How can it be done?

When a finger touches an object, 3 different informations can be perceived

• thermal information (hot/cold sensations)
• force feedback (obstacle detection)
• tactile information (roughness)

We restricted ourselves to simulating flat and smooth surfaces, to avoid the roughness rendering issue. The thermal information is rendered thanks to a TEM (thermoelectric module), which is able to heat/cool efficiently, with better thermal performances than required for touch. The TEM lays on a xyz positioning table, which can move to any position in its workspace, simulating the presence of any surface.

How is a rendering session done practically?

The finger of the user is attached to an haptic arm with Velcro. When the user moves his finger, the movement is tracked by the haptic arm and the information is used by the software to control the movement of the virtual finger.
Using the informations of the haptic arm, the motorised xyz table follows the real finger so that it is ever under it, at the height of the local surface.
When the virtual finger touches the surface, the thermal rendering begins, following a thermal flow scenario, that was calculated before for each material, taking into account the ambient temperature and the finger temperature, which was measured at the beginning of the rendering session.