RoboCar Making Tutorials - PART:1 || 6 Robots || Obstacle Avoiding, Light Controlled, Line Following, Etc...

Hello Everyone,

GOOD DAY !!! Recently I made some simple Robocar projects for my friend's son. For that I made a report in step by step and also made a video tutorial for all the robo ideas. Total I think around 6 different Robot ideas. So I thought it is better to share all the information with you guys also. Because information is not a thing to hide. So you can use it. If you are facing any issues, you can ask me without any hesitation. I am dividing my Robocar tutorial in four parts, Here it is first part. Let's start....

Limit Switch SPDT three 3 pin 1A/125V or 2A/125V : 6 Nos

Limit Switch SPDT three 3 pin 5A/125V : 4 Nos

Female Spade Crimp Connector Size: Suitable for above limit switch lever (for both) :4 Nos each

170 point mini Breadboard : 1 Nos

3x1.5V AA Battery Box Holder : 1 Nos

IR Proximity Sensor Board : 3 Nos

LM293D Motor Driver Board : 2 Nos

Male-Male breadboard jumper wire : 30 Nos

Male-Female breadboard jumper wire : 10 Nos

Nuts & Bolts

M 2.5 x 25mm (diameter 2.5mm*length 25mm) : 8 Nos

M 2.5 x 10mm (diameter 2.5mm*length 10mm) : 10 Nos

PCB Single Stranded Wire : 4 Meter

Single Stranded Wire 1 mm : 1 Meter

Heat Shrink Tube – 2.5mm : 1 Nos

Double Side Foam Tape : 1 Nos

1.5V AA Cell : 10 Nos

9V Battery and battery connector : 2 Nos

3 mm LED RED : 10 Nos

3 mm LED White : 10 Nos

Resistor 1KΩ ¼ W : 10 Nos

Resistor 220Ω ¼ W : 10 Nos

Resistor 47KΩ ¼ W : 4 Nos

Resistor 100KΩ ¼ W : 4 Nos

Capacitor 1 MFD 25V : 2 Nos

Capacitor 100 MFD 25V : 2 Nos

Diode 1N4007 : 4 Nos

IC NE555 : 4 Nos

Transistor BC547 : 5 Nos

Relay 5V SPDT : 2 Nos

LDR Sensor : 3 No

1.1. Battery

Everytime we are wrongly calling the 1.5V cell as a battery. But in reality it is not a battery it is a single “CELL” only. Basically battery is a collection of cells. In this KIT there are 2 battery holders, which holdes the battery and it give the output voltage. Here this battery producing 3V from series connection of two 1.5V cells. The image represents the 3V battery arrangement. We will get the output voltage from the 2 wires (Red and Black). Every battery have polarity, here the Red wire is the positive terminal and the Black one is the negative terminal (this colour coding is the common one). Note: Avoid direct connection between red and black wires (short circuit) because it will destroy the battery charge. So when you are not using the battery, disconnect the 1.5V cells from the battery holder.

1.2. DC Motor

Motor is a device which convert the elctric energy into mechanical energy (rotational motion). Here it is a geared motor. The gear is used here to decrease the rotational speed of the motor (rpm) and thus increase the torque. It is a 2 terminal device, the 2 terminal are used to give the DC electric energy into the motor for its operation. Every motor have a voltage and current rating at which it will work perfectly without any problem. We can connect it into the 3V battery. When the polarity of the input DC changes, it will change the rotational direction (we will see it in future chapters).

1.3. LED and Resistor

LED (Light Emitting Diode) is a device which convert electrical energy into light eneregy. Each LED have their on voltage and current ratings, if these are higher than the rated value then it will destroy the LED permanently. So we use resistor to limit the current flow through the LED (this current flow produce a voltage drop across the resistor thus LED voltage will also decrease) to protect it from damage. The value of the resistor is determining the amount of current flow. The value written on the resistror surface using colour coded rings. In the image it is a 1 Kilo Ohm resistor. The LED is a polarized device. It only works in one polarity.

Note: Never connect LED directly to the battery. Connect it to the battery in series with a 1 K resistor. For the LED the long leg is positive terminal and short leg is the negative terminal. If the LED not glowing then test the LED in the reverse polarity. Resistor have no polarity.

1.4. ON/OFF switch

It is used to turn ON and turn OFF an electrical device. It works just like a switch which we are using in our house.

1.5.1 Limit Switch - 1

Limit switch is a type of momentary switch used in electrical circuits to find some mechanical limit postions (stop). It have a lever. The lever is mechanically connected to the switch. When we push the lever, it will turn ON the switch and make one contact. When we release the lever, then the switch again moving to the OFF postion thus it will break the contact. The image represent one type of limit switch. It have only 2 contacts. The contacts will make connection when we push the lever.

1.5.2 Limit Switch – 2

It is the same type of limit switch but it have 3 terminals. One is common terminal (normally connecting to the powersupply) and other two are the output terminals. When we push the lever, the common terminal will make contact with the NO (normally open) terminal and disconnect from NC (normally closed) terminal. When we rerlease the lever the NC will connect to the common terminal and NO will disconnect from the common terminal. The terminal are indicated on the switch body. In this case the black wire is Common, Red wire is NC and the Green wire is NO.

