Hardware Reference
In-Depth Information
4. Since we are using only two sensors, the robot runs crisscross across the line. In
order to achieve smooth tracking of the line, a sensor array is used for driving the
motors using a control algorithm such as a PID control algorithm.
Objective complete - mini debriefing
In this task, we implemented the line following logic for our robot. In the next task, we will
discuss motor control to drive the robot This would be eventually integrated into the line
following logic.
Testing the motor driver circuit
In this project, we will use a pair of DC motors to drive the robot. We will use a dual H-bridge
(SN754410) driver to control the DC motors. We will use a sotware PWM library writen for
the Raspberry Pi. We chose DC motors for the following reasons:
1. DC motors are easy to operate and control using an H-bridge interfaced to
the Raspberry Pi.
2. There is a software PWM library that makes it easier to control the DC motors.
In this task, we will implement the DC motor control circuit and also write a program to
control the DC motors.
Prepare for lift off
We will use the sotware PWM funcion available with
RPi.GPIO
. The sotware PWM
funcion is available on versions greater than 0.5.3. We need to determine the
RPi.GPIO
version installed on the Raspberry Pi using a command-line terminal:
python
import RPi.GPIO
RPi.GPIO.VERSION
If the returned value is earlier than 0.53, the package can be updated as follows:
sudo apt-get update
sudo apt-get upgrade
We will be making use of pulse width modulaion to drive the DC motors. It is important
that you familiarize yourself with pulse width modulaion techniques to control a DC motor.
We also need to set up the DC motors for tesing by connecing the wheels to the motor
(something similar to the following figure):
