Epitaxy of Wide-Bandgap Semiconductors
Just a normal Smart carHsiang (Jeff) Hsu, Anthony Pope1 December
2016A car that monitors its location and avoids obstacles to get to
any given (x,y) point
1
ObjectiveGiven a set destination, the car will be able to detect
obstacles, maneuver around them, and reach the desired location
within 5 cm.
Tasks : Record position of car using IMU sensor and encoderUse
ultrasonic sensor to sense obstaclesManeuver around obstaclesUse
control loop to drive car to goal
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Design - Steering AssemblyServo Powered ControlServo Horn
Connector2 connecting Linkages2 pivoting LinkagesLinkage Caps3
Design - Rear Axle Assembly2 3D-Printed bearings3D-Printed Motor
MountMicro DC motor (1:150)2 gears for increased torque (1:2)
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Design - HousingLaser Cut from poplar wood5
Design - Electronics MSP432 MPU 9250 IMU unit Servo motor
HC-SR04 Ultrasonic Sensor 6V DC micro motor w/ Encoder 9V battery
for DC motor Power 5V DC MyCharge rechargeable battery
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Design - Circuitry7
Servo
PWM
Encoder Power
Sensor Power
Sensor Output Voltage Divider
Common Ground
Breadboard A - Motor Driver from Lab Breadboard B - Servo,
Encoder, and Sensor
Design Final Prototype8
Block Diagram9MSP 432Ultrasonic SensorDC MotorEncoderServo
MotorRising/Falling edge (digital input) triggers Interrupt and
updates positionPWM signal (servo angle)PWM signal through
H-BridgeDigital pulse generated and sent to sensor
transmitterDigital pulse received and sent to MCUControl Loop is
run on timer - updates servo angle based on positionPosition is
updated within encoder interrupt based on mathematical modelIMU
MagnetometerArduinoSerial Communication
Original Mathematical ModelingEncoder to distance Servo angle to
radius of curvatureStraight line position update equationTurning
position update equation10
New Mathematical Modeling11
given by IMU magnetometerD given by encoder reading
Control Algorithm Run control loop Move forward until an object
is < 60cm Turn until the object is no longer visible Continue
turning for x sec Run control on angle to get to Set position
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Control Algorithm
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Results
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Result Back Up Slide15
Future WorksImprove the real-world position mapping
accuracyImprove control algorithm tuning (PD, PID)Implement more
true Ackermann steering geometryAdd differential gear, or 2
separate motors to eliminate rear wheel slipperageImplement speed
control and reverse direction
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Questions?17
