Engineering and robotic

Lets talk about electrical engineering and Robotic.

Wow, electrical engineering is challenging. We really need a very good in math, electric theory, and imagination. We use all the knowledge that we learn from lectures to solve the demand of human being.

Let say my recent assignment, how to build the automatic vacuum cleaner? The characteristic of this vacuum cleaner is can sense obstacle and turn it path way by it own, nothing can block it. If you put it on the table, it wont drop at the comer of the table.

Dealing with this, we actually divide this machine into 4 main parts.

First is mechanical part or in engineering we call actuator.

Second is sensor.

Third is circuit designing.

Last is programming.

Mechanical part, is the physical look of the vacuum clearer.

The shape is round. Because round do not have edge so it can turn with less friction if it collide with the obstacle.

The motor that is used is shunt 12Vdc motor. A rechargeable 12V battery is use to supply the voltage to the two motors, sensor and PIC.

Sensor, we are using 2 infra red sensors. The intensity of the reflected infrared is use as the data to send to PIC and use to control the movement of the motor. Infrared sensor is used because the sun emission consist less of infrared spectrum compare with visible light. Therefore this can increase the efficiency sensor.

The yellow colour sensor faces to front use to sense the obstacle. Red sensor faces to ground use to sense whether the vacuum cleaner is on the surface of an object(on the table to prevent drop from the high place).

How it turn?

Yellow sensor	Red sensor	Action of vacuum cleaner
OFF	OFF	TURN LEFT until red ON
OFF	ON	GO STRAIGHT
ON	OFF	TURN LEFT until yellow OFF
ON	ON	TURN LEFT until yellow OFF

If the red sensor facing down are ON(receive enough reflected infrared), the vacuum cleaner will move to straight only if the yellow front sensor is OFF(no reflected infrared received). If the yellow front sensor is ON, don’t care the red sensor is either on or off, the vacuum cleaner will turn left until the yellow front sensor is OFF and continue moving straight.

If you put it on the table, how it works?

If the red facing down sensors is ON it will move straight provided the yellow is OFF.. Once the red ground sensor and don’t care the yellow front sensor is ON or OFF, vacuum cleaner will turn to left until red sensor ON again and move straight again.

Circuit design,

How is the circuit of sensor?

How is the circuit of PIC?

How is the circuit for motor?

Remember to put a diode parallel to your transistor to prevent back EMF from motor.

Consist of amplification circuit and also comparator circuit by using op-amp.

We use DIPtrace to draw the circuit and transfer the image onto the copper board.

Programming

We are using PIC16F877A to receive all the data from sensor. We programmed the PIC to send the different output to the difference series of input. Let say if both sensor on ground is on, PIC will sent 5V to activate the connected 2 transistors. 2 Transistors will draw 12v from the battery to activate the both motor. If turning left, the left hand side of the motor is turn OFF and the right hand side motor continue moving. This creates the motion of turning left.