UNC ROVERSAT IV

University of Northern Colorado

Critical Design Review

Friday, June 25 2010

UNC ROVERSAT IV

Mission Overview:

• 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 Objective:

1. Using a COTS Accelerometer determine when the payload has landed.

2. Upon landing determine that conditions are stable (no movement) and begin deployment.

3. Deploy a rover by first opening the payload then activating the rover.

4. Rover will then exit the payload and begin operations.

UNC ROVERSAT IV

Mission History:

• 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

RoverSat I

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 II

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 III

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

Support From Frontiers of Science Institute:

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

RoverSat IV Design Features:

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 Mechanical Hardware:

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 Latch Mechanism:

Small linear actuator provides motion to un-lock “bolt”

LockedOpen (Pin in locked

position)

UNC ROVERSAT IV

RoverSat IV Deployment Mechanism:

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 Box Materials:

Sandwich Foam Carbon Fiber Sheet

This material is very rigid for its weightAvailable from Hobby Stores online

Tongue and groove construction improves reliability.

Cargo Strapping will provide the hingeMaterial for the box.

UNC ROVERSAT IV

RoverSat IV Box Dimensions:

Box Dimensions:

UNC ROVERSAT IV

RoverSat IV Rover Construction:

All Parts are 2D and can be cut on laser table for quick production.

UNC ROVERSAT IV

RoverSat IV Rover Suspension:

Rocker-bogie design provides superior traction with minimal effort.

UNC ROVERSAT IV

RoverSat IV Rover Dimensions:Side View

UNC ROVERSAT IV

RoverSat IV Rover Dimensions:Bottom View

UNC ROVERSAT IV

RoverSat IV Electronics:

“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 (Box) :

Arduino pro

ADXL213AE

ADCPWM

Linear Actuator

UART

UNC ROVERSAT IV

RoverSat IV Software (Box) :

Description: 1. Program begins with 1.5hr sleep cycle.2. Sleep cycle exits

1. Accelerometer measures 2 axis2. Accelerometer makes about 100 measurements over 30

seconds3. Arduino calculates standard deviation.4. If standard deviation is acceptable for landing program

proceeds to deploymene3. Linear actuator is drawn in by arduino, unlocking the payload

doors.4. Servo pushes the doors open for rover to exit.5. Xbee radio sends communication to rover telling it to deploy.

UNC ROVERSAT IV

RoverSat IV Electronics (Rover) :

Arduino pro

ADCPWM

Motors

UARTIR Ranger

UNC ROVERSAT IV

RoverSat IV Software (Rover) :

Description: 1. Program begins with sleep cycle.2. Sleep cycle exits when told by main box through Xbee radio3. Rover begins automated deployment routine4. Rover then enters autonomous mode for exploration5. If accessed by user through Xbee rover can switch from

autonomous to manual mode.

UNC ROVERSAT IV

RoverSat IV Major Parts List:

“Box”- mechanical

carbon fiber foam plate

delrin plasticaluminum angle

ironcargo strap

materiallinear actuatorjoint assemblylarge servodeployment

mechanism

- electrical7.4 lipoly pack

1000maharduino proADXL Series

AccelerometerXbee wireless radio

Rover- mechanical

delerin plate for chassis

50:1 Copal motors2” Light flight tires¾” standoffs

- electrical7.4 lipoly pack

1000maharduino proSharp

Irvrangefindermotor controllerXbee wireless radio

UNC ROVERSAT IV

RoverSat IV Testing :

Tests to be performed:1. Drop Test (15 ft)2. Cold Test (70f to -70f over one hour)3. Deployment testing (Premature)4. Deployment testing (Ideal)5. Deployment testing (Non-Ideal)6. Rover test drive (Terrain evaluation)7. Day in life test (Full program, full environment)

UNC ROVERSAT IV

RoverSat IV Mass Breakdown :

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