Haptic Interfaces

Haptics is the study of human touch and interaction with the external environment via touch. Haptic interfaces are a class of human computer interaction (HCI) devices that predominantly appeal to this particular sensory modality. Touch is unique as a human sense in that it can be used to gather information regarding the external environment and also to interact with it.

Although touch is employed when using HCI devices such as the mouse, tracker ball, light pen and keyboard, these are not true haptic interfaces, as feedback is provided primarily by other channels, typically visual, via a monitor. Haptic interfaces differ from these devices in that not only can the operator interact with the device, they can also be used by the operator to gather data regarding simulated object properties. Hence, true haptic interfaces are defined as those that allow both "input" and "output" with the simulated environment.

A typical device will take the form of a framework with one or more degrees of freedom (DOF), usually allowing exploration of a 3D workspace. The user interacts with the device via a probe, thimble or handle which is attached to the distal point of the mechanism. The apparent DOF of the device are then selectively constrained in order to convey the illusion of contact with a rigid surface.

Haptic interfaces were established out of the field of tele-operation, which was then employed in the remote manipulation of radioactive materials. The ultimate goal of the tele-operation system was "transparency". That is, a user interacting with the master device in a master-slave pair should not be able to distinguish between using the master controller and manipulating the actual tool itself. Early haptic interface systems were therefore developed purely for telerobotic applications, and not to serve as HCI devices for virtual reality applications.

Typical applications include training tools for medical tasks, such as minimally invasive surgery and veterinary applications. Examples of other novel uses of haptic devices include teaching aids, and in applications in the fashion and textile industry, where virtual fabrics could provide tactile information for designers and potential buyers over the Internet. Haptic interfaces can also provide vital assistance to visually impaired computer users, particularly with the advent of visual dependant graphical user interfaces.