A grass cutting mobile robot includes a body and a blade assembly connected to the body and rotatable about a drive axis. The blade assembly includes blades, a housing to hold the blades, a coupling latch configured to lock the housing to a drive shaft of the mobile robot, and a spring that connects the blade to the coupling latch. The housing is configured for coupling to an actuator so that the housing is rotatable about a drive axis, and receives a shaft that connects the housing to the actuator. The shaft includes a groove or an undercut therein. The coupling latch is rotatable within the housing to move an engagement end towards, or away from the groove or undercut. The engagement end is positionable within the groove to lock the housing to the actuator.
