1. Group D ECE 496: Gyrobot Project Ray Price Matt Vaughn Cyrus Griffin
David Epting
John Abbott

2. Introduction
The Gyrobot is an underactuated pendulum, consisting of a single link with a flywheel driven by a dc motor mounted at the free end.

3. Topics Group Structure / Schedule Project Specifications Mechanical
Design
Fabrication
Status
Problems
Software
Webpage
Future Plans

4. Group D Structure Ray Price – Group Leader
Matt Vaughn – Software Design
Cyrus Griffin – Software Design
John Abbott – Mechanical Design
David Epting – Mechanical Design

5. Group D Structure
Gant Chart

6. Project Specifications
The Gyrobot had to fit the following criteria:
Must comply to the mechanical specification of thesis by Adrian Jenkyn Lee out of the University of Illinois at Urbana-Champaign.
Must utilize motor/flywheel inertia to invert pendulum and then balance.
Utilizes Simulink RTW controller.

7. Mechanical The Gyrobot shaft: Design Fabrication Status Problems
Dimensions: 18”
Material: Aluminum
Mounting: threaded shaft utilizing 3/8” nuts and a lock washer
Fabrication
Milliken
Status
The arm is in place with motor attached
Problems
None

8. Mechanical The Gyrobot arm: Design Fabrication Status Problems
Shape: Dumbbell shape
Dimensions:
17 ½’’ long
¼’’ thick
½’’ wide along shaft
¾’’ radius at circular ends and center
Material: Aluminum
Mounting: held onto threaded shaft with 2 3/8” nuts and a lock washer
Fabrication
Milliken
Status
The arm is in place with motor attached
Problems
None

9. Mechanical The flywheel Design Fabrication Status Problems Dimensions
3 ½’’ total radius
2 ½’’ radius to lip
½’’ thick at lip
¼’’ thick inside lip
Material: Brass
Mounting: Pressed onto motor
Fabrication
Milliken
Status
The flywheel is currently attached to the motor
Problems
A bit of wobble, but hopefully not detrimental.

10. Mechanical Position Encoder: Product: Current Status Problems
Arm position/speed Encoder: US Digital E3
Stats: 1024 CPR
Mounted utilizing USD mounting plate and metal bracket.
Current Status
The Encoder is attached to the Gyrobot shaft and operational
Problems
Encoder was a tight fit onto shaft

11. Mechanical The Motor: Pittman 9237S011 Problems Current Status
No Load Speed: 5,331 rpm
Continuous Torque: 11.5 oz-in
Peak Torque: 77 oz-in
Weight: 19 oz
Motor is mounted to base by screws
Encoder:
3 Channels with 500 CPR
Problems
Arrival Time
Bad Encoder
Current Status
New Motor should be here Thursday

12. Mechanical Base Large piece of channel iron
Used because of weight and cost
Unistrut is utilized to secure bearings and position encoder base
Position encoder is attached to a piece of 1/32” sheet steel bent at a 90 degree angle with slot cut in middle for shaft connection
Position encoder base is attached to a perpendicular piece of unistrut mounted with 4-40 screws which is mig welded to the base.
Fabrication was done by Milliken
Problems
Did not sit stable on the table
Current Status
Base was attached to the table using 2 C clamps and rubber matting was placed underneath to help stabilize
Gyrobot base is stable and robust

13. Mechanical Bearings ½” Pillow block bearings manufactured by NKB
Brass sleeves were used to reduce the size down to the 3/8” shaft size
Bearings are mounted to base via a perpendicular piece of unistrut which is mig welded to the base
Bearings were pressed onto unistrut
Problems
Brass sleeves were difficult to install
Bearings were tight after sleeves were installed
Current Status
Bearings were reeled and aligned which created a good fit
Arm swings freely with little resistance

14. Software Collocated Swing Up Non-Collocated Swing Up
Sinusoidal Swing Up

15. Software Swing Up Control Status Problems
Decided to go with the Sinusoidal Swing Up
Smoother
Faster due to the harmonics
Less bouncing in controls compared to other two.
Problems
Deciding to use radians or degrees for the angle

17. Software Switch from Swing up to balance Design Problems Position
Speed factor
Problems
Determining the negative and positive angle and how the computer will be able to distinguish quickly.
Determining where the cut off angle is going to be for swing-up and balancing.

19. Software
Balance Control - The Model

20. Balance Control Important Variables: Arm position (theta 1)
Arm velocity (theta dot)
Flywheel velocity (theta2dot)

21. Balance Control Arm Position
Must add enough energy to move mass of assembly to the highest position.
Fighting gravity
Gain based on center of gravity and mass of the mobile assembly (motor, flywheel, arm, shaft).
Considering trying using cosine function to expand functional range (making it a non-linearized system).

22. Balance Control Arm Velocity
First goal is to have the arm slow as it approaches vertical.
Second goal is to have arm fight acceleration if it falls away from vertical.
Gain based on rotational inertia of the whole mobile system.

23. Balance Control Flywheel Velocity
Goal is to stop the flywheel when the arm is balancing.
Gain made to be small, in effect creating an underdamped system, so slowing the flywheel doesn’t seriously affect the balance.
Gain is negative to bring the speed of the flywheel to zero (instead of slowly ramping up).

24. Encoder Processing Getting Velocity from Position
Obvious way is by taking derivative of position, but there are limitations in simulink.
So, better solution, and solution used in the thesis, was to estimate the derivative through a frequency-domain formula.
This yields far more smooth, continuous results than the built-in derivative functional block.

25. Webpage

26. Future Plans Replace Motor
Ensure action of Windows/Simulink environment
Finish balancing routine
Finish swing up / switching routine