When is a click not a click?

by Wendy Sadler

Last week the trackpad on my laptop stopped working. It wouldn’t click and seemed to be stuck down. It was surprising how essential this little piece of technology is to getting anything done, so I went to the Apple store to get some help.

In my head I was blaming the kids for spilling something sticky that had got into the mechanism and got it stuck. But then I was told that the trackpad doesn’t in fact move – it is a fixed plate! What?! How come I can feel it clicking then?

Haptic feedback – or in Apple terms – the ‘Taptic engine’.

It’s all in your mind…

Image courtesy Wikimedia Commons

Image courtesy Wikimedia Commons

You aren’t actually feeling a click at all – it’s an illusion in your mind. Haptic feedback is when something gives you a physical feeling – making you believe you are touching something or experiencing something that isn’t really there. Haptic is short for “hapteshi” – a greek word meaning ‘to touch’. Scientists have studied ‘human haptics’ for many years. We have an incredibly complex system for sensing the world through touch. Our hands have 22 joints, which give us 22 degrees of movement to explore the world. As we explore the world we get two different types of feedback; kinaesthetic and tactile.

The kinaesthetic bit is from the muscles and joints in your arms and hands and things called ‘proprioceptors‘ which send information to your brain on shape and location of things you can feel. Sometimes these receptors can get confused if you have a brain injury, as happened to our colleague James, and for a while he literally couldn’t tell where his legs were without looking at them! Here he is explaining proprioception:

The second bit of information is tactile and this comes mainly from the sensors just under your skin that let you feel textures and specific locations of objects.

Haptic feedback is how technology can be used to make your body feel something that isn’t there.

Engineers are using the idea to develop haptic tools, that allow surgeons to practice virtual surgery that gives feelings of what it will be like to cut into different parts of the body without them having to practice on someone for real.

How does it work?

Inside the macbook touch pad there are tiny force sensors made of electromagnets. When they detect a force they generate a vibration at that same point on the pad which makes it feel like the pad has been pushed down.

I was kind of blown away by this, as the sensation is so realistic. All my laptop needed was a software reboot and the ‘click’ response came back. Even though my brain now knows the trackpad doesn’t move in that way I still can’t get my head to believe it. That’s how effective it is.

Image courtesy Wikimedia Commons

Image courtesy Wikimedia Commons

This has huge potential for the world of robotics and virtual reality. There are haptic systems that let you feel like you are stroking a dinosaur! Imagine combining this with immersive VR headsets and you will soon be able to experience amazing worlds that involve the sense of touch. Our newest space made simple team member Mat Allen is doing all kinds of exciting VR work on astronomy and virtual visits to places you couldn’t usually go. I think all we need now is to add in the haptic feedback and you’ll not only be able to visit the International Space Centre (in 3D and 360 visuals) but you’ll be able to wear special gloves and reach out and press all the buttons to make things happen.

In the latest version of the taptic engine Apple have added the capability to do a number of different types of click just by applying different forces. A stronger click is detected and a different function is done. Soon all smart phones will use this idea to generate haptic feedback when typing to make writing on a touchscreen easier. Keyboards that give you physical feedback are still preferred by many for typing, so this could be a way of making gadgets of the future even smaller and lighter.

And knowing the weight of the laptop bag I haul around, that has to be a good thing!


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Posted in Biology, Physics, Technology