SkillsUSA Regenerative Car: 2021-22 - State Champion
Over the fall and winter of the 2021-22 school year, I developed a motorized vehicle that is an attempt to expand the regenerative car design. This project was for the Principles of Engineering/Technology competition for SkillsUSA. It won 1st place in the San Jose regional competition and 1st place in the California State Competition for the Principles of Engineering/Technology contest. The project qualified for the national competition in Atlanta, GA, in June 2022, which I chose not to attend.
It features an Arduino, which uses a motor shield and a Bluetooth shield to control and move the car. While the car is moving, the Arduino is gathering raw analog voltage data from two small solar panels and a wind turbine attached to the front of the car. This data is sent to my phone, which is also controlling the vehicle wirelessly. Every component of the car is attached with industrial strength Velcro so I can isolate and work on individual parts with ease.
The purpose of this car is to demonstrate the physics law of conservation of energy. The vehicle is an energy converting machine, with solar panels, a wind turbine, and a battery feeding the motors. My goal with this machine is to demonstrate the conversion of energy types, and extend the regenerative car model to include other types of sustainable electricity in electric/hybrid car designs.
Through this project, I’ve learned a lot about Bluetooth and motors, and how to stack multiple shields when using microcomputers. I’ve spent a lot of time coding for this project to get the Bluetooth to work, and have learned how to better troubleshoot hardware difficulties as well. This project was also done entirely independently, mostly in my Advanced Computer Projects course, and I’m very proud of how I’ve been able to construct something from nothing on my own. Below is the paper I wrote for the competition, my main code, and photos and videos of the vehicle in action!
/*********************************************************************
This is a modified example for our nRF51822 based Bluefruit LE modules
Modified to drive a 3-wheeled BLE Robot Rover! by http://james.devi.to
Pick one up today in the Adafruit shop!
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
MIT license, check LICENSE for more information
All text above, and the splash screen below must be included in
any redistribution
*********************************************************************/
#include <string.h>
#include <Arduino.h>
#include <SPI.h>
#include <Servo.h>
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_MotorShield.h>
#include "utility/Adafruit_MS_PWMServoDriver.h"
#include <Adafruit_BLE_Firmata.h>
#if not defined (_VARIANT_ARDUINO_DUE_X_) && not defined (_VARIANT_ARDUINO_ZERO_)
#include <SoftwareSerial.h>
#endif
// Change this to whatever is the Serial console you want, either Serial or SerialUSB
#define FIRMATADEBUG Serial
// Pause for Serial console before beginning?
#define WAITFORSERIAL false
// Print all BLE interactions?
#define VERBOSE_MODE false
#define TOTAL_PINS NUM_DIGITAL_PINS /* highest number in boards_digitaliopins MEMEFIXME:automate */
#define TOTAL_PORTS ((TOTAL_PINS + 7) / 8)
#include "Adafruit_BLE_Firmata_Boards.h"
#include "Adafruit_BluefruitLE_SPI.h"
#include "Adafruit_BLE.h"
#include "Adafruit_BluefruitLE_UART.h"
#include "BluefruitConfig.h"
#include <Wire.h>
#include <Adafruit_MotorShield.h>
// #include "utility/Adafruit_PWMServoDriver.h"
// #include <Servo.h>
// Create the motor shield object with the default I2C address
Adafruit_MotorShield AFMS = Adafruit_MotorShield();
// Select which 'port' M1, M2, M3 or M4. In this case, M1
Adafruit_DCMotor *L_MOTOR = AFMS.getMotor(3);
// You can also make another motor on port M2
Adafruit_DCMotor *R_MOTOR = AFMS.getMotor(4);
//not used, testing acceleration
// int accelTime = 200;
//Name your RC here
String BROADCAST_NAME = "skillsUSA demonstration vehicle";
String BROADCAST_CMD = String("AT+GAPDEVNAME=" + BROADCAST_NAME);
Adafruit_BluefruitLE_SPI ble(BLUEFRUIT_SPI_CS, BLUEFRUIT_SPI_IRQ, BLUEFRUIT_SPI_RST);
////////////////////////////////////////////////////////////////////////////////////////////////////////////////
int limit = 7 ;
int count = 1;
// A small helper
void error(const __FlashStringHelper*err) {
Serial.println(err);
while (1);
}
// function prototypes over in packetparser.cpp
uint8_t readPacket(Adafruit_BLE *ble, uint16_t timeout);
float parsefloat(uint8_t *buffer);
void printHex(const uint8_t * data, const uint32_t numBytes);
// the packet buffer
extern uint8_t packetbuffer[];
char buf[60];
#define AUTO_INPUT_PULLUPS true
// our current connection status
boolean lastBTLEstatus, BTLEstatus;
// make one instance for the user to use
Adafruit_BLE_FirmataClass BLE_Firmata = Adafruit_BLE_FirmataClass(ble);
/**************************************************************************/
/*!
