Robots With Warm Skin Know What They’re Touching

Usually, if your robot is warm to the touch, it’s symptomatic of some sort of horrific failure of its cooling system. Robots aren’t supposed to be warm— they’re supposed to be steely and cold. Or at least, steely and ambient temperature. Heat is almost always a byproduct that needs to be somehow accounted for and dealt with. Humans and many other non-reptiles expend a lot of energy keeping at a near-constant temperature, and as it turns out, being warmish all the time provides a lot of fringe benefits, including the ability to gather useful information about things that we touch. Now robots can have this ability, too.

Most of the touch sensors used by robots are force detectors. They can tell how hard a surface is, and sometimes what kind of texture it has. You can also add some temperature sensors into the mix to tell you whether the surface is warm or cold. However, most of the time, objects around you aren’t warm or cold, they’re ambient—whatever the temperature is around them is the temperature they are.

When we humans touch ambient temperature things, we often experience them as feeling slightly warmer or colder than they really are. There are two reasons for this: The first reason is that we’re toasty warm, so we’re feeling the difference in temperature between our skin and the thing. The second reason is that we’re also feeling how much the thing is sucking up our toasty warmness. In other words, we’re measuring how quickly the thing is absorbing our body heat, and in even more other words, we’re measuring its thermal conductivity. Try it: Something metal will feel cooler to you than something fabric or wood, …[Read more]