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Team 1 Delta and Rasco Low Gravitational Gyro

Sponsor

Project Description

Micro Electro-Mechanical Systems (MEMS) have proliferated in recent years and are implemented in a wide range of applications, from determining the orientation of smartphones to deploying airbags. Calibrating MEMS can account for 10-40% of their production cost because each MEMS currently requires an onboard tester. The team designed a stimulator that externally tests multiple MEMS at once to eliminate this internal component, thus reducing the size and cost.

Project Objective

•  Module needs to accommodate up to 32 MEMS sensors

•  Static positioning of 0G, 1G, and -1G (see Figure below)

•  Static testing on all 3 axes in 2 seconds

•  Constant Rotational Velocity of 600 degrees per second (100 RPM) for 15 degrees of rotation

•  Dynamic testing on all 3 axes in 3 seconds

•  Operate in temperature range of - 60°C to 160°C

•  Position Accuracy of 0.2°

•  Velocity Accuracy of 2%

•  17.6” x 6.5”, 3kg MEMS platform

Final Design

Performances

• Can accommodate up to 32 MEMS

  • Platform dimension 17.6" x 6.5"

• Finishes testing on all 3 axes in approximately 8 sec

• Performs dynamic tests between static tests

• 0.14 °  positional accuracy

• Robust design

Remaining Concerns

• Temperature requirements

  • Not all components can withstand -60 to 160  °C

• Testing speed

  • Inside axis can only ramp up to 70 RPM 

• PID-controller stability

Recommendations

• Temperature Requirements

  • Insulation of delicate components

  • Cooling fins for controllers

• Improved Accuracy

  • Master-Slave controllers

  • Precise MEMS for homing sequence

• Testing Time

  • Lighter components

  • Ball bearing maintenance

• Cable Routing

  • Slip rings

  • Extended cables

  • Negotiable requirement

Executive Summary

    The production of Micro Electric-Mechanical Systems (MEMS) sensors has increased tremendously in recent years, causing companies to focus on reducing the manufacturing cost of MEMS. This can be achieved by implementing an external stimulator that performs the necessary tests on multiple chips simultaneously. Furthermore, with the stimulator, the overall size of MEMS will be reduced due to the elimination of the internal tester.

    The stimulator should be able to test up to 32 MEMS simultaneously. It also needs to perform both static and dynamic tests along all 3 axes in less than 2 and 3 seconds, respectively. For the dynamic tests, the speed requirement is 600°/s (100RPM) for duration of at least 15°. In addition, the accuracy of rotational position has to be less than 0.2°, and the accuracy of velocity has to be less than 2%. Along with the functional requirements of the stimulator, the design should be able to function in the temperature range of -60°C to 160°C. Also, to accommodate up to 32 devices and other electronics on-board, the dimension of the platform must be 17.6 x 6.5” and have a 3 kg mass.

    The final design of this stimulator was machined from Aluminum 6061-T6, which functions within the temperature requirement without deforming. Aluminum 6061-T6 not only met the temperature requirement but also was inexpensive and readily available. An analysis was run to determine the necessary motor torque in order to meet the functional requirements listed above. For the inside motor, 1.91 Nm was required and for the outside motor, 7.64 Nm was required.

    With the motors, controllers, and driver chosen, all the necessary simulation was complete, and the design was finalized. A two-axis gimbal was the final prototype design, and it will be able to perform all the required tests in less than 8 seconds.