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This project focuses on designing a workable RC car from scratch with speeds exceeding 100 mph. It involves creating a GUI interface for laptop control, developing a mechanical chassis and shell, and implementing a power system using LiPo batteries.
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Critical Design Review MACH 1/7 Daniel Bressan David Tran Robbie Banks Amit Kapoor
Overview • Produce an awesome workable RC car from scratch • Top speeds of over 100 mph • Program GUI interface to control the car from laptop • Design mechanical chassis and shell for car David Tran
Target Goals • Low: Function Car • Using ECS pre-programmed chip • Driving, with GUI and 900MHz RF • Low end (cutting board) Chassis • Mid: 30-50 MPH • Gate drivers working • High: 100+ MPH • Build own Chassis and Shell David Tran
The Plan v2.0 David Tran
Input • We will build a GUI interface to control the car. • Mouse • Keyboard • Input: • Power from wall • RS-232 Signal for speed • Output: • RS-232 Signal to CPU to control speed and steering • Will start coding as soon as PCB is ordered Amit Kapoor
RF System • Not much changed since PDR • Xtend PKG - 900 MHz • Tested and working Amit Kapoor
Micro Controller David Tran
MSP430 • MSP430-F2616 • Inputs Tx/Rx and digital optical encoder information • Outputs PWM for servo and PWMs for gate driver • MAX232 • Interprets RS-232 signal David Tran
PWM for Sinusoids/Servo • User timers and DAC to generate sinusoid • Pulse widths from sin table • Servo Control David Tran
Power System Daniel Bressan
Power System Daniel Bressan
Power • LiPo 3 cell 11.1 V • Powers motors and everything isolated on that side • LiPo 4 cell 14.8 V • Regulated for: • 3.3 V TLV-1117 33 • 5 V TLV-1117 50 • 9 V LM2940 9.0 Daniel Bressan
Power – Level 2 • 14.8 V, 1Ah LiPo regulated for: • 3.3 V MSP430 • 5 V • Optical Encoder • Max 232 • 9 V RF • 11.1V, 5Ah LiPo Motor side • 5 V • Optoisolater VO0630T (right) • DC motor for Gyroscope • Servo • Transistors Daniel Bressan
Control • Speed Encoders • US Digtial E5 • 32 CPR (cycles per revolution) • Max RPM 60,000 • Sensors • NONE! • Threw out inclinometer and force sensor ideas • Steering • Pre-Built Servo • PWM • Gyroscope Daniel Bressan
Motor – Mamba Monster • Takes three PWM inputs • Max RPM of 60 kHz • Four pole motor • Max input frequency 2kHz • RPMs can be calculated as follows RPM = 120 * f/p p = poles • With our wheels and rotational speed we could achieve a velocity of 700 MPH Robbie Banks
Torque Curves • Constant torque up to the rated frequency • Can go past rated frequency but lose torque Robbie Banks
Motor Driver • Dual Channel Opto-Isolators • Gate Driver • Triple Half-Bridge Driver Robbie Banks
Motor Driver Robbie Banks
Opto-Isolators – VO0630T • Using Opto-Isolator for separation • Powered by a regulator connected to the motor power supply • Takes PWM inputs from microcontroller • Digital Opto-Isolator high-low threshold of .8V • Rise time of 23ns and Fall time of 7ns • Max frequency of 33.3MHz Robbie Banks
Gate Driver – HIP4086 • Three PWM inputs • Amplifies PWM inputs • Dead time setting to prevent shoot through • Disable input signal • Six output signals, three high and three low • Powered directly by the three cell 11.1V LiPo battery Robbie Banks
Triple Half Bridge Driver • Uses six AUIRL1404ZS MOSFETS • High Power NMOS transistors • Continuous drain current of 160A • VGS of 10V • Each source on the MOSFET is connected to the gate driver to ensure a VGS of at least 10V • Powered directly from the three cell 11.1V LiPo battery Robbie Banks
Mechanical • For testing and low level design: • Kitchen cutting board chassis • High level design (after machine shop training): • Chassis and Shell possibly out of acrylic. • ITLL has an acrylic cutter • Will start full designs after PCB is ordered this week Robbie Banks
Division of Labor • Main Changes: • David: mostly software, getting PWMs to work properly • Amit: Learning and teaching us Altium, and software with David • Robbie: Gate Driver and Power • Daniel: Power, and other simple components, helping Robbie Amit Kapoor
Schedule • Changes to Schedule: • Behind on ordering PCB (should finish this week) • Behind on programming GUI, will start as soon as PCB is ordered • Ahead of schedule for gate driver Amit Kapoor
BudgetUsed so far (Parts List) Amit Kapoor
Deliverables • Milestone I • PCB testing (hopefully we’ll have it back) • Working Gate Driver • MSP430 communicating with gate driver • Milestone II • Driving Car • EXPO! • Car going 100+ MPH Amit Kapoor
ANYQUESTIONS? Daniel Bressan