro test techniques are used, then testing is simple and quick, but low-level vibrations causing bias shifts are not identified
Solution Approach 1:
The test system is segmented into six independent strut assemblies, each capable of individual control along specific axes. This segmentation allows precise application of vibrations along different degrees of freedom, enabling detection of low-level vibrations that affect gyro performance while maintaining manageable control through modular architecture
Solution Approach 2:
The hexapod shaker system implements dynamic control with bandwidth exceeding 1000 Hz, allowing real-time adjustment of vibration characteristics across six degrees of freedom. This dynamic capability enables the system to identify and characterize low-level vibrations that cause bias shifts in gyroscopes, transforming the test approach from static to highly dynamic and adaptive
2Manufacturing precision
If high control bandwidth is implemented, then motion control precision at high frequencies is improved, but system complexity and cost increase
Solution Approach 1:
The system implements closed-loop feedback control with bandwidth exceeding 1000 Hz, using sensors to continuously monitor the position and motion of the top plate. This feedback mechanism enables precise control of vibrations at high frequencies, achieving motion control precision of 20 nm or less while managing system complexity through intelligent control algorithms
Solution Approach 2:
The patent replaces traditional mechanical linkage systems with electromagnetic actuators (voice coil actuators) that provide direct, precise control of strut assemblies. This substitution eliminates complex mechanical transmission components, reduces inertia, and enables high-frequency response with bandwidth exceeding 1000 Hz, achieving precise motion control without excessive mechanical complexity
3Adaptability or versatility
If hexapod structure with six strut assemblies is used, then 6DOF motion control is achieved, but device complexity increases
Solution Approach 1:
Each of the six strut assemblies is designed as a universal, independently controllable unit capable of generating motion along its specific axis. This universality allows the system to achieve all six degrees of freedom (three translational and three rotational) through coordinated operation of identical modular components, enhancing adaptability while managing complexity through standardization
Solution Approach 2:
The hexapod system segments the 6DOF motion control into six independent strut assemblies, each responsible for a specific degree of freedom. This segmentation allows precise control of vibrations along different axes, enabling comprehensive testing of gyroscopes under realistic spacecraft motion conditions while maintaining modular architecture for manageable complexity
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 allows for precise testing of gyros and other devices under realistic 6DOF motions, effectively identifying and mitigating the effects of low-level vibrations, ensuring stable performance by simulating high-frequency spacecraft environments with sub-nanometer resolution.
Implementation Method 1
Each strut assembly comprises: an electromagnetic actuator for extending and contracting the strut assembly along a linear stroke length based on a control signal from the programmable control circuit
Implementation Method 2
a non-contact position sensor for sensing a stroke position of the strut assembly along the linear stroke length
Implementation Method 3
the strut assemblies may comprise, at each end thereof, stiff, bendable flexures to attain the repeatable and linear motion required
Data Source
AI summary
A shaker for enabling the testing of gyros and/or other devices for performance under realistic 6DOF motions. The shaker may be implemented as a hexapod, comprising a plate and six individually, simultaneously, and real-time controllable strut assemblies that are capable of extending and contracting linearly. The strut assemblies may comprise high-precision, linear electromagnetic actuators. The strut assemblies may also comprise high-precision non-contact sensors to sense the extension/contraction of the strut assemblies along their stroke length. In addition, the strut assemblies may comprise, at each end thereof, stiff, bendable flexures to attain the repeatable and linear motion required. The controller preferably has a control bandwidth of 1000 Hz or more, so that the motion of the plate can be precisely controlled to realize realistic 6DOF motions.