4.1 Graphical Interface

The first is an analogue display of the input data with horizontal bars representing the input values, such as the grip force, the user control input and the degree of flexion of the fingers. The display can show sub sets of the full input data.

For example; the display can merely shows the user input channels. The usual (but not exclusive) user input, is electromyographic. These are the small voltages generated by muscles as they contract. These signals are amplified and used in their analogue form. An extensor muscle may be used to instruct the hand. The greater the muscle is tensioned, the wider the hand opens. Thus when the user relaxed the hand closes on its own. A second muscle (flexor) is then used to switch the hand into a HOLD mode so that the slip reflex is invoked.

The display can then show the two inputs as two horizontal bars. As the tension increases the length of the bars increase. This allows a new user to be assessed to their abilities to produce the correct signals and the levels required to operate the hand and to be trained on its use [9].

A second display is the simulation of the hand itself. The animation responds to the Electromyographic (EMG) input, opening and closing as the hand would. Objects of different shapes can be introduced into the hand and the trainee can operate the hand without any additional complications. Once the hand is fitted and in use, the analogue display can be used to guide the operator into the way the hand controls the object. The display can show the force input is used to show how the grip orientation is optimised for the particular object and if the slip reflex is used.