@brief Sets up the HW an the BLE module (this function is called
automatically on startup)
*/
/**************************************************************************/
void setup(void)
{
Serial.begin(115200);
AFMS.begin(); // create with the default frequency 1.6KHz
// turn on motors
L_MOTOR->setSpeed(0);
L_MOTOR->run(RELEASE);
R_MOTOR->setSpeed(0);
R_MOTOR->run(RELEASE);
Serial.begin(115200);
Serial.println(F("Bluefruit Robot Controller"));
Serial.println(F("-----------------------------------------"));
/* Initialize the module */
BLEsetup();
}
int velocity = 0;
float x, y;
int L_restrict = 0;
int R_restrict = 0;
unsigned long lastAccelPacket = 0;
bool modeToggle = false;
///////////////////////////////////////////////////////////////////////////
bool accelMode(){
if (packetbuffer[1] == 'A') {
x = parsefloat( packetbuffer + 2 );
y = parsefloat( packetbuffer + 6 );
if( x <= -0.55 ){
x += 0.55;
x *= -100.0;
L_MOTOR->run( BACKWARD );
R_MOTOR->run( BACKWARD );
if( x >= 45 ) x = 45;
if( x <= 0 ) x = 0;
velocity = map( x, 0, 45, 0 ,255 );
}
else if( x >= -0.25 ){
x+= 0.25;
x *= 100;
L_MOTOR->run( FORWARD );
R_MOTOR->run( FORWARD );
if( x>= 45 ) x = 45;
if( x<= 0 ) x = 0;
velocity = map( x, 0, 45, 0, 255 );
}
else{
L_MOTOR->run( RELEASE );
R_MOTOR->run( RELEASE );
velocity = 0;
}
//account for L / R accel
if( y >= 0.1 ){
y -= 0.1;
y *= 100;
if( y >= 50 ) y = 50;
if( y <= 0 ) y = 0;
L_restrict = fscale( y, 0.0, 50.0, 0.0, 100.0, -4.0 );
}
else if( y <= -0.1 ){
y += 0.1;
y *= -100;
if( y>= 50 ) y = 50;
if( y<= 0 ) y = 0;
R_restrict = fscale( y, 0.0, 50.0, 0.0, 100.0, -4.0 );
}
else{
L_restrict = 0;
R_restrict = 0;
}
float Lpercent = ( 100.0 - L_restrict ) / 100.00 ;
float Rpercent = ( 100.0 - R_restrict ) / 100.00 ;
L_MOTOR->setSpeed( velocity * Lpercent );
R_MOTOR->setSpeed( velocity * Rpercent );
return true;
}
return false;
}
bool isMoving = false;
bool buttonMode(){
static unsigned long lastPress = 0;
// Buttons
if (packetbuffer[1] == 'B') {
uint8_t buttnum = packetbuffer[2] - '0';
boolean pressed = packetbuffer[3] - '0';
// Serial.println(buttnum);
Serial.println(isMoving);
if (pressed) {
isMoving = true;
if(buttnum == 5){
L_MOTOR->run(FORWARD);
R_MOTOR->run(FORWARD);
}
if(buttnum == 6){
L_MOTOR->run(BACKWARD);
R_MOTOR->run(BACKWARD);
}
if(buttnum == 7){
L_MOTOR->run(RELEASE);
R_MOTOR->run(FORWARD);
}
if(buttnum == 8){
L_MOTOR->run(FORWARD);
R_MOTOR->run(RELEASE);
}
lastPress = millis();
L_MOTOR->setSpeed(255);
R_MOTOR->setSpeed(255);
}
else {
isMoving = false;
L_MOTOR->run(RELEASE);
R_MOTOR->run(RELEASE);
}
return true;
}
return false;
}
void BLEsetup(){
Serial.print(F("Initialising the Bluefruit LE module: "));
if ( !ble.begin(VERBOSE_MODE) )
{
error(F("Couldn't find Bluefruit, make sure it's in CoMmanD mode & check wiring?"));
}
Serial.println( F("OK!") );
/* Perform a factory reset to make sure everything is in a known state */
Serial.println(F("Performing a factory reset: "));
if (! ble.factoryReset() ){
error(F("Couldn't factory reset"));
}
//Convert the name change command to a char array
BROADCAST_CMD.toCharArray(buf, 60);
//Change the broadcast device name here!
