Multi-contact haptics: the innovation that allows you to feel different sensations simultaneously on the same surface

In our day-to-day life we are interacting a lot with machines through various interfaces, which are mostly relying on our vision or hearing to provide us sensory feedback. Touch is often put aside, while it is the sense we are trusting the most. Through haptics interfaces, based on the science of touch, we can now address this growing need of tactile feedback in HMI. However, there is still a limit: it is impossible to feel different sensations simultaneously on the same surface… Until now!

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To bring back the sense of touch in the interfaces, Actronika is generating vibrations propagating through the touched surface to produce tactile illusions for specific interactions, such as button clicks for instance. To do so, one or several haptic actuators are integrated to move the contact surface and transmit the vibration to the user's skin.

However, with this approach, the whole surface motion is roughly driven by the same vibration. Thus, you cannot experience multiple differentiable tactile sensations simultaneously across the interface… To allow this, our team is developing the so-called Multi-contacts Haptics.

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What is Multi-Contact Haptics?

Imagine interacting on a shared touch screen, such as a control panel inside your car, and only experience the tactile feedback associated with your interactions without any spurious interference due to another user’s actions. This is now possible with this technology that offers the possibility to generate different haptic feedback simultaneously on multiple contact areas of a given surface. 

With the Multi-Contact Haptics technology, you can:

• differentiate the haptic feedback for different users interacting with the same interface
• provide various tactile stimuli simultaneously on any given interface
• allow differently abled people to interact with the added sense of touch

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How does it work?

Such a vibration control relies on the use of what is called the dynamic behavior of the system.

As you can see on the image above, every system possesses specific deformation modes occurring at specific frequencies of stimulation. Thus, by combining them, we can produce different vibration profiles on given locations of a surface simultaneously.

To do so, several actuators attached to the surface are driven independently and a calibration is performed to identify their contribution to this dynamic behavior.

Then, from the touched positions, we can compute the appropriate driving signals for each actuator to generate the targeted haptic effects on each of the contact points.

Shared screens or control panels, virtual keyboards or gamepads… These are just a few examples of the possible applications we can foresee.

Any user interface implying simultaneous interactions could benefit from such localized haptic feedback.

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