A machine system includes a machine which performs an operation on a workpiece passing through an operational area, a miss detection section which detects that a workpiece has passed through an operation limit line of the machine in an incomplete operation state, and a notification section which notifies information related to the missed workpiece based on information of the miss detection section.

Traction for a downhole tractor in a wellbore. A downhole propulsion system can provide a first traction module; a second traction module; and a controller configured to compare a first input parameter representing operation of the first traction module with a second input parameter representing operation of the second traction module. The controller can adjust a first output parameter of the first traction module and/or a second output parameter of the second traction module based on an input representing slip of the first traction module relative to the second traction module.