Objective:

Treasure Detection:

• To implement treasure detection, we first built a non-inverting amplifier for the phototransistor.
• To do this we used a LM-358AN Op Amp IC
• The schematic for this circuit is pictured below
  
• We first tested the amplifier with the function generator. The results can be seen below
  
• When we first tested the circuit using the phototransistor we forgot to include the pull down resistor so it did not work properly
• Once we added the resistor, we were able to amplify the signal
• The FFT data for this is pictured below
  

• 7kHz From 1.5" Away:

  

• 12kHz From 2" Away:

  

• 17kHz From 2" Away:

  
• The amplifier gave us a gain of about 4
• Below is the code we used to identify the frequencies
• We checked the bins and compared their averages so if there was a maximum, the program would identify the frequency

               while(1) {     // reduces jitter
                  cli();        // UDRE interrupt slows this way down on arduino1.0
                  for (int i = 0 ; i < 512 ; i += 2) {      // save 256 samples
                    while(!(ADCSRA & 0x10)); // wait for adc to be ready
                    ADCSRA = 0xf5;        // restart adc
                    byte m = ADCL;        // fetch adc data
                    byte j = ADCH;
                    int k = (j << 8) | m; // form into an int
                    k -= 0x0200;          // form into a signed int
                    k <<= 6;              // form into a 16b signed int
                    fft_input[i] = k;     // put real data into even bins
                    fft_input[i+1] = 0;   // set odd bins to 0
                  }
                  fft_window();           // window the data for better frequency response
                  fft_reorder();          // reorder the data before doing the fft
                  fft_run();              // process the data in the fft
                  fft_mag_log();          // take the output of the fft
                  sei();
                  /*
                  7kHz: [44,49]
                  12kHz: [78,82]
                  17kHz: [112,116]
                  */
                  int max_7k = max_in_range(44,49);
                  int max_12k = max_in_range(78,82);
                  int max_17k = max_in_range(112,116);
                  int RATIO_THRESH = 2.5;
  
                  if (max_7k/30 > RATIO_THRESH) {
                    Serial.println("7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k 7k");
                  }
                  else if (max_12k/30 > RATIO_THRESH) {
                    Serial.println("12k   12k   12k   12k   12k   12k   12k   12k   12k");
                  }
                  else if (max_17k/30 > RATIO_THRESH) {
                    Serial.println("17k     17k     17k     17k     17k     17k     17k");
                  }
                  else {
                    Serial.println("No Signal");
                  }   
                }
              

• The final circuit with amplifier was able to detect each frequency from around 2 inches away

Wall Detection:

          void loop() {

            // go straight when threshold has not been reached
            while (analogRead(wallRightSide) <= threshSide) {
              int lRead = analogRead(leftLine);
              int rRead = analogRead(rightLine);
              int lwRead = analogRead(leftWide);
              int rwRead = analogRead(rightWide);

              if(lRead<=thresh && rRead<=thresh){     // stop
                left.write(90);
                right.write(90);
              }
              else{
                if(lRead<thresh){  // left side is out of line
                  left.write(170);
                  right.write(89);
                }
                else if(rRead<thresh){   // right side is out of line
                  left.write(91);
                  right.write(10);
                }
                else{     // go straight
                  left.write(100);
                  right.write(80);
                }
              }
            }

          //   else stop when wall is detected
            left.write(90);
            right.write(90);

          }
          

Final Robot of Milestone 2:

Update 10/28/17