A robot is operated in an autonomous mode of operation in which the robot autonomously selects a strategy to pick up an item. The item is moved from an initial location to a destination location using the selected strategy. It is determined whether one or more strategies are available to pick up the item in response to the item being dropped while the item is being moved from the initial location to the destination location. It is determined that a further strategy is not available to pick up the item. In response to the determination that the further strategy is not available, a human intervention mode of operation is entered.