We make sense

Citation

Loughlin, C. (2004), "We make sense", Sensor Review, Vol. 24 No. 1. https://doi.org/10.1108/sr.2004.08724aaa.001

We make sense

We make sense

In this issue, we turn the tables on sensing technology and become the sensor ourselves. Haptics, the science of studying data obtained by means of touch, is our theme.

The main purpose of haptic devices is to give us the same physical feeling about an object as if we were in direct contact with it ourselves. The simplest example might be a remote teleoperator manipulator. The person operates what is known as the Master manipulator and a Slave manipulator in another room, on the sea bed, or halfway round the planet (or off it) moves in synchronisation with the Master.

Using such systems, surgeons can conduct remote operations, submersible ROV operators can grasp subsea cables and NASA scientists can pick up rocks on Mars. If all you want to handle are pieces of metal and rocks then you do not really need haptic feedback. You just instruct the gripper to close and it does so and applies a preset, and often very large, force.

However, what do you do if you want to grasp body parts, or even just push them out of the way? You need to have some means of feeling the forces that you are applying or more accurately the forces that the remote object is applying to the Slave.

If you pick up a bath sponge with your hands you can feel how hard you are squeezing it and can sense how firm or soft it is. This is what haptics is all about. At first glance you might think that creating this haptic sensation at the Master would be quite straightforward. After all, you just need force sensors in the Slave's gripper and actuators in the Master that apply the force being experienced to the operator's hand. In this issue we show how very difficult it is to create a realistic haptic environment, but also paradoxically, how quite simple devices can be remarkably successful.

The technology behind haptics is fascinating, but to me one of the major interests is that people are in the loop. We may not be able to quantify temperature as well as a thermocouple, or pressure as well as a barometric strain gauge; we cannot smell as well as dogs or see as well as eagles, but if you take the human package as a whole and include the best brain on the planet, then using people within the loop makes a lot of sense. Another quite wonderful thing about haptics is that the objects you feel do not have to be real. They can be virtual representations of real world objects or even not objects at all. The virtual simulation of body parts when linked with haptic interfaces such as the Phantom arm (refer pp. 16–29) allow trainee surgeons to practice their art without risk to life, limb or unfortunate rodent. The organs on which they practice can be completely virtual in that they never actually existed, in which case they can have average masses and textures. However they can also be virtual representations of actual organs, growths and all, obtained from 3D (and sometimes real time) MRI body scans. Surgeons rely heavily on their sense of touch to feel for abnormalities. Haptics can give them this remotely, and it could be argued that body scanners, computers and haptic devices can even give them an enhanced view of reality by magnifying defects to make them “firmer” than they actually are. Haptics can also be used to transform data into a form that we can feel. For example light intensity could be converted into firmness or, as is already happening in the oil industry, seismic data into texture. Whatever the transformation, the aim is to present data in a form that makes use of people's sense of touch to discover whole new ways of interpreting information.Imagine the benefits to a blind person of linking a 3D range scanner with a haptic interface.

Clive Loughlin