collision sensing auto adjust with BDsensor
Homing: It can be triggered after the nozzle touch the bed while homing, it will move slowly up until the nozzle just leave the bed,then it will set this position as the 0 position of z axis. No need to calibrate the BDsensor before homing.
Auto calibrate: It can find the 0 position itself while homing,so no need to calibrate the z_offset with paper, it can also calibrate the BDsensor automatically
https://github.com/markniu/Bed_Distan...