if(ble.sendCommandCheckOK(buf)){
Serial.println("name changed");
}
delay(250);
//reset to take effect
if(ble.sendCommandCheckOK("ATZ")){
Serial.println("resetting");
}
delay(250);
//Confirm name change
ble.sendCommandCheckOK("AT+GAPDEVNAME");
/* Disable command echo from Bluefruit */
ble.echo(false);
Serial.println("Requesting Bluefruit info:");
/* Print Bluefruit information */
ble.info();
Serial.println(F("Please use Adafruit Bluefruit LE app to connect in Controller mode"));
Serial.println(F("Then activate/use the sensors, color picker, game controller, etc!"));
Serial.println();
ble.verbose(false); // debug info is a little annoying after this point!
/* Wait for connection */
while (! ble.isConnected()) {
delay(500);
}
Serial.println(F("*****************"));
// Set Bluefruit to DATA mode
Serial.println( F("Switching to DATA mode!") );
ble.setMode(BLUEFRUIT_MODE_DATA);
Serial.println(F("*****************"));
}
//Logarithmic mapping function from http://playground.arduino.cc/Main/Fscale
float fscale( float inputValue, float originalMin, float originalMax, float newBegin, float newEnd, float curve){
float OriginalRange = 0;
float NewRange = 0;
float zeroRefCurVal = 0;
float normalizedCurVal = 0;
float rangedValue = 0;
boolean invFlag = 0;
// condition curve parameter
// limit range
if (curve > 10) curve = 10;
if (curve < -10) curve = -10;
curve = (curve * -.1) ; // - invert and scale - this seems more intuitive - postive numbers give more weight to high end on output
curve = pow(10, curve); // convert linear scale into lograthimic exponent for other pow function
/*
Serial.println(curve * 100, DEC); // multply by 100 to preserve resolution
Serial.println();
*/
// Check for out of range inputValues
if (inputValue < originalMin) {
inputValue = originalMin;
}
if (inputValue > originalMax) {
inputValue = originalMax;
}
// Zero Refference the values
OriginalRange = originalMax - originalMin;
if (newEnd > newBegin){
NewRange = newEnd - newBegin;
}
else
{
NewRange = newBegin - newEnd;
invFlag = 1;
}
zeroRefCurVal = inputValue - originalMin;
normalizedCurVal = zeroRefCurVal / OriginalRange; // normalize to 0 - 1 float
/*
Serial.print(OriginalRange, DEC);
Serial.print(" ");
Serial.print(NewRange, DEC);
Serial.print(" ");
Serial.println(zeroRefCurVal, DEC);
Serial.println();
*/
// Check for originalMin > originalMax - the math for all other cases i.e. negative numbers seems to work out fine
if (originalMin > originalMax ) {
return 0;
}
if (invFlag == 0){
rangedValue = (pow(normalizedCurVal, curve) * NewRange) + newBegin;
}
else // invert the ranges
{
rangedValue = newBegin - (pow(normalizedCurVal, curve) * NewRange);
}
return rangedValue;
}
void loop(void)
{
count++;
if(count>= limit)
{
uint8_t i;
int solar1 = analogRead(A1);
int solar2 = analogRead(A2);
float voltage1 = (solar1 * (5.0/1023.0));
float voltage3 = (solar2 * (5.0/1023.0));
int wind = analogRead(A0);
float voltage2 = wind * (5.0/1023.0);
ble.print("Solar Voltage: ");
ble.print(voltage1);
ble.print(", ");
ble.println(voltage3);
ble.print("Wind Turbine Voltage: ");
ble.println(voltage2);
count = 1;
}
// read new packet data
uint8_t len = readPacket(&ble, BLE_READPACKET_TIMEOUT);
// if (len == 0) return;
// Read from Accelerometer input
if( accelMode() ) {
lastAccelPacket = millis();
modeToggle = true;
return;
}
// Stop motors if accelerometer data is turned off (100ms timeout)
if( millis() - lastAccelPacket > 100 & modeToggle) {
L_MOTOR->run(RELEASE);
R_MOTOR->run(RELEASE);
modeToggle = false;
return;
}
//if no accelerometer, use control pad
if( !modeToggle ) buttonMode();
}Below is the Bluetooth configuration code, the second file in the code called “BluefruitConfig.h”
