Resonant Acceleration Device for MEMS Testing
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Solution Overview
Problem
Existing methods for accelerating MEMS accelerometers require large forces, leading to energy inefficiency and reduced durability, and are often unable to achieve controlled, repeatable high acceleration levels, especially when used in environmental chambers.
Innovation Solution
A system utilizing an actuator with a voice coil motor and springs to apply a periodic force aligned with the mass's velocity, inducing resonance to achieve high acceleration levels efficiently, while minimizing the force required and allowing for environmentally controlled testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large force is applied to accelerate the DUT, nest, and tappet at high levels, then the acceleration level is improved, but the energy consumption increases and the motor durability deteriorates
Solution Approach 1:
The patent applies mechanical vibration by using a voice coil motor to generate oscillatory motion at resonant frequency. The periodic force excites the natural resonant frequency of the mass-spring system, producing high acceleration levels through resonance amplification rather than direct large-force application. This significantly reduces the energy required to achieve the same acceleration magnitude.
Solution Approach 2:
The patent changes the operational parameters by operating at resonant frequency rather than arbitrary frequencies. By tuning the voice coil motor to operate at the natural resonant frequency of the system, the acceleration is amplified for a given input force, thereby reducing energy consumption while maintaining high acceleration levels.
2Speed
If a large force is applied to accelerate the DUT, nest, and tappet at high levels, then the acceleration level is improved, but the motor durability deteriorates
Solution Approach 1:
By utilizing resonant vibration, the system achieves high acceleration through oscillatory motion rather than continuous large-force application. This reduces stress on the voice coil motor, minimizing wear and extending motor life while maintaining the capability to generate high acceleration levels during testing.
Solution Approach 2:
The patent employs periodic action by applying force in oscillatory cycles at resonant frequency. The voice coil motor alternates between pushing and pulling the mass, creating high acceleration during each cycle without requiring sustained large forces. This periodic operation reduces cumulative stress on the motor components.
3Speed
If conventional acceleration methods are used, then high acceleration levels can be achieved, but the acceleration profile is erratic and not sufficiently repeatable
Solution Approach 1:
The resonant vibration approach produces a consistent, predictable acceleration profile because resonance occurs at a specific natural frequency of the system. By controlling the voice coil motor to operate at this resonant frequency, the system generates repeatable acceleration magnitudes and waveforms, eliminating the erratic behavior associated with impact-based methods.
Solution Approach 2:
The patent incorporates feedback by using the accelerometer under test to measure the actual acceleration and feed this information back to the control system. This closed-loop control allows real-time adjustment of the voice coil motor to maintain resonant operation and consistent acceleration profiles across multiple test cycles, ensuring high repeatability.
4Speed
If a rotating drum is used to obtain centrifugal forces, then high acceleration can be achieved, but the system requires large torque and becomes cumbersome
Solution Approach 1:
The patent replaces the rotating drum centrifugal force method with resonant vibration. Instead of requiring large torque to rotate a heavy drum at high speeds, the voice coil motor uses periodic electromagnetic force to excite resonant oscillation of a lighter mass. This dramatically reduces the power and torque requirements while achieving comparable or superior acceleration levels.
Solution Approach 2:
The patent substitutes the mechanical rotating drum system with an electromagnetic voice coil motor system. The voice coil motor uses electromagnetic fields to generate force, replacing the mechanical torque transmission through gears and bearings required by the rotating drum. This substitution reduces mechanical complexity and power requirements.
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 high acceleration levels with significantly reduced force requirements, enhancing energy efficiency and durability, and allows for controlled, repeatable testing of MEMS accelerometers, even in environmental chambers.
Implementation Method 1
The actuator may include a voice coil motor, where the voice coil motor includes a permanent magnet and an armature and where the armature includes part of the mass
Implementation Method 2
The actuator is used to apply a force to achieve resonance
Implementation Method 3
at least one spring connecting the mount to the mass
Implementation Method 4
The actuator is used to apply a force to achieve resonance
Data Source
AI summary
An acceleration device includes an actuator configured to displace a mass in a reciprocating motion at a desired frequency, a mount configured to hold a device, such as an accelerometer device, and at least one spring connecting the mount to the mass. The actuator is used to apply a force to achieve resonance. The actuator may comprise a voice coil motor, wherein the voice coil motor includes a permanent magnet and an armature and wherein said armature comprises part of said mass. The actuator applies a periodic force to the mass. The periodic force may be a sinusoidal force. Preferably, the applied force is aligned with a resulting velocity of the mass. The mount may include a test socket to which the device is electrically connected. The spring may comprises one or more flexure elements. The acceleration device may be used with a handler device to connect and disconnect the device to and from the mount. Optionally, the handler device includes an environmental chamber surrounding the mount.