A system is disclosed, comprising an array of sensors disposed on a plurality of aerial vehicles, a sensor array controller for controlling the plurality of aerial vehicles, a physical feedback mechanism for providing physical feedback to a user, the physical feedback mechanism being configured to be worn on the user's body, and a feedback controller. The sensor array controller is configured to reposition the plurality of aerial vehicles so as to provide a line of sight between each one of the plurality of sensors and a respective part of the user's body monitored by said one of the plurality of sensors. The feedback controller is configured to determine a current position of the user's body based on information obtained using the plurality of sensors, and to control the physical feedback mechanism to provide physical feedback to the user in dependence on the determined position of the user's body.