A robotic service device is described for use on a robotic picking system grid. The robotic service device is capable of driving to any location on the grid order to perform maintenance operations or cleaning. Additionally, the service device may be used to rescue robotic load handling devices operational in the picking system. The robotic service device may include a releasable docking mechanism to enable it to dock and latch on to malfunctioning load handling devices. The service device may also be provided with cleaning capability and a camera to enable the condition of the grid and other robotic devices to be monitored.