// COMMON SETTINGS // ---------------------------------------------------------------------------------------------- // These settings are used in both SW UART, HW UART and SPI mode // ---------------------------------------------------------------------------------------------- #define BUFSIZE 128 // Size of the read buffer for incoming data #define VERBOSE_MODE true // If set to 'true' enables debug output #define BLE_READPACKET_TIMEOUT 500 // Timeout in ms waiting to read a response // SOFTWARE UART SETTINGS // ---------------------------------------------------------------------------------------------- // The following macros declare the pins that will be used for 'SW' serial. // You should use this option if you are connecting the UART Friend to an UNO // ---------------------------------------------------------------------------------------------- #define BLUEFRUIT_SWUART_RXD_PIN 9 // Required for software serial! #define BLUEFRUIT_SWUART_TXD_PIN 10 // Required for software serial! #define BLUEFRUIT_UART_CTS_PIN 11 // Required for software serial! #define BLUEFRUIT_UART_RTS_PIN -1 // Optional, set to -1 if unused // HARDWARE UART SETTINGS // ---------------------------------------------------------------------------------------------- // The following macros declare the HW serial port you are using. Uncomment // this line if you are connecting the BLE to Leonardo/Micro or Flora // ---------------------------------------------------------------------------------------------- #ifdef Serial1 // this makes it not complain on compilation if there's no Serial1 #define BLUEFRUIT_HWSERIAL_NAME Serial1 #endif // SHARED UART SETTINGS // ---------------------------------------------------------------------------------------------- // The following sets the optional Mode pin, its recommended but not required // ---------------------------------------------------------------------------------------------- #define BLUEFRUIT_UART_MODE_PIN 12 // Set to -1 if unused // SHARED SPI SETTINGS // ---------------------------------------------------------------------------------------------- // The following macros declare the pins to use for HW and SW SPI communication. // SCK, MISO and MOSI should be connected to the HW SPI pins on the Uno when // using HW SPI. This should be used with nRF51822 based Bluefruit LE modules // that use SPI (Bluefruit LE SPI Friend). // ---------------------------------------------------------------------------------------------- #define BLUEFRUIT_SPI_CS 8 #define BLUEFRUIT_SPI_IRQ 7 #define BLUEFRUIT_SPI_RST 4 // Optional but recommended, set to -1 if unused // SOFTWARE SPI SETTINGS // ---------------------------------------------------------------------------------------------- // The following macros declare the pins to use for SW SPI communication. // This should be used with nRF51822 based Bluefruit LE modules that use SPI // (Bluefruit LE SPI Friend). // ---------------------------------------------------------------------------------------------- #define BLUEFRUIT_SPI_SCK 13 #define BLUEFRUIT_SPI_MISO 12 #define BLUEFRUIT_SPI_MOSI 11
Below is the third file for the Arduino code, called “packetParser.cpp”
#include <string.h>
#include <Arduino.h>
#include <SPI.h>
#include <SoftwareSerial.h>
#include "Adafruit_BLE.h"
#include "Adafruit_BluefruitLE_SPI.h"
#include "Adafruit_BluefruitLE_UART.h"
#define PACKET_ACC_LEN (15)
#define PACKET_GYRO_LEN (15)
#define PACKET_MAG_LEN (15)
#define PACKET_QUAT_LEN (19)
#define PACKET_BUTTON_LEN (5)
#define PACKET_COLOR_LEN (6)
#define PACKET_LOCATION_LEN (15)
// READ_BUFSIZE Size of the read buffer for incoming packets
#define READ_BUFSIZE (20)
/* Buffer to hold incoming characters */
uint8_t packetbuffer[READ_BUFSIZE+1];
/**************************************************************************/
/*!
