Human-Robot Interaction Control Using Force and Vision

Physical human-robot interaction (pHRI) is an interesting topic for small-scale industrial robotics, where a user may need to share the workspace with a robot, as well as for service robotics. In the elderly-dominated scenario of most industrialized countries, service robotics is a solution for automatizing common daily tasks, also due to the lack or high cost of human expertise. The size of an industrial robot, or the necessary autonomous behaviour of a service robot, can result in dangerous situations for humans co-existing in the robot operational domain. Therefore, physical issues must be carefully considered, since “natural” or unexpected behaviours of people during interaction with robots can result in injuries, which may be severe, when considering the current mechanical structure of robots available on the market. In this special perspective, an improved analysis of the problems related to the physical interaction with robots leads to rediscuss most of the topics of mechanical design, planning, and control of robots [1]. The physical viewpoint is mainly focused on the risks of collisions or excessive force exchange occurring between the robot and its user: a too high energy-topower ratio may be transferred by the robot, resulting in serious human damages. Severity indices of injuries may be used to evaluate the safety of robots in pHRI. These should take into account the possible damages occurring when a manipulator collides with a human head, neck, chest or arm. Several standard indices of injury severity exist in other, non-robotic, domains. The automotive industry developed empirical/experimental formulas that correlate human body’s acceleration to injury severity, while the suitability of such formulas is still an open issue in robotics.