Robotic car using 8951 Microcontroller

Robotic Car is a miniature prototype car powered by batteries whose various movements can be control either manually or automatically, or the combination of both.  Here the command is given through keyboard; it would have been better if we used IR remote control or something of that kind rather than using keyboard for commanding. However, by realizing the complexities we have made simple using keyboard.

Block diagram of the project:

Some photographs of this model:

Robotic car model

Robotic car model

Project Description:
Keyboard section:
There are six switches in this section. They are

1. Turn left.
2. Turn right.
3. Stop.
4. About turn.
5. Park left.
6. Park right.

Circuit diagram of keyboard is shown bellow.

Keyboard circuit of the Robotic car

Car section:
There are many sub sections in this section. They are
Motor:
We are using a 5V dc motor to drive the vehicle. The speed of the vehicle and its strength is controlled by the proper use of pulley. The rear wheel of the vehicle is connected to this motor through a pulley. This motor is meant for moving the vehicle both in forward and backward direction. Microcontroller (8051) controls the forward and backward movement of the vehicle in the following manner:

Circuit diagram of Motor connection

Here in the above circuit, T1, T2, T3, T4 are the NPN power transistor (2N3055). A0, A1, A2, A3 are the signals coming from the micro controller. With the specific combination of A0, A1, A2, A3 we can change the direction of rotation of motor as follows:
Case I: When   A0=high; A3=high; & A1=low; A2=low
The motor rotates in clockwise direction

Case II: When   A0=low; A3=low; & A1=high; A2=high
The motor rotates in anti-clockwise direction

Case III: When   A0=low; A3=low; A1=low; A2=low
The motor stops the rotation.