An intelligent door lock system is provided with a position sensing device configured to be coupled to a drive shaft of a lock device. The position sensing device senses position of the drive shaft and assists in locking and unlocking a lock of a lock device. An engine is provided with a memory coupled to the positioning sensing device. A circuit is coupled to the engine and an energy source is coupled to the circuit. A device converts energy into mechanical energy and is coupled to the circuit, positioning sensing device and the drive shaft. The device that converts energy is coupled to the energy source to receive energy from the energy source.