1.6. Breadboard

It is a prototyping tool to create electronic circuits using discrete components. It is used to connect the components together without the soldering process. So normally it is used for temporery circuit testing purpose. It contain lot of holes in which we can insert the component legs. The holes are connected together internally in a pattern which is shown below. So we can connect components based on these internal connections.

1.7. Motor Driver Board (PCB)

It is a PCB (printed circuit board), which contain a motor driver IC (integrated circuit) used to drive a motor by giving some weak signal in the input pins. Basically it is works like an amplifier. It produces higher current in the output compared to the small input signal current. It is capable of controlling 2 motors simultaneously. The LED indicates the input power supply availability. Using this PCB we can rotate the motor in both clockwise and anticlockwise direction by changing the input signal polarity. The output is taken from the green screw terminals, power supply given to the centre pins (5V and GND) and the input motor controlling signal given to the side terminal in each side.

1.8. IR Sensor Module

It is a sensor PCB which detects the obstacle in front of the sensor (like proximity sensor). It contains an IR LED and a photo diode. The IR LED produce IR light and it hit the obstacle, the reflected light is detected by the photodiode then the IC in the PCB produce output signal based on the received signal from photodiode. The black coloured one is the IR photodiode and the transparent one is the IR LED. The variable resistor (preset) in the PCB is used to control the sensitivity (range of the obstacle) of the circuit. The red LED indicates the obstacle detection.

Note: The sunlight makes interference with this module. Because sunlight contain IR light, so the sun’s IR light is also detects by this circuit. So it will wrongly produce continuous output signal in the presence of sunlight. So it is important to avoid falling sunlight on this sensor module to avoid the false output. Use this module in indoor conditions.

1.9. IC (Integrated Circuit)

Here this kit contains NE555 IC for the light controlled RoboCar project. It is an 8 pin IC which used as a switch here. It produces output based on the signal from the LDR (light dependent resistor). IC is not a discrete component. Inside the IC which contains lot of transistors, resistor, diodes, etc. That is, basically the IC contains a big circuit inside the plastic package. So IC is useful for saving the space, power, money, etc. The IC have a polarity (orientation) based on the pins. The pin numbering style is given below. The counting starting from the left side of the notch or circle in the IC and continue counting in the anticlockwise direction (in the given orientation).

Note: Wrong orientation will destroy the IC permanently. Double check the pin connections after circuit wiring.

1.10. LDR (light dependent resistor)

It is a resistive sensor used to detect presence and intensity of the light which falling on the sensor. Its resistance is decreases based on the light intensity. More light means less resistance and less light means more resistance. It has no polarity. We can connect it in any orientation like the normal resistor

2.1. Glowing an LED (In 3V)

• Put two 1.5V cells in the battery holder in the right orientation (avoid short circuit between red and black wire)
• Make all the connections as shown in the breadboard circuit image
• Ensure the correct polarity of the LED (long leg to the battery positive [red])
• Resistance value is 1K (colour code is brown, black, red, gold)

2.2. Batteries in Series in LED Circuit (6V)

• Put 1.5V cells in both the battery holders
• Connect the battery in series as shown in the image (red to black between the battery holders) In this series connection LED glows brighter. So the conclusion is that, in series connection the battery voltage increased. This is because the LED glows brighter.

2.3. Batteries in Parallel in LED Circuit (3V)

• Connect the two battery holders in parallel, red wire to red and black wire to black In this series connection the LED brightness is same as the first experiment (LED with single 3V battery). This is because in parallel connection the voltage remains the same.

2.4. LED Circuit With ON/OFF Switch

• Use one battery holder here (3V)
• Connect the ON/OFF switch in between the battery and LED (switch is in series connection) When switch is in OFF position, it will break the circuit and block the current flow to the LED. When it is in ON position, it will make the circuit and allow a current flow to the LED.

2.5. LED Circuit With Limit Switch

• Here we replace the ON/OFF switch with a Limit switch (limit switch with 2 wires) The 2 wires from the limit switch will make the circuit when we press the switch lever, so it is a normally open (NO) switch. LED will light up when we press the lever and turnoff when we release the lever.

2.6. Motor Circuit with Battery (3V)

• Connect the robot wheel to the geared motor and tight the screw present inside the wheel
• Connect the Battery and the motor wires to the breadboard as shown in the diagram
• You can do the above experiments in this case also, that is the series connection of the switch and the limit switch

Note: If battery charge is low then the motor will not start, then you just rotate the wheel then it will start the rotation.

2.7. Reversing the Motor

• For reversing the motor just reverse the motor wire connection or the battery wire connection. Just interchange the connections. Check below image and check the motor wire colour with the previous circuit

2.8. Motor in 6V (Battery in series connection)

• Connect the two battery boxes in series manner as did in the previous LED experiments
• Then connect the motor to the battery through breadboard The motor will rotate faster because in series connection the battery voltage will increase. Here it is 3V +3V = 6V.

