project completion ece 496 fall 2002 gyrobot team d
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Project CompletionProject CompletionECE 496 Fall 2002ECE 496 Fall 2002
GyrobotGyrobotTeam DTeam D
OutlineOutline The Group/Team The Project Design Specifications Design Approach Main Model / Encoders Balance Control Swing-up Control Hardware Challenges Software Challenges Performance Summary Questions
TeamTeam
Ray Price – Team LeaderRay Price – Team Leader David Epting – Hardware David Epting – Hardware
Designer / WebmasterDesigner / Webmaster John AbbottJohn Abbott -- Hardware -- Hardware
Designer / Presentation Designer / Presentation ManagerManager
Matt Vaughn – Lead Matt Vaughn – Lead Software Designer / Software Designer / Electronics TechnicianElectronics Technician
Cyrus Griffin – Software Cyrus Griffin – Software Designer / PhotographerDesigner / Photographer
The ProjectThe Project The Gyrobot is an underexcited The Gyrobot is an underexcited
pendulum, consisting of a pendulum, consisting of a single link (arm) with a flywheel single link (arm) with a flywheel driven by a dc motor mounted driven by a dc motor mounted at the free endat the free end
The Gyrobot was to include a The Gyrobot was to include a control algorithm that uses the control algorithm that uses the generated inertia of the generated inertia of the flywheel to cause the pendulum flywheel to cause the pendulum to invert and balance with the to invert and balance with the flywheel at the 12 o’clock flywheel at the 12 o’clock PositionPosition
Project SpecificationsProject Specifications The Gyrobot had to fit the following criteria:The Gyrobot had to fit the following criteria:
Must comply to the mechanical specification of Must comply to the mechanical specification of thesis by Adrian Jenkyn Lee out of the thesis by Adrian Jenkyn Lee out of the University of Illinois at Urbana-Champaign.University of Illinois at Urbana-Champaign.
Must utilize motor/flywheel inertia to invert Must utilize motor/flywheel inertia to invert pendulum and then balance.pendulum and then balance.
Utilizes Simulink RTW controller.Utilizes Simulink RTW controller.
Design ApproachDesign Approach
Specified / developed hardwareSpecified / developed hardware Procured hardwareProcured hardware Assembled GyrobotAssembled Gyrobot Tested interfaces (encoders and analog Tested interfaces (encoders and analog
output)output) Compiled Encoder / Main RoutineCompiled Encoder / Main Routine Compiled Balance Routine and TestedCompiled Balance Routine and Tested Compiled Swing-up Routine and TestedCompiled Swing-up Routine and Tested
Design ApproachDesign Approach
Gantt ChartGantt Chart
Main Software Model
The main software model combined the encoders, swing-up and balancing algorithms.
Position EncoderPosition Encoder
Used to produce arm position (theta\1 Used to produce arm position (theta\1 from 0 to 2pi and a theta1 from –pi to from 0 to 2pi and a theta1 from –pi to
pi) also produced the arm velocity pi) also produced the arm velocity theta1dot.theta1dot.
Motor EncoderMotor Encoder
Converts number of swings to radian and filters to produce a theta2dot—the flywheel velocity.
SoftwareSoftware Pd Balance Control - The ModelPd Balance Control - The Model
Balance ControlBalance Control
Important Variables:Important Variables: Arm position Arm position
(theta 1)(theta 1) Arm velocity Arm velocity
(theta1dot)(theta1dot) Flywheel velocity Flywheel velocity
(theta2dot)(theta2dot)
Balance ControlBalance Control
Arm PositionArm Position Added enough energy to move mass of Added enough energy to move mass of
assembly to the highest position--Fighting assembly to the highest position--Fighting gravitygravity
Gain of kp = 3.375 was used based on center Gain of kp = 3.375 was used based on center of gravity and mass of the mobile assembly of gravity and mass of the mobile assembly (motor, flywheel, arm, shaft)(motor, flywheel, arm, shaft)
Balance ControlBalance Control
Arm VelocityArm Velocity As the arm approached vertical it should slow. As the arm approached vertical it should slow.
Arm must be able to fight acceleration if it falls Arm must be able to fight acceleration if it falls
away from vertical.away from vertical. Gain of kd = .72 based on rotational inertia of Gain of kd = .72 based on rotational inertia of
the whole mobile system. the whole mobile system.
Balance ControlBalance Control
Flywheel VelocityFlywheel Velocity The flywheel stopped when the arm is The flywheel stopped when the arm is
balancing.balancing.
Gain of k = .0006 was small, in effect Gain of k = .0006 was small, in effect creating an under-damped system.creating an under-damped system.
Gain is negative 175 (after the summer) to Gain is negative 175 (after the summer) to bring the speed of the flywheel to zero bring the speed of the flywheel to zero (instead of slowly ramping up).(instead of slowly ramping up).
Swing Up ControlSwing Up Control
Sinusoidal model from thesis was used Sinusoidal model from thesis was used because:because:
SmootherSmoother Faster due to harmonicsFaster due to harmonics Less bouncing in controls compared to other Less bouncing in controls compared to other
proposed methodsproposed methods
Swing Up ControlSwing Up Control
Sends a sinusoidal signal to the motorSends a sinusoidal signal to the motor
Motor switches polarity via a switch when the Motor switches polarity via a switch when the arm reaches zero velocityarm reaches zero velocity
Theoretically the control effort is supposed to Theoretically the control effort is supposed to slow down as balance is approached, but since slow down as balance is approached, but since we saturated the effort this doesn’t really happen we saturated the effort this doesn’t really happen
Mechanical Design ChallengesMechanical Design Challenges
FlywheelFlywheel ProblemsProblems
Flywheel was not properly centered during milling Flywheel was not properly centered during milling processprocess
Wheel would wobble and eventually flew offWheel would wobble and eventually flew off
SolutionSolution A glue was applied along with the set screwA glue was applied along with the set screw
The glue absorbed most of the vibration, drastically The glue absorbed most of the vibration, drastically reducing the wobblereducing the wobble
Mechanical Design ChallengesMechanical Design Challenges
Pittman MotorPittman Motor ProblemsProblems
While pressing the flywheel onto the motor the encoder was While pressing the flywheel onto the motor the encoder was pushed off-centerpushed off-center
Heat generated during use led to inconsistent performanceHeat generated during use led to inconsistent performance
SolutionSolution A new motor was ordered in exchange for the damaged one A new motor was ordered in exchange for the damaged one
and the flywheel was attached by a set screw instead of and the flywheel was attached by a set screw instead of being pressed onbeing pressed on
Followed a set timing scheduleFollowed a set timing schedule
Mechanical Design ChallengesMechanical Design Challenges
BearingsBearings
ProblemsProblems Bearings were too stiff, generating un-needed Bearings were too stiff, generating un-needed
friction friction
SolutionSolution Bearings eventually loosened up after useBearings eventually loosened up after use
Control Challenges - BalanceControl Challenges - Balance
Problem: Parameter OptimizationProblem: Parameter Optimization Solution: Optimize only 1 control variable Solution: Optimize only 1 control variable
at a timeat a time
Control Challenges - BalanceControl Challenges - Balance
Problem: Limited Pull-up abilityProblem: Limited Pull-up ability Solution: Create a window outside of Solution: Create a window outside of
which the routine does not engage. which the routine does not engage.
Control Challenges – Swing-upControl Challenges – Swing-up
Problem: Recovery time between runs.Problem: Recovery time between runs. Solution: Use a 4-swing swing-up. Solution: Use a 4-swing swing-up.
Allow cooling time.Allow cooling time.
Control Challenges - SwingupControl Challenges - Swingup
Problem: Inconsistent effort window.Problem: Inconsistent effort window. Solution: Set window each day based on Solution: Set window each day based on
the temperature of the room, and the the temperature of the room, and the temperament of the gyrobot.temperament of the gyrobot.
Control Challenges - Control Challenges - TransitionTransition
After a repeatable swing-up was established, there After a repeatable swing-up was established, there were still problems with the transition to balance. were still problems with the transition to balance.
Problem: Inconsistent room temperature.Problem: Inconsistent room temperature. Solution: Practice the routine enough times on Solution: Practice the routine enough times on
competition day to get a “feel” for cooling time.competition day to get a “feel” for cooling time.
PerformancePerformance
Final CompetitionFinal Competition Fastest time – 2.47 seconds (2Fastest time – 2.47 seconds (2ndnd Place) Place)
Bonus DayBonus Day 9 out of 109 out of 10
SummarySummary
Were able to build a gyrobot device and Were able to build a gyrobot device and the associated control structure that would the associated control structure that would invert and balance the gyrobot penduluminvert and balance the gyrobot pendulum
Able to balance and resist impulsive forces Able to balance and resist impulsive forces against the deviceagainst the device
Able to “swing-up” in 4 swings.Able to “swing-up” in 4 swings.
Questions?Questions?