Technology Tutorials

In this lesson we show you the importance of building a parameterized model for your 3D graphics in Python using Visual Python. You can manage large scenes unless you are doing it with parameterized dimensions. The video above takes you through it step by step. Here is the code for the parameterized box and marble we developed in Lesson 3:

from vpython import *
from time import *
mRadius=.75
wallThickness=.1
roomWidth=10
roomDepth=5
roomHeight=10
floor=box(pos=vector(0,-roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)
ceiling=box(pos=vector(0,roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)
backWall=box(pos=vector(0,0,-roomDepth/2),size=vector(roomWidth,roomHeight,wallThickness), color=color.white)
leftWall=box(pos=vector(-roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)
rightWall=box(pos=vector(roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)
marble=sphere(radius=mRadius,color=color.red)
deltaX=.1
xPos=0
while True:
    rate(10)
    xPos=xPos+deltaX
    if (xPos>roomWidth/2 or xPos<-roomWidth/2):
        deltaX=deltaX*(-1)
    marble.pos=vector(xPos,0,0)

from vpython import *

from time import *

mRadius=.75

wallThickness=.1

roomWidth=10

roomDepth=5

roomHeight=10

floor=box(pos=vector(0,-roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)

ceiling=box(pos=vector(0,roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)

backWall=box(pos=vector(0,0,-roomDepth/2),size=vector(roomWidth,roomHeight,wallThickness), color=color.white)

leftWall=box(pos=vector(-roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)

rightWall=box(pos=vector(roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)

marble=sphere(radius=mRadius,color=color.red)

deltaX=.1

xPos=0

while True:

rate(10)

xPos=xPos+deltaX

if (xPos>roomWidth/2 or xPos<-roomWidth/2):

deltaX=deltaX*(-1)

marble.pos=vector(xPos,0,0)

In this lesson we explore using the HC-SR04 to detect obstacles, and then avoid collisions by stopping the car. This requires a more sophisticated control algorithm for the desired distance for the car to travel. Making it even more tricky, after the obstacle is removed, the car needs to resume its programmed mission. The video shows my solution to this problem

int Trig=A5;
int Echo=A4;

int ENA=5;
int ENB=6;
int IN1=7;
int IN2=8;
int IN3=9;
int IN4=11;
float d=1;
int degRot=90;
int left;
int right;
float v=1.2;
int rv;
char cmd;
void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(Trig,OUTPUT);
pinMode(Echo,INPUT);


pinMode(ENA,OUTPUT);
pinMode(ENB,OUTPUT);
pinMode(IN1,OUTPUT);
pinMode(IN2,OUTPUT);
pinMode(IN3,OUTPUT);
pinMode(IN4,OUTPUT);
digitalWrite(ENA,HIGH);
digitalWrite(ENB,HIGH);
}

void loop() {
int wv;
//v=1.2;
//d=1;
wv=(v-.35)/.0075;
left=wv;
right=wv;
setSpeed(left,right);
while (Serial.available()==0){
}
cmd=Serial.read();
if (cmd=='G'){
  Serial.println("Forward");
  forward(d,v);  
}
if (cmd=='B'){
  Serial.println("Backward");
  backward(d,v);  
}
if (cmd=='R'){
  Serial.println("Right");
  turnRight(degRot,wv);  
}
if (cmd=='L'){
  Serial.println("Left");
  turnLeft(degRot,wv);  
}
//If Command Was Pound, Set Distance
if (cmd=='d'){
  Serial.println("Set distance");
  delay(500);

  while (Serial.available()==0){
  }
cmd=Serial.read();

    if (cmd=='1'){
    Serial.println("Distance=1");
    d=1;
  }
    if (cmd=='2'){
    Serial.println("Distance=2");
    d=2;
  }
      if (cmd=='3'){
    Serial.println("Distance=3");
    d=3;
  }
      if (cmd=='4'){
    Serial.println("Distance=4");
    d=4;
  }
      if (cmd=='5'){
    Serial.println("Distance=5");
    d=5;
  }
      if (cmd=='6'){
    Serial.println("Distance=6");
    d=6;
  }
      if (cmd=='7'){
    Serial.println("Distance=7");
    d=7;
  }
      if (cmd=='8'){
    Serial.println("Distance=8");
    d=8;
  }
      if (cmd=='9'){
    Serial.println("Distance=9");
    d=9;
  }
}

//If Command Was star, Set Speed
if (cmd=='v'){
  Serial.println("Set speed");
  delay(500);
   while (Serial.available()==0){
    
