/ / INTRODUCTION

This bot uses bump sensors to navigate around objects.

The bump sensor works by connecting two wires together when the bot bumps into something. These kind of trigger sensors are used for object detection.

Parts

• Arduino
• Makerbotted base
• Makerbotted servo holders
• Makerbotted caster wheel
• Makerbotted battery clip
• Makerbotted wheels
• Protoshield
• 2 continuous rotation servo motors
• 3 SPST switches
• nuts and bolts
• 1/2 inch chrome ball
• 12ft copper bare wire 18awg
• 9 Volt battery
• 2 LEDs
• 5k potentiometer
• 2 rubber bands
• 2 SPST power switches

Bump Sensors

The robot wanders around autonomously until it bumps into something. You need to place the sensors in strategic locations so that the bot always detects the obstacles. It is important also that there is enough time between sensing and reacting.

Antennae

The front antennae sensors are wires connected to coiled wires which are connected to the Arduino digital pins and and a bolt connected to GND. The bolt is inside the coil so when the wire connected to the coil hits something, the coil makes an electrical connection with the bolt and closes the circuit. When the sensor is triggered, the bot stops and reverses direction, then stops and turns and proceeds in a new direction.

1. Take 4-6 feet of 18 awg wire. Wrap the wire around a 3/4 inch cylinder
   
   

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2. Repeat for the second antennae
   
   

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3. Unwrap 6 inches from the coil. This will be the antennae.
   
   

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4. Solder a wire to the bottom of the coil and attach the wire to the Arduino digital pins
   
   

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5. Solder a wire to the bolt and connect that wire to GND.
   
   

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6. Thread the bolt through the base of the bot
   
   

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7. Hot glue the base of the coil to the bot base. Don't get glue on the spirals above the bottom spiral.
   
   

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SPST Switches

The SPST switches act the same way the antennae switches do. When contact is made, the circuit is closed.

If you have a minimum of two sensors on the front and three on the back, the bot should be able to navigate.

Attach the three switches to bumpers on the back of the bot. And connect the leads to the Arduino digital pins and GND.

SPST switches

One is used for power:
Cut the red wire of the power supply. Solder each lead to a lead of the toggle switch.

One is used to toggle the mode of the robot. Connect the two leads of the switch to Arduino digital 4 and to GND.

