I am currently working with VESC to build a differential drive robot. For both the wheels, I tried to calculate the odometry from the erpm, but it has not been too accurate. I have also tried to use the tachometer and tried to calculate the rpm from that, but it has also been not that accurate. My motors currently have hall sensors. I am using the f1tenth repository with some modifications. In the VESC telemetry messages that I can see in ROS, there is pid_pos_now option there. Can someone explain what is this pid_pos_now? and if I can use this to calculate the rotor position and how?