  }
  delay(100);
  cmd=Serial.read();
    if (cmd=='1'){
    Serial.println("rv=1");
    rv=1;
  }
    if (cmd=='2'){
    Serial.println("rv=2");
    rv=2;
  }
      if (cmd=='3'){
    Serial.println("rv=3");
    rv=3;
  }
      if (cmd=='4'){
    Serial.println("rv=4");
    rv=4;
  }
      if (cmd=='5'){
    Serial.println("rv=5");
    rv=5;
  }
      if (cmd=='6'){
    Serial.println("rv=6");
    rv=6;
  }
      if (cmd=='7'){
    Serial.println("rv=7");
    rv=7;
  }
      if (cmd=='8'){
    Serial.println("rv=8");
    rv=8;
  }
      if (cmd=='9'){
    Serial.println("rv=9");
    rv=9;
  }
  v=(1.16/9.)*rv+1.1;




}
}
void setSpeed(int leftVal,int rightVal){
  analogWrite(ENA,leftVal);
  analogWrite(ENB,rightVal);
}
void forward(float d, float v){
float tTarget;
float dObs;
int tOn;
int tStart;
bool carBlocked=false;
int tStopped=0;
int t1;
int t2;
tStart=millis();
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
tTarget=d/v*1000;
tOn=millis()-tStart-tStopped;
while (tOn<=tTarget){
tOn=millis()-tStart-tStopped;
dObs=measDist();
t1=millis();
while(dObs<=12){
  stopCar();
  dObs=measDist();
  carBlocked=true;
}
t2=millis();
if (carBlocked==true){
  tStopped=tStopped+(t2-t1);
  carBlocked=false;
  digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
}
}
stopCar();
}
void backward(float d, float v){
float t;
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
t=d/v*1000;
delay(t);
stopCar();
}
void turnRight(int deg, int wv){
  float t;
stopCar();
delay(100);
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
t=(deg+6)/136.29*1000.;
delay(t);
stopCar();
analogWrite(ENA,wv);
analogWrite(ENB,wv);
}
void turnLeft(int deg, int wv){
float t;
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
t=(deg+6)/136.29*1000.;
delay(t);
stopCar();
analogWrite(ENA,wv);
analogWrite(ENB,wv);
}
void stopCar(){
digitalWrite(IN1,LOW);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,LOW);
}

void calF(){
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
delay(5000);
stopCar();
}
void calB(){
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
delay(5000);
stopCar();
}
void calR(int wv){
stopCar();
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
delay(3000);
analogWrite(ENA,wv);
analogWrite(ENB,wv);
stopCar();
}
void calL(int wv){
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
delay(5000);
analogWrite(ENA,wv);
analogWrite(ENB,wv);
stopCar();
}

unsigned int pingTime(){
  unsigned int pingTravelTime;
  digitalWrite(Trig, LOW);   
  delayMicroseconds(2);
  digitalWrite(Trig, HIGH);  
  delayMicroseconds(20);
  digitalWrite(Trig, LOW);   
  pingTravelTime = pulseIn(Echo, HIGH);        
  return pingTravelTime; 
}
float measDist(){
 unsigned int pingTravelTime;
  float Dist;
  pingTravelTime=pingTime();
  Dist=(pingTravelTime*761.*5280.*12.)/(1000000.*3600.);
  Dist=Dist/2;
  return Dist;
}

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int Trig=A5;

int Echo=A4;

int ENA=5;

int ENB=6;

int IN1=7;

int IN2=8;

int IN3=9;

int IN4=11;

float d=1;

int degRot=90;

int left;

int right;

float v=1.2;

int rv;

char cmd;

void setup() {

// put your setup code here, to run once:

Serial.begin(9600);

pinMode(Trig,OUTPUT);

pinMode(Echo,INPUT);

pinMode(ENA,OUTPUT);

pinMode(ENB,OUTPUT);

pinMode(IN1,OUTPUT);

pinMode(IN2,OUTPUT);

pinMode(IN3,OUTPUT);

pinMode(IN4,OUTPUT);

digitalWrite(ENA,HIGH);

digitalWrite(ENB,HIGH);

}

void loop() {

int wv;

//v=1.2;

//d=1;

wv=(v-.35)/.0075;

left=wv;

right=wv;

setSpeed(left,right);

while (Serial.available()==0){

}

cmd=Serial.read();

if (cmd=='G'){

Serial.println("Forward");

forward(d,v);

}

if (cmd=='B'){

Serial.println("Backward");

backward(d,v);

}

if (cmd=='R'){

Serial.println("Right");

turnRight(degRot,wv);

