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