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ITT Mirror Steering System Team P11565

ITT Mirror Steering System Team P11565. Andrew Bishop Katie Hall Matt Manelis Ben Geiger Nurkanat Suttibayev. Agenda. Project Goals.

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ITT Mirror Steering System Team P11565

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  1. ITT Mirror Steering System Team P11565 Andrew Bishop Katie Hall Matt Manelis Ben Geiger NurkanatSuttibayev

  2. Agenda

  3. Project Goals The mission of this project is to design and build a mirror steering system that can outperform commercially available systems in terms of Power Consumption. This project will provide appropriate documentation that can be utilized by future senior design teams for further refinement.

  4. Project Description The mirror steering system is a device that controls the angle of a mirror in two dimensions. This device is used in directing optical devices at the mirror and aiming the mirror at an object located a far distance away. The tilting of the mirror is achieved by the use of actuators, which push and pull the mirror into different locations.

  5. Project Appeal High Interaction between Mechanical and Electrical Designs which creates more design challenges The goal is to compete with and do better than commercially available designs The chance to work hands on with a design outside of our previous experiences.

  6. Customer Needs Importance Ranking: 9 – These needs have the highest importance and will be the main focus of the project 3 – These needs are somewhat important and will be the secondary focus of the project if time allows 1 – These needs are not as important as the rest of the needs and will only be focused on if the main and secondary needs have been satisfied

  7. Target Specs Importance Ranking: 9 – These needs have the highest importance and will be the main focus of the project 3 – These needs are somewhat important and will be the secondary focus of the project if time allows 1 – These needs are not as important as the rest of the needs and will only be focused on if the main and secondary needs have been satisfied

  8. System Design • 2 Voice coils and 1 sensor Per Axis • Flexure Spring Mounting • PID Controller with VCCS Stage • Underhung Voice Coil

  9. System Design (Section View)

  10. Mechanical System Model Jӫ ө c1 c2 k k y X(t) F1 x F1 L2 L2 L1 L1 Model for Axis 1 (ө-direction)

  11. Complete System Model • PID controller to ensure system stability and settling time. • The Trans-conductance (voltage converted to current) stage can be modeled as an attenuation. • The voice coil is also modeled as a gain stage. • PID controller is being tuned

  12. Voice Coil • The basics of the voice coil is a device that uses current flow through a loop of wire and opposes a magnetic field to produce a force in single direction (positive or negative). • It is the heart of the system and everything was based off of the force and dimensions of the Vc for a given input current.

  13. Voice Coil Continued The final design included 2 different voice coils, both with a 20mm outer diameter, one being 32mm tall, the other being about 22mm tall The 22mm tall VC has a higher magnetic field of .33T field in the gap area, the taller one having .38T field. Height not being too much of an issue for these gave us the choice to use the stronger field, and so giving more force for a given current.

  14. Mechanical Design Main assembly:- Waffle mirror (provided by ITT) attached to mirror mount by RTV adhesive- Flexure spring that allows system range of motion- Stem that connects the flexure to the top face of electronics box- Four actuators connected to mirror mount that will push and pull on mirror mount with generated force

  15. Relating Design to Needs/Specs Mirror Mount- CN8 (Size): The surface area of the mount is large enough to fit the flexure, voice coil contact point, and sensors, while not exceeding the diameter of the mirror- CN13 (Feasibility): The thickness is a standard value that can easily be purchased in stock (0.16’’)- ES3 (Modulus of Elasticity): Material must be stiff enough to withstand the forces and stresses imposed on part (6061 Aluminum)

  16. Finite Element Analysis To determine the displacement and stresses of the model, Finite Element Analysis is required SolidWorks/COSMOS software used for FEA Two types of analyses performed- Mirror and Flexure Structure- Electronics Box

  17. Mirror and Flexure FEA Setup To perform this analysis, the model is first constrained on the bottom face To simulate actuators acting in one axis, an upward force of 0.105 lbf is applied at one actuator, and a downward force of 0.105 lbf is applied at the other actuator To simulate actuators in two axes, two additional forces are added to the model at the other actuators

  18. Mirror and Flexure FEA Results • One axis simulation- Displacement: 0.0587 in- Angle: 2.24º- Max Stress: 8350 psi- FOS: 4.78 von Mises Stress Displacement Factor of Safety

  19. Mirror and Flexure FEA Results • Two axes simulation- Displacement: 0.0825 in- Angle: 3.15º- Max Stress: 10296 psi- FOS: 3.87 von Mises Stress Displacement Factor of Safety

  20. Electrical Box FEA Setup To perform this analysis, the model is first constrained on the bottom face The total weight of the components is summed, and applied on the top surface of the box Extra weight is added to simulate a worst case scenario (total force = 5lbs)

  21. Electrical Box FEA Results • Results:- Displacement: 1.37e-5 in- Max Stress: 64.4 psi- FOS: 619 von Mises Stress Displacement Factor of Safety

  22. Determining Spring Constant To determine the spring constant of the flexure, varying forces were applied to the mount, and displacement was measured for each data set A graph was generated to show the Force and Displacement relationship The slope of the line is equal to the spring constant Simulated spring constant equal to 626.8 N/m, or 3.58 lbf/in

  23. Flexure Spring Design • Modeled as seen on McMaster’s website • Specific dimensions not given, so spring constant is not known • Plan on purchasing part, and testing to determine k-value, otherwise, machine our own part

  24. PID Controller

  25. Voltage Controlled Current Source

  26. Sensor Design • The sensor is based on the idea of a varying capacitance by using 2 metal plates close to each other • One is stationary while the other moves with the mirror moves. • As the plate moves the capacitance changes and changed the impedance of the circuit. • An Impedance converter creates an equivalent resistance. • A Wheatstone bridge circuit is used to find the variation of the impedance in terms of a voltage. • The voltage VG Is then supplied back to the control circuitry to use as feedback.

  27. Sensor Design (cont.)

  28. Power Regulator

  29. Test Plan • Pre-assembly and construction test plan: • Makes sure that customer needs and engineering specs are met in pre-assembly stage • Serves as a quality control procedure, in order to eliminate defects at early stage • Mistake proofing • Example: testing PCB, voice coil functionality, measuring important part dimensions. • Final product test plan • Shows if all the customer needs and specs met by final product • Displays if there are functionality issues that needs to be eliminated prior delivery • Examples: testing slew rate, settling time, power consumption, tilt range.

  30. Test Plan cont. Final Product Testing Tasks

  31. MSD II Project Plan

  32. Bill of Materials Note: Additional items will be added as necessary

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