2.9. Three Wire Limit Switch Operation

In this experiment we will study the operation and use of the 3 wire limit switch. It will make one contact and break one contact when we push the lever. The pins are known as COM (Common), NC (Normally closed) and NO (Normally open). Normally we connect +ve or –ve power wire to the COM terminal and take outputs (connecting loads) from the NO and NC contacts. The given wiring diagram represents the operation of the limit switch.

• Connect all the components based on the given diagram
• The name of each pin of the limit switch is indicated in its body
• Double check the connections (check LED polarity once again) COM – Black wire, NC – Red wire, NO – Green wire (limit switch wire colours) Resistors are 1Kilo Ohm.

3.1. Mechanical and Electrical Connections

1. Take all the components as shown in the image (chassis, wheels, motors, battery holder with cells, breadboard, long nuts and bolts
2. Take one small and one medium size screwdriver and one plier as tool
3. Take one motor
4. Place the motor in the chassis, ensure the correct position based on the circular projection (check the given image)
5. Using the long nut and bolt tight the motor to the chassis
6. Use screwdriver and pliers carefully (Safety First)
7. Place the second motor in the same way
8. Put the motor wires through the holes in the chassis one by one as shown in the image
9. Do it carefully otherwise it will destroy the wire
10. Take the robo wheel and place it in the gear motor’s shaft
11. There is a small screw in the wheel, tight it carefully by the small screwdriver
12. Place the small breadboard in the chassis using the double sided tape in the breadboard
13. Place the battery holder behind the breadboard as shown in the image using the double sided tape
14. Avoid the short circuit between the battery terminals
15. Connect the two motors in parallel to the battery through the breadboard , connect the same colour wires of the motors together otherwise the motors will rotate in opposite direction
16. Also connect the ON/OFF switch in between the battery and the motors (keep in OFF position)
17. Check below circuit
18. Double check every connections once again
19. Test the circuit by turning on the ON/OFF switch
20. By changing the battery polarity (interchange the battery wire) you can move the robo car backwards
21. Also you can replace the ON/OFF switch with the 2 wire limit switch
22. Try different combination of circuits that we studied earlier

3.2. Robo Car In 6V (Battery in series)

1. Place second battery box above the first one using the double sided tape
2. Connect the two batteries in series connection as given in the circuit diagram
3. Replace the normal ON/OFF switch with the 2 wire limit switch
4. In series connection the voltage will increase thus the motor speed will increase

3.3. Turning The Robo Car

We can easily steer the robocar by turn on and turn off each motor simultaneously. If the right side motor disconnected (turned off) and the left motor connected (turned on) to the battery, then the car will make a turn to the right side. Also we can turn the robo car to the left side by doing the opposite connection (right motor ON and left motor OFF).

1. Disconnect one motor from the breadboard
2. Connect 2 wire limit switch in-between the connected motor and the battery
3. Check the circuit with the given diagram
4. You can interchange the connection and thus you can change the direction of turning

3.4. Rotating The Robocar

Here we are going to rotate the robocar with respect to a point without changing its position. For this we want to connect the two motors in parallel with opposite polarity (white to the ash and ash to the white colour). So both the motors rotate in opposite direction and thus it will just rotate without any displacement.

1. Connect the motor wires in opposite polarity. Ash wire to the white wire
2. Connect a switch (ON/OFF) inbetween the battery and the motor
3. Check the connections with the given circuit you can interchange the battery polarity, then it will rotate in the opposite direction.

3.5. Adding Blinking LED To Robo Car

Here we are going to add a blinking LED to the robo car. The blinking LED circuit is created by using a limit switch. The limit switch (2 wires) is connected under the robo car near to the gear motor. The shaft of the gear motor pushes the limit switch lever and releases the lever when it is rotating. So the LED connected to the limit switch will turn ON and OFF continuously when the wheel is rotating. So by this way we can create a blinking LED circuit to the robo car.

1. Remove the previously connected wheel from the left side motor
2. Unscrew the bottom nut and bolt using a screwdriver
3. Place the 2 wire limit switch inside the chassis as given in the image and screw the limit switch to the motor and chassis using the very long screw provided with the kit
4. Before tightening the nut ensure the proper positioning of the limit switch, at the proper position it will turn on off when we rotate the wheel, so checking the right position by rotating the wheel and listen the switching sound from the limit switch
5. Fix the wheel to the motor and tight it
6. Take the wire through the chassis hole to the outside like we did in the case of motor wire
7. Now wire the breadboard circuit as given in the diagram
8. Here ON/OFF switch is not connected, you can add switch in your circuit

THANK YOU

“Stay Creative and Stay Safe”

Part 1 is Over. Part 2 will Come Soon…………

Please watch Part 1 video for more understanding.

For more interesting projects please visit my webpages,

https://www.instructables.com/member/YADUKRISHNAN%20K%20M/instructables/

https://www.youtube.com/channel/UCTaMdoiwlfG7iGWML0kQKIA/videos

https://0creativeengineering0.blogspot.com/

Created By,

Yadukrishnan K M