ABSTRACT
This chapter presents six control guidelines. Detailed information and examples accompany each guideline. Six methods of reducing control identification errors are labeling, color, shape, size, mode of operation, and location. Often these methods are combined. The control also may have special features. Once the proper type is selected, specify the control size and shape, amount of control movement, and actuation force. The control should offer sufficient resistance in its designed line of travel so that light touches do not activate the control. However, keep the force reasonable, especially at the limits of reach. The control systems can be divided into two general types: open loop and closed loop. In an open-loop system, there is a desired input or setting of the device but there is no feedback of what the device is doing to affect the desired input. In a closed-loop system, feedback affects the desired input. Consider turning a valve to let water flow.
