Output force augmentation

The output of the ECS can be considered as a generalized "force" applied to the CEV in opposition to the "force"applied by the disturbance. One reason control might be poor is that it has insufficient available force. It is simply overwhelmed by the disturbance. This might happen because the disturbance applies more force than the ECS can (the ECS controls well for low-force disturbances, but has only a limited range of control) or because the ECS has too low a gain in its output function (a problem over the entire range of control).

These two problems of insufficient force lead to the first kind of on-line help, mechanical force amplification, as shown in Fig 1. Mechanical force amplification can both extend the range of control and increase the user's effective gain and thus the precision of control (though note that this precision is limited by the precision of the perceptual function, which we consider in the next form of help). Examples of mechanical force amplification, chosen from a variety of levels of perceptual control,might include:

• Tools such as screwdrivers, which augment the torque that fingers can apply to a screw
• Weapons, which augment the force available to counter disturbances applied by an enemy to one's perceptual variables
• Servo-mechanisms, which permit teleoperation in conditions where one's personal range of control is non-existent
• speech-writers, who put into more persuasive terms the thoughts of one who wishes to perceive other people acting in a desired way.

All of these simply augment a "force" applied by the output of the ECS to the corresponding CEV. Each can be considered a "tool."

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