Electrical and Computer Engineering Cumulative Design Review Team 22: Driver Assist

2 Electrical and Computer Engineering Primary Solution  Our solution is to create a joystick that mechanically controls the steering wheel, brakes, and throttle  The joystick will pivot horizontally allowing the driver to turn left and right.

3 Electrical and Computer Engineering Block Diagram

4 Electrical and Computer Engineering CDR Deliverables Steve Cook:  3D print top half of the joystick  Install hand brake and throttle Sam Burke:  Implementation of gear train  Mount gear train to drive steering wheel  3-D printed gears Andrew Klinkowski:  Full control over DC motor at required spec of 1.5rps  Aid in the 3D design of joystick Qingchuan Wu:  Charger optimization increased to 85%  Power supply rails well regulated

5 Electrical and Computer Engineering Old Joystick Design -Heavy -Loose tension on brake and throttle -Throttle felt small and uneasy to use

6 Electrical and Computer Engineering New Joystick Design

7 Electrical and Computer Engineering Brake Prototype  The brake stops the car and control reverse in the video game. Includes: potentiometer, wire, and hand brake Potentiometer sends a voltage reference between 0.58V to 4.5V depending on depression of hand brake Higher voltage corresponds to harder braking 10k Potentiometer is used to reduce power and maximize voltage reference swing.

8 Electrical and Computer Engineering Throttle Voltage Mapping  The video game controller maps 0 acceleration at 3.92V and increase until it hits max acceleration at 0V.  The throttle used maps 0.886V before acceleration and 4.33V for max acceleration.  A circuit was designed to mapped the throttles.886V to the games input of 3.92V.  And to take the throttles max acceleration voltage 4.33V and map it to 0V.

9 Electrical and Computer Engineering Voltage Mapping Schematic

10 Electrical and Computer Engineering Motor Driver  The driver amplifies the ATmega32’s outputs to be used by the motor

11 Electrical and Computer Engineering Basic Motor Phase control U/V phase excitation A’ = 0 B’= 1 A = 0 B = 1 Flow of current

12 Electrical and Computer Engineering

13 Electrical and Computer Engineering

14 Electrical and Computer Engineering Power – Battery Charger Requirement  Charge external 12V NiMH battery from the cigarette port V input  Limit Charging current below 4A  Limit Charging voltage below 16V

15 Electrical and Computer Engineering Battery Charger  Used to charge external battery pack from 12V car battery

16 Electrical and Computer Engineering Battery Charger Features  Thermal Feedback Shutdown  Input Overload Protection  Input Reverse Polarity Protection  Output short circuit <20s  Charging Completion Indication  Adjustable output

17 Electrical and Computer Engineering Power – Battery Charger Result

18 Electrical and Computer Engineering Battery charger result  80% efficiency at 14V and 2A  Peak output current 6.4A at 8V  Requires heat sink to optimize  Feedback control needs adjustment

19 Electrical and Computer Engineering Power Supply

20 Electrical and Computer Engineering Power – Power Supply  Requirement Provide regulated supply voltage 7.5V for controller Provide 2 isolated voltages 12V for driving Mosfet  Implementations Forward converter PI control on 5V output Transformer and mutual inductors for cross regulation.

21 Electrical and Computer Engineering Power – Power Supply  Requirement Provide regulated supply voltage 7.5V for controller Provide 2 isolated voltages 12V for driving Mosfet  Implementations Flyback converter PI control on 7.5V output Mutual inductance regulation on 12V outputs Current transformer sensing

22 Electrical and Computer Engineering Power – Power Supply Result  Green: 100 ohm Red 20 ohm Blue 24 ohm

23 Electrical and Computer Engineering Motor Selection Current Motor Specifications Speed: rps Torque:.125Nm Brushless DC Requirements to Control Steering Wheel Speed: ~1.5rps Torque: 6Nm

24 Electrical and Computer Engineering Gearing  A gearing ratio of 54 will allow us to have the outputted torque required, while staying close to the required rps. .125Nm * 54 = 6.75Nm  Speed = (4000rpm/60)/54 = rps

25 Electrical and Computer Engineering Gear Train Design  To design a gear train with a 54:1 ratio 4 stages where used.  Stages 1-3 had a 3:1 ratio and stage 4 included a 2:1 ratio  Stages 1-3 were created using a gears with 60 and 20 teeth  Stage 4 was created with gears having 130 and 60 teeth

26 Electrical and Computer Engineering Gear Train Design

27 Electrical and Computer Engineering Gear Train Implementation

28 Electrical and Computer Engineering FDR Deliverables Steve Cook:  3D print bottom half of joystick  Install top and bottom half together  Joystick will have full control over gas/brake and steering wheel Sam Burke:  Mount motor to gear train  Design base for user to sit in  Stabilize gear train Andrew Klinkowski:  Full control over DC motor at required spec of 1.5rps  Process Hall Effect Sensor Data  Drive Motor from PIC controller to PWM stall current Qingchuan Wu:  Charger optimization increased to 85%  Power supply rails well regulated  Complete power system

29 Electrical and Computer Engineering Motor Phase control- Buck (CDR) U/V phase excitation A’ = PWM B’= 1 A = 0 B = 1 Flow of current Normal PWM on PWM off

30 Electrical and Computer Engineering Motor Phase control- Boost (CDR) U/V phase excitation A’ = 0 B’= 1 A = PWM B = 1 Flow of current Normal PWM on PWM off

31 Electrical and Computer Engineering Power – Battery Charger Result R loadVinI inVoutI outP inP out Efficienc y