RC Car Using DPDT Switches

INTRODUCTION

A remote control vehicle is defined as any vehicle that is remotely controlled by a means that does not restrict its motion with an origin external to the device. This is often a radio control device, cable between control and vehicle, or an infrared controller. A remote control vehicle or RCV differs from a robot in that the RCV is always controlled by a human and takes no positive action autonomously.

Remote control car includes the entities such as Mechanical elements such as wheels, Sensors such as IR sensors, proximity sensors, Motors, Driving mechanisms like pulleys, chains, Power supply unit, Electronic unit which includes circuits, Control unit which as microprocessors.

COMPONENTS USED·

1 DC Motors (500rpm)

· 2 DPDT switches

· 3 2- core shield wire

· 4 Battery (9V)

· 5 Plastic box (chassis)

· 6 Connecting wires and battery caps

· 7 Wheels (50mm diameter)

· 8 Remote control box.

PAPER PLANNING:

Before you start making your project you need a paper plan. Measure the following dimensions.

Length of the motor (excluding shaft)

Diameter of shaft of the motor

Inner hole diameter of the motor.

CHASSIS:

Chassis is a mechanical assembly for making a 4 wheel drive platform, where we can fix any controller board to drive the car. This is just the mechanical chassis, optionally as shown in the figure you can use 4 DC geared motors, and 4 wheels with rubber rings so you can make both variants.

Dimensions of chassis are as follows:

Length= 165 mm

Breadth = 105 mm and

Height of= 48 mm.

Mark suitable and equidistant points on both sides of chassis for the location of the wheels

Drill holes of diameter ½ inch at a distance of 80mm from each other at height of 24mm on both sides and at the top for the wire connections.

Fix the motors on the chassis with the help of nut.

MOTOR CIRCUIT CONNECTIONS

We know that a Motor rotates clockwise if connected normally and rotates anti-clockwise if the terminals are inverted .So this simple logic is used to make our car to move forward or backward. We need to control 4 motors here. So for forward movement of the car the two motors on the right side must rotate clockwise and the two motors on the left side must rotate anti-clockwise. For reverse movement of the car the two motors on right side must rotate anticlockwise and two motors on left side must rotate clockwise. Thus DPDT switches are helpful in movement of the car in both the directions.

REMOTE CONTROL CIRCUIT CONNECTIONS

To make anti-clockwise motion of motor, the polarity of supply must be inverted of polarity of supply in clockwise motion. For "Polarity Reversal" DPDT switches are generally used. This can be done by using the above circuit. Make sure that the wire passes through the hole drilled in the lid of the chassis. Fix the switches on the remote control box with the help of suitable fixing agents and make the circuit connections as shown in figure. Fix the wheels with the help of a nut. Give the chassis a decorative look.

WORKING PROCEDURE

The motors are fixed to the chassis body and the tiers are fitted to the motor shafts.

The 9V battery is connected to the center terminals of both DPDT switches.

RIGHT SIDE DPDT SWITCH: Connect the right side motors to the top terminals of right side DPDT switch. Connect it normally (+ ve and - ve ) so that the two motors on right side rotates clockwise when the switch is pressed to top position.

Just cross the connections of the top terminals to the bottom terminals using two wires, so that your right side motors rotate anti-clockwise when the switch is pressed to bottom position.

LEFT SIDE DPDT SWITCH: Connect the left side motors to the top terminals of left side DPDT switch. Connect it inverted (-ve and +ve ) so that the two motors on left side rotates anti-clockwise when the switch is pressed to top position. Just cross the connections of the top terminals to the bottom terminals using two wires, so that your left side motors rotate clockwise when the switch is pressed to bottom position.

Both the batteries are connected in opposite directions to complete the circuit. The DPDT switches help in changing in direction of current in both ways. This helps in motion in all directions. For motion in one direction the current should flow in same direction in all four motors for turning of car in any one direction-current should flow in only two of the motors on the same side.

Now the car is ready for the movement.

CALCULATIONS

THEORETICAL VALUES:

Speed of motor = 500 rpm

Diameter of wheel = 50 mm

Vth =

=Π×0.05×500×4/60

=5.23 m/s

ACTUAL VALUES:

Distance covered = 2.4 m

Time taken = 2 s

Vact = D/T

=2.4/2

=1.2 m/s

% Loss in velocity i.e., due to friction= Vth – Vact /Vth ×100

= 77.16%