This Vehicle is essentially the controlled vehicle: of the many possible paths its purpose is to follow the path of the Leading Vehicle. By itself, the Guided Vehicle has no sensors to detect the path, and must rely on staying behind the Leading Vehicle at a close distance in order follow it. For this purpose the Guided Vehicle was fitted with 2 Ultrasonic sensors, placed on the left and right of its bumper, as shown in figure 4.1 above.
Figure 4.1a shows the Guided Vehicle behind the Leading Vehicle when both Lgap and Rgap are in the range of 12cm and 15cm. When this scenario arises the Guided Vehicle is instructed to stop moving forward and wait until the Leading Vehicle moves forward once again.
• If the Lgap is more than 15cm and R gap is less than 12cm the Guided Vehicle is instructed to turn right, as seen in figure 4.1b.
• When Rgap is more than 15cm and L gap is less than 12cm the Guided Vehicle will do a left turn as shown in figure 4.1c.
Table 4.1 shows how the values of the sensors affect the motor control.
The algorithm for the Guided Vehicle Control is shown in Figure 4.2.
4.2 CONSTRUCTION OF THE GUIDED VEHICLE
• If the Lgap is more than 15cm and R gap is less than 12cm the Guided Vehicle is instructed to turn right, as seen in figure 4.1b.
• When Rgap is more than 15cm and L gap is less than 12cm the Guided Vehicle will do a left turn as shown in figure 4.1c.
Table 4.1 shows how the values of the sensors affect the motor control.
The algorithm for the Guided Vehicle Control is shown in Figure 4.2.
Figure 4.2: The Algorithm for the working of the Guided Vehicle
4.2 CONSTRUCTION OF THE GUIDED VEHICLE
• The chassis was constructed from the 5mm transparent acrylic sheet.
• The DC Motors were attached to the acrylic chassis with the supplied 16mm diameter nuts.
•The wheels were then fitted onto the shafts of each DC Motor.
• The DC Motors were attached to the acrylic chassis with the supplied 16mm diameter nuts.
•The wheels were then fitted onto the shafts of each DC Motor.
Figure 4.3 shows the electronic components and their interconnections.
•Pins labeled Vin, GND, GND, 5V, A0, A1, 0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 12 are Male Header connections that are to be directly plugged into the respective Female Headers of an Arduino UNO board. Similarly in the RF connection bay, the pins 5V, GND, 1, 0 are Female Headers on this board that can be directly attached to the respective male headers of RF receiver board.
•This modular design was opted for ease of addition/removal of the Arduino, L293D and RF receiver for easier troubleshooting.
4.3 STEPS IN SOLDERING THE COMPONENTS OF THE GUIDED VEHICLE
1. Wet the sponge in the soldering iron stand.
2. Allow the iron to come up to temperature.
3. Tin the tip of the iron by pressing the solder against it until it melts and covers the tip.
4. Wipe the tip on the wet sponge—this produces a satisfying sizzling sound, but also cleans off the excess solder. We should now have a nice bright silver tip.
5. Touch the iron to the place where you are going to solder to heat it; then after a short pause (a second or two), touch the solder to the point where the tip of the iron meets the thing we are soldering. The solder should flow like a liquid, neatly making a joint.
6. Remove the solder and the soldering iron, putting the iron back in its stand, being very careful that nothing moves in the few seconds that the solder will take to solidify. If something does move, then touch the iron to it again to reflow the solder; otherwise, we can get a bad connection called a dry joint. Above all, try not to heat sensitive (or expensive) components any longer than necessary, especially if they have short leads.
• Figure 4.4 shows the final circuit board.
• Decoupling capacitors (see page 52) have been added to filter out voltage spikes to the micro-controller and L293D IC and improve circuit lifespan.
• Diode 1N4001 has been added in forward bias between the switch and the arduino and L293D. This protects the circuit in the case of an accidental reverse bias battery connection.
• Screw terminal blocks are used to connect the motors to the circuit (shown as rings in the schematic figure 4.3).
• The male headers, between the terminal blocks, are used to connect
◦ and the battery
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| The breadboard view of the guided vehicle circuit board |