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UNC RoverSat IV

UNC RoverSat IV. University of Northern Colorado Critical Design Review Friday, June 25 2010. To sucsefully deploy an autonomous rover from a balloon payload. To improve upon previous RoverSat missions by reducing mass.

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UNC RoverSat IV

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  1. UNC RoverSat IV University of Northern Colorado Critical Design Review Friday, June 25 2010

  2. To sucsefully deploy an autonomous rover from a balloon payload. • To improve upon previous RoverSat missions by reducing mass. • To improve upon previous RoverSat missions by increasing reliability. • To engage highschool students in the design and testing of a Balloon payload. UNC RoverSat IV Mission Overview:

  3. Using a COTS Accelerometer determine when the payload has landed. Upon landing determine that conditions are stable (no movement) and begin deployment. Deploy a rover by first opening the payload then activating the rover. Rover will then exit the payload and begin operations. UNC RoverSat IV Mission Objective:

  4. The RoverSat project has been on going for the last 4 years at UNC. • Three payloads have been built using similar methods of sensing and deployment. • The payloads have deployed successfully but in all cases the rover has failed to leave the box. • Each failure has demonstrated new problems in payload “Box”designs. • Other failures included the failure of activation devices. UNC RoverSat IV Mission History:

  5. RoverSat I – First Attempt at rover payload Sucsesses – Gained video footage of flight and box sucssessfully opened Failures – Rover activated early in the flight causing batteries to be drained before landing. UNC RoverSat IV RoverSat I

  6. RoverSat II – Attempted to integrate camera into rover for flight and operation. Sucsesses – Gained video footage of flight and box sucssessfully opened. Failures – Rover activated early in the flight. Rover also was damaged by rough landing. UNC RoverSat IV RoverSat II

  7. RoverSat III – Attempt at rover simplification and deployment mechanism revisited. Sucsesses – Box successfully opened Rover successfully activated. Failures – Rover failed to leave box due to software failure involving obstacle avoidance sensors. UNC RoverSat IV RoverSat III

  8. This will be the first year FSI students will assist in a balloon project. FSI students have been developing the concept and designs for the latch mechanism and over all box design. UNC RoverSat IV Support From Frontiers of Science Institute:

  9. RoverSat IV – We intend to improve on the design of RoverSat III with a new type of locking latch. The former payloads relied on a fishing line that was destroyed to “un-lock” the box. This is being replaced with a non-destructive linear actuator and dead-bolt method. The rover will have a wireless communication path to the box to prevent premature activation. Activation will only come after the doors are verified to be open. This will also enable ground support to manually deploy the rover in the event of an autonomous failure. UNC RoverSat IV RoverSat IV Design Features:

  10. Two Components: “Box” – Rover enclosure and deployment - Mechanical latch to ensure box remains closed during flight - Mechanical device to open box facilitating deployment - Use of composites to decrease weight of payload Rover – Small autonomous rover to be deployed - Light weight plastic design - Small rocker-bogie design for traction - Press fit frame for quick assembly and durability UNC RoverSat IV RoverSat IV Mechanical Hardware:

  11. Small linear actuator provides motion to un-lock “bolt” UNC RoverSat IV Locked Open (Pin in locked position) RoverSat IV Latch Mechanism:

  12. A servo will be used to push the box open. The servo will have an arm and two push rods much like RoverSat III. UNC RoverSat IV RoverSat IV Deployment Mechanism:

  13. Sandwich Foam Carbon Fiber Sheet This material is very rigid for its weight Available from Hobby Stores online Tongue and groove construction improves reliability. Cargo Strapping will provide the hinge Material for the box. UNC RoverSat IV RoverSat IV Box Materials:

  14. Box Dimensions: UNC RoverSat IV RoverSat IV Box Dimensions:

  15. All Parts are 2D and can be cut on laser table for quick production. UNC RoverSat IV RoverSat IV Rover Construction:

  16. Rocker-bogie design provides superior traction with minimal effort. UNC RoverSat IV RoverSat IV Rover Suspension:

  17. Side View UNC RoverSat IV RoverSat IV Rover Dimensions:

  18. Bottom View UNC RoverSat IV RoverSat IV Rover Dimensions:

  19. “Box” – Electronics for the box will be based around the arduino pro. - Accelerometer - Door Lock actuator - Deployment mechanism actuator - Xbee Radio (Communication between rover and box) Rover – Electronics for the rover will be based around the arduino pro. - Motor Controllers - IR sensors (Obstacle avoidance) - Xbee Radio (Communication between rover and box) UNC RoverSat IV RoverSat IV Electronics:

  20. ADC PWM ADXL213AE UART Arduino pro Linear Actuator UNC RoverSat IV RoverSat IV Electronics (Box) :

  21. Description: • Program begins with 1.5hr sleep cycle. • Sleep cycle exits • Accelerometer measures 2 axis • Accelerometer makes about 100 measurements over 30 seconds • Arduino calculates standard deviation. • If standard deviation is acceptable for landing program proceeds to deploymene • Linear actuator is drawn in by arduino, unlocking the payload doors. • Servo pushes the doors open for rover to exit. • Xbee radio sends communication to rover telling it to deploy. UNC RoverSat IV RoverSat IV Software (Box) :

  22. ADC PWM UART Arduino pro Motors IR Ranger UNC RoverSat IV RoverSat IV Electronics (Rover) :

  23. Description: Program begins with sleep cycle. Sleep cycle exits when told by main box through Xbee radio Rover begins automated deployment routine Rover then enters autonomous mode for exploration If accessed by user through Xbee rover can switch from autonomous to manual mode. UNC RoverSat IV RoverSat IV Software (Rover) :

  24. “Box” - mechanical carbon fiber foam plate delrin plastic aluminum angle iron cargo strap material linear actuator joint assembly large servo deployment mechanism - electrical 7.4 lipoly pack 1000mah arduino pro ADXL Series Accelerometer Xbee wireless radio Rover - mechanical delerin plate for chassis 50:1 Copal motors 2” Light flight tires ¾” standoffs - electrical 7.4 lipoly pack 1000mah arduino pro Sharp Irvrangefinder motor controller Xbee wireless radio UNC RoverSat IV RoverSat IV Major Parts List:

  25. Tests to be performed: Drop Test (15 ft) Cold Test (70f to -70f over one hour) Deployment testing (Premature) Deployment testing (Ideal) Deployment testing (Non-Ideal) Rover test drive (Terrain evaluation) Day in life test (Full program, full environment) UNC RoverSat IV RoverSat IV Testing :

  26. Mass Budget: Rover – 500g -motors 200g -battery 100g -wheels 40g -electronics 60g -chassis 100g Box – 1000g -locking mechanism 200g -deployment mechanism 250g -battery 100g -electronics 60g -chassis 390g UNC RoverSat IV RoverSat IV Mass Breakdown :

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