A robotic touchscreen totem for two-dimensional haptic force display

Current touchscreen-based haptic systems use contact friction to provide kinesthetic force feedback to the user. This paper presents the mechatronic design for a novel haptic interface which uses a steered wheel to provide kinesthetic force feedback on a large-format touchscreen. The goal is to display haptic constraints to a touchscreen user in the form of boundaries, area-of-effect fields, or paths. The constraints will allow the device to enforce or encourage motion corresponding with elements of the visual display. Haptic wall and maze applications were developed to demonstrate these functions. The device can exert up to 13.7 N of static friction force and penetrates a haptic wall by 6.0 mm in a head-on collision, while offering minimal resistance to motion along the wall. The magnitude of interaction force between the user and device is sensed with 11 mN resolution through displacement measurements of 3D-printed nylon flexures, designed to have uniform 7.0 N/mm stiffness in all directions parallel to the surface plane. Potential applications for the device are gaming, touchscreen accessibility, and upper limb stroke rehabilitation therapy.