The Code

Click to copy code// Bug-bot v1.2 // (2) Servo motors (modified for continuous rotation) with tank-steering setup (pins 9 and 10). // (5) bump sensors total - 2 in front (pins 2 and 3) and 3 in rear (pins 5, 6, 7). // All sensors are normally HIGH (1) using arduino internal pull-up resistors. // Sensors are brought LOW (0) by contacting the switch connected to GND. // Either set of sensors can be used (front or back), by changing Mode Switch on pin 4. // Pin 4 (HIGH or LOW) changes the bots default direction and sensors. // // include the Servo.h Arduino library #include <Servo.h> // create instances for each servo using the Servo.h library // for more information, see: Servo servo_L; Servo servo_R; ///////////// Variables used for testing (you can change these) // use to determine direction of bot and which sensors to use. int mode_pin = 4; // connect the mode switch to digital pin 4 int antennae_L = 3; // connect left antennae sensor to digital pin 3 int antennae_R = 2; // connect right antennae sensor to digital pin 2 int bumper_R = 5; // connect right bump sensor to Analog pin 0, which is pin 14 when used as a digital pin int bumper_C = 6; // connect center bump sensor to Analog pin 1 (digital pin 15) int bumper_L = 7; // connect left bump sensor to Analog pin 2 (digital pin 16) // Value to change servo stopping point pulse - use Code 7-2 to determine the specific pulse for each motor int servo_R_stop = 89; // set the Neutral position for Right Servo - change as needed int servo_L_stop = 89; // set the Neutral position for Left Servo - change as needed // integers to use for updating Servo motors // change these values to change the various motor actions int stop_time = 1000; // stop for 1000 millliseconds = 1 second int backup_time = 700; // backup for 700 milliseconds = .7 seconds int turn_time = 300; // turn (either direction) for 300 milliseconds = .3 seconds ////////////////////////// End of variables used for testing // value names used to hold timing variables. unsigned long timer_startTick; // value names used to hold antennae states int antennae_R_val; int antennae_L_val; // value names used to hold bumper states int bumper_R_val; int bumper_C_val; int bumper_L_val; // Set the forward and reverse speed values for the Right Servo based on the Neutral position int servo_R_forward = servo_R_stop + 50; int servo_R_reverse = servo_R_stop - 50; // Set the forward and reverse speed values for the Left Servo based on the Neutral position int servo_L_forward = servo_L_stop - 50; int servo_L_reverse = servo_L_stop + 50; // end of variables // Begin Setup void setup(){ Serial.begin(9600); // start Serial connection at 9600 bps servo_L.attach(9); // attach servo_L to pin 9 using the Servo.h library servo_R.attach(10); // attach servo_R to pin 10 using the Servo.h library pinMode(mode_pin, INPUT); // declare input digitalWrite(mode_pin, HIGH); // enable pull-up resistor pinMode(antennae_R, INPUT); // declare input digitalWrite(antennae_R, HIGH); // enable pull-up resistor pinMode(antennae_L, INPUT); // declare input digitalWrite(antennae_L, HIGH); // enable pull-up resistor pinMode(bumper_R, INPUT); // declare input digitalWrite(bumper_R, HIGH); // enable pull-up resistor pinMode(bumper_C, INPUT); // declare input digitalWrite(bumper_C, HIGH); // enable pull-up resistor pinMode(bumper_L, INPUT); // declare input digitalWrite(bumper_L, HIGH); // enable pull-up resistor } // End Setup // Begin Loop void loop(){ //////////////////////////////////////////////////////// // if the switch_pin is LOW, use the Antennae sensors //////////////////////////////////////////////////////// if (!digitalRead(mode_pin) ){ antennae_R_val = digitalRead(antennae_R); // read Right antennae antennae_L_val = digitalRead(antennae_L); // read Left antennae // Use Antennae sensors // check to see if either antennae sensor is connected to GND (it is being touched). if (antennae_R_val == 0 || antennae_L_val == 0){ // now check to see if only the Left antennae was touched if (!antennae_R_val && antennae_L_val){ // if so, print the word "Left" Serial.println("Left"); // reset timer timer_startTick = millis(); // Stop motors stop_motors(); // back up a bit backup_motors(); // turn Right for a bit turn_right(); } // otherwise, if the Right sensor was touched and the Left was not, else if (antennae_R_val && !antennae_L_val){ // print the word "Right" Serial.println("Right"); // reset timer timer_startTick = millis(); // Stop motors stop_motors(); // back up a bit backup_motors(); // turn Left for a bit turn_left(); } else { // otherwise, both antennae sensors were touched // print the word "Both" Serial.println("Both"); // reset timer timer_startTick = millis(); // Stop motors stop_motors(); // back up a bit backup_motors(); // turn either direction turn_left(); } } else { // otherwise no sensors were touched, so go Forward! forward_motors(); } // print the states of each antennae Serial.print("Right sensor"); Serial.print(antennae_R_val); Serial.print(" "); Serial.print("Left sensor"); Serial.print(antennae_L_val); Serial.println(" "); // End Antennae sensors } /////////////////////////////////////////////////////////// // Else, if the switch_pin is HIGH, use the Bumper sensors /////////////////////////////////////////////////////////// else{ // read the bumper sensors bumper_R_val = digitalRead(bumper_R); bumper_C_val = digitalRead(bumper_C); bumper_L_val = digitalRead(bumper_L); // Use Bumper sensors // check to see if the right bumper was touched if (!bumper_R_val){ // if so, print the word "Right" Serial.println("Right"); // reset timer timer_startTick = millis(); // Stop motors stop_motors(); // back up a bit ahead_motors(); // turn Left turn_left(); } // check to see if the left bumper was touched else if (!bumper_L_val){ // if so, print the word "Left" Serial.println("Left"); // reset timer timer_startTick = millis(); // Stop motors stop_motors(); // back up a bit ahead_motors(); // turn Right turn_right(); } // check to see if the center bumper was touched else if (!bumper_C_val){ // if so, print the word "Center" Serial.println("Center"); // reset timer timer_startTick = millis(); // Stop motors stop_motors(); // back up a bit ahead_motors(); // turn Left turn_left(); } else{ // otherwise no sensors were touched, so go Forward (which is actually Reverse when the direction is switched)! reverse_motors(); } // print the states of each bumper Serial.print("Right Bumper: "); Serial.print(bumper_R_val); Serial.print(" "); Serial.print("Left Bumper: "); Serial.print(bumper_R_val); Serial.print(" "); Serial.print("Center Bumper: "); Serial.print(bumper_L_val); Serial.println(" "); } // End Bumper sensors } ///////////////////// End Loop ///////////////////// // Beginning motor control functions void stop_motors(){ // stop motors for the amount of time defined in the "stop_time" variable while(millis() < timer_startTick + stop_time){ servo_L.write(servo_L_stop); servo_R.write(servo_R_stop); } timer_startTick = millis(); // reset timer variable } void backup_motors(){ // backup for the amount of time defined in the "backup_time" variable while(millis() < timer_startTick + backup_time){ servo_L.write(servo_L_reverse); servo_R.write(servo_R_reverse); } timer_startTick = millis(); // reset timer variable } void ahead_motors(){ // go forward for the amount of time defined in the "backup_time" variable while(millis() < timer_startTick + backup_time){ servo_L.write(servo_L_forward); servo_R.write(servo_R_forward); } timer_startTick = millis(); // reset timer variable } void turn_right(){ // turn right for the amount of time defined in the "turn_time" variable while(millis() < timer_startTick + turn_time){ servo_L.write(servo_L_forward); servo_R.write(servo_R_reverse); } } void turn_left(){ // turn left for the amount of time defined in the "turn_time" variable while(millis() < timer_startTick + turn_time){ servo_L.write(servo_L_reverse); servo_R.write(servo_R_forward); } } void reverse_motors(){ // go reverse indefinitely servo_L.write(servo_L_reverse); servo_R.write(servo_R_reverse); } void forward_motors(){ // go forward indefinitely servo_L.write(servo_L_forward); servo_R.write(servo_R_forward); } // End motor control functions // End Code