@brief Casts the four bytes at the specified address to a float
*/
/**************************************************************************/
float parsefloat(uint8_t *buffer)
{
float f = ((float *)buffer)[0];
return f;
}
/**************************************************************************/
/*!
@brief Prints a hexadecimal value in plain characters
@param data Pointer to the byte data
@param numBytes Data length in bytes
*/
/**************************************************************************/
void printHex(const uint8_t * data, const uint32_t numBytes)
{
uint32_t szPos;
for (szPos=0; szPos < numBytes; szPos++)
{
Serial.print(F("0x"));
// Append leading 0 for small values
if (data[szPos] <= 0xF)
{
Serial.print(F("0"));
Serial.print(data[szPos] & 0xf, HEX);
}
else
{
Serial.print(data[szPos] & 0xff, HEX);
}
// Add a trailing space if appropriate
if ((numBytes > 1) && (szPos != numBytes - 1))
{
Serial.print(F(" "));
}
}
Serial.println();
}
/**************************************************************************/
/*!
@brief Waits for incoming data and parses it
*/
/**************************************************************************/
uint8_t readPacket(Adafruit_BLE *ble, uint16_t timeout)
{
uint16_t origtimeout = timeout, replyidx = 0;
memset(packetbuffer, 0, READ_BUFSIZE);
while (timeout--) {
if (replyidx >= 20) break;
if ((packetbuffer[1] == 'A') && (replyidx == PACKET_ACC_LEN))
break;
if ((packetbuffer[1] == 'G') && (replyidx == PACKET_GYRO_LEN))
break;
if ((packetbuffer[1] == 'M') && (replyidx == PACKET_MAG_LEN))
break;
if ((packetbuffer[1] == 'Q') && (replyidx == PACKET_QUAT_LEN))
break;
if ((packetbuffer[1] == 'B') && (replyidx == PACKET_BUTTON_LEN))
break;
if ((packetbuffer[1] == 'C') && (replyidx == PACKET_COLOR_LEN))
break;
if ((packetbuffer[1] == 'L') && (replyidx == PACKET_LOCATION_LEN))
break;
while (ble->available()) {
char c = ble->read();
if (c == '!') {
replyidx = 0;
}
packetbuffer[replyidx] = c;
replyidx++;
timeout = origtimeout;
}
if (timeout == 0) break;
delay(1);
}
packetbuffer[replyidx] = 0; // null term
if (!replyidx) // no data or timeout
return 0;
if (packetbuffer[0] != '!') // doesn't start with '!' packet beginning
return 0;
// check checksum!
uint8_t xsum = 0;
uint8_t checksum = packetbuffer[replyidx-1];
for (uint8_t i=0; i<replyidx-1; i++) {
xsum += packetbuffer[i];
}
xsum = ~xsum;
// Throw an error message if the checksum's don't match
if (xsum != checksum)
{
Serial.print("Checksum mismatch in packet : ");
printHex(packetbuffer, replyidx+1);
return 0;
}
// checksum passed!
return replyidx;
}