Applying Programmable Display Pushbuttons to Manned Space Operations

Abstract

American manned spacecraft