gmapping navigation map building construction drawing package needs odometer information, and navigation is also needed.
The overall control structure of the mobile robot as shown below, wherein base_controller node information to subscribed cmd_vel lower machine (embedded control board) through a serial or other communications interfaces. Lower kinematic machine according to equation solver robot, the robot speed to convert the speed of each wheel, and then transmits the CAN bus (or other bus interface) for each wheel rotation speed to the motor driver board controls the rotation of the motor. Motor drive board motor speed closed loop control (PID control), and the number of encoder pulses per unit time received statistics, the wheel speed is calculated.
reference:
https://blog.csdn.net/zhu751191958/article/details/79322364