}

if (cmd=='L'){

Serial.println("Left");

turnLeft(degRot,wv);

}

//If Command Was Pound, Set Distance

if (cmd=='d'){

Serial.println("Set distance");

delay(500);

while (Serial.available()==0){

}

cmd=Serial.read();

if (cmd=='1'){

Serial.println("Distance=1");

d=1;

}

if (cmd=='2'){

Serial.println("Distance=2");

d=2;

}

if (cmd=='3'){

Serial.println("Distance=3");

d=3;

}

if (cmd=='4'){

Serial.println("Distance=4");

d=4;

}

if (cmd=='5'){

Serial.println("Distance=5");

d=5;

}

if (cmd=='6'){

Serial.println("Distance=6");

d=6;

}

if (cmd=='7'){

Serial.println("Distance=7");

d=7;

}

if (cmd=='8'){

Serial.println("Distance=8");

d=8;

}

if (cmd=='9'){

Serial.println("Distance=9");

d=9;

}

//If Command Was star, Set Speed

if (cmd=='v'){

Serial.println("Set speed");

delay(500);

while (Serial.available()==0){

}

delay(100);

cmd=Serial.read();

if (cmd=='1'){

Serial.println("rv=1");

rv=1;

}

if (cmd=='2'){

Serial.println("rv=2");

rv=2;

}

if (cmd=='3'){

Serial.println("rv=3");

rv=3;

}

if (cmd=='4'){

Serial.println("rv=4");

rv=4;

}

if (cmd=='5'){

Serial.println("rv=5");

rv=5;

}

if (cmd=='6'){

Serial.println("rv=6");

rv=6;

}

if (cmd=='7'){

Serial.println("rv=7");

rv=7;

}

if (cmd=='8'){

Serial.println("rv=8");

rv=8;

}

if (cmd=='9'){

Serial.println("rv=9");

rv=9;

}

v=(1.16/9.)*rv+1.1;

}

void setSpeed(int leftVal,int rightVal){

analogWrite(ENA,leftVal);

analogWrite(ENB,rightVal);

}

void forward(float d, float v){

float tTarget;

float dObs;

int tOn;

int tStart;

bool carBlocked=false;

int tStopped=0;

int t1;

int t2;

tStart=millis();

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

tTarget=d/v*1000;

tOn=millis()-tStart-tStopped;

while (tOn<=tTarget){

tOn=millis()-tStart-tStopped;

dObs=measDist();

t1=millis();

while(dObs<=12){

stopCar();

dObs=measDist();

carBlocked=true;

}

t2=millis();

if (carBlocked==true){

tStopped=tStopped+(t2-t1);

carBlocked=false;

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

}

stopCar();

}

void backward(float d, float v){

float t;

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

t=d/v*1000;

delay(t);

stopCar();

}

void turnRight(int deg, int wv){

float t;

stopCar();

delay(100);

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

t=(deg+6)/136.29*1000.;

delay(t);

stopCar();

analogWrite(ENA,wv);

analogWrite(ENB,wv);

}

void turnLeft(int deg, int wv){

float t;

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

t=(deg+6)/136.29*1000.;

delay(t);

stopCar();

analogWrite(ENA,wv);

analogWrite(ENB,wv);

}

void stopCar(){

digitalWrite(IN1,LOW);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,LOW);

}

void calF(){

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

delay(5000);

stopCar();

}

void calB(){

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

delay(5000);

stopCar();

}

void calR(int wv){

stopCar();

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

delay(3000);

analogWrite(ENA,wv);

analogWrite(ENB,wv);

stopCar();

}

void calL(int wv){

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

delay(5000);

analogWrite(ENA,wv);

analogWrite(ENB,wv);

stopCar();

}

unsigned int pingTime(){

unsigned int pingTravelTime;

digitalWrite(Trig, LOW);

delayMicroseconds(2);

digitalWrite(Trig, HIGH);

delayMicroseconds(20);

digitalWrite(Trig, LOW);

pingTravelTime = pulseIn(Echo, HIGH);

return pingTravelTime;

}

float measDist(){

unsigned int pingTravelTime;

float Dist;

pingTravelTime=pingTime();

Dist=(pingTravelTime*761.*5280.*12.)/(1000000.*3600.);

Dist=Dist/2;

return Dist;

}

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Python 3D Graphics LESSON 3: Parameterizing your 3D Model

Launch a Windows WEB Camera in Ten Lines of Code with OpenCV

Robotics Training LESSON 18: Obstacle Detection and Collision Avoidance

Making The World a Better Place One High Tech Project at a Time. Enjoy!