Implementation of a human-aware robot navigation module for cooperative soft-fruit harvesting operations

In the last decades, robotic solutions have been introduced in agriculture to improve the efficiency of tasks such as spraying, plowing, and seeding. However, for a more complex task like soft-fruit harvesting, the efficiency of experienced human pickers has not been surpassed yet by robotic solutions. Thus, in the immediate future, human labor will probably be still necessary for picking tasks while robotic platforms could be used as collaborators, supporting the pickers in the transportation of the harvested fruit. This cooperative harvesting strategy creates a human-robot interaction (HRI) that requires significant further development in human-aware safe navigation and effective bidirectional communication of intent. In fact, although agricultural robots are considered small/medium size machinery, they still represent a risk of causing injuries to human collaborators, especially if people are not trained to work with robots or robot operations are not intuitive. Avoiding such injury is the aim of this work which contributes to the development, implementation, and evaluation of a human-aware navigation (HAN) module that can be integrated into the autonomous navigation system of commercial agricultural robots. The proposed module is responsible for the detection and monitoring of humans working around the robot and uses this information to activate safety actions depending on whether the human presence is considered at risk or not. Apart from ensuring a physically safe HRI, the proposed module deals with the comfort level and psychological safety of human coworkers. The latter is possible by using an explicit human-robot communication strategy that lets both know of the other's intentions, increasing the level of trust and reducing inefficient pauses triggered by unnecessary safety actions. The proposed HAN solution was integrated into a commercial agricultural robot and tested in several situations that are expected to happen during cooperative harvesting operations. The results of an usability assessment illustrated the benefits of the proposal in terms of safety, efficiency, and ergonomics.