Build to kick kick to win

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Shooting skills

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Outline

Shooting mechanismSystem descriptionActuator design

Lob shotsIdentificationCalibration

Towards controlled shootingProblem descriptionProposed implementation

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Shooting mechanism

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Requirements and specifications

Requirements:• Controllable• Hard / soft• Lob / flat• Repeatable

Specifications• vf = 9ms-1

• xf = 90 mm

• tf = 20 ms• a ≈ 450 ms-2

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System description

Robotbattery

DC DC

ActuatorMechanicaltransmission

BallC

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Actuator design

Mechanical design

Electromagnetic design

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Actuator design

Investigated aspects• Saturation• Eddy currents• Losses• Thermal issues

2.4T

1.5T

Meessen, K.J., Paulides, J.J.H. & Lomonova, E. (2010). A football kicking high speed actuator for a mobile robotic application. Proceedings of the 36th Annual Conference of the IEEE Industrial Electronics Society, IECON 2010, 7-10 November 2010, Glendale, Arizona, (pp. 1659-1664).

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Actuator design

Final design• Total mass: 4.5 kg• Peak force: 700N• Peak current: 110A

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Outline

Shooting mechanismSystem descriptionSolenoid actuator design

Lob shotsIdentificationCalibration

Towards controlled shootingProblem descriptionProposed implementation

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Lob shots: trajectory

Largest gradient possible

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Lob shots: identification

Each actuator has its own actuator characteristic

General function between distance and duty cycle:

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Lob shots: calibration

Measure distance • For accurate fit at least 3

measurements are necessary

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Lob shots: calibration

Manual calibration using a Matlab gui• For accurate fit at least 3 measurements

are necessary

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Lob shots: tuning

The perfect lob shot• Shoot just under de goal crossbar • Lob trajectory depends on distance ball to the goal

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Lob shots: tuning

The perfect lob shot• Shoot just under de goal crossbar • Lob trajectory depends on distance ball to the goal

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Outline

Shooting mechanismSystem descriptionSolenoid actuator design

Lob shotsIdentificationCalibration

Towards controlled shootingProblem descriptionProposed implementation

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Problem description

Increasing ball output speed accuracy• Currently a large variation between Turtles

– Makes tuning difficult

• Current relation between kick-effort and ball output speed is not linear– Also increases tuning complexity

• Current system is open-loop– Tuning per Turtle is possible, though time consuming

• Desired: more predictable behavior– Tuning effort/time decreases– More linear behavior– Decrease of variation between Turtles

Proposed implementation

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Ball

Encoder

Solenoid

Plunger

Lever

Amplifier +Actuator

Control algorithm

Encoder

PC + IO stack

PWM signal

Encoder value

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Proposed implementation

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Proposed implementation

Controlling the lever speed• Both time and encoder resolution

pose limitations• Due to design of solenoid 'braking' is

not possible: speed overshoot is not allowed

• Main idea is to 'guide' lever + ball to end speed, instead of kicking/hitting

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Proposed implementation: simulation

Current situation

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Proposed implementation: simulation

Proposed solution

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Summary and conclusions

• Design and optimization of the shooting mechanism

• Identified an exponential relation between the duty cycle and kicking distance for lob shots

• Lob shot calibration using an graphical user interface

• Feedback control design for the output speed of the ball

• Modeling and simulation of the feedback controlled shooting mechanism

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Thank you for your attention