You are doing the preliminary design of a simple 4 wheel robot that will follow

Question

You are doing the preliminary design of a simple 4 wheel robot that will follow a line and once started will never stop. In this case the electric motor is the motor that controls the steering. How many sub-systems do you think they are? Is there feedback between the electric motor and the positions sensors? If this was your team's senior project describe how you would break the system into subsystems so that the team could do as much work in parallel. If you were testing one system by itself, which time domain signal would you use to get a frequency response?

Explanation / Answer

A line following robot requires many part such as electric motor to make the robot move, sensors for sensing whether the robot is moving on a line or not. Sensor generates feedback signal depending on the presence of line. This feedback signal is then further givien to micro-controllers (signal processing board), Based on the feedback signal, it generates an actuating signal to control the motor, such that it retain on the line.

On the basis of above discussion, there are four subsystems that includes in the line following robot

1),Power supply section: It is one of the most important subsystem as it is responsible for supplying the enough power to the various electrical devices such as motors, micro-controllers and sensors. Each these device require different amount of voltage and current. For eg. Suppose you are using 12V DC motor so you will apply 12V DC voltage to DC motor, but this 12V DC voltage cannot be used for sensor because generally LED and LDR(Light Depending Resistor) are used as sensor to sense the presence of line. 12V DC voltage directly given to LED will damage the LED. Therefore, it is very neccasary for Power supply section to decide what amount of power is needed be each devices. To design this section, refer to datasheets of each device carefully.

2). Sensors: Sensor are used for sensing the presence of line. Suppose you are making a robot that follows black line. To sense this you can use a pair of LED and LDR as sensor. You will need two pair, one for right direction and one for the left. When Light ray from LED incident on black, it totally gets absorbed and LDR recieves no light and hence it resistance remains high and vice versa. The voltage across LDR can be used as feedback signal to thesignal processing board.

3). Signal processing board.: It process the feedback signal obtained from the sensot and generates the actuating signal that in turn control the direction of motors. You need to code the micro-controller for it. You can use arduino as it will be simple to code.

4). Motor driver circuit: This section is used after the signal processing board and before the motor. The output from micro-controller is not sufficient to drive the motor. To accomplish this various motor driver ICs are available such as L293D

You can distribute the above mention sub-systems and work on them parallely to accomplish the complete task.

For testing purpose, you can use Step signal and ramp signal. Step signal response will tell you the behaviour of system under sudden change while ramp response will tell teh behaviour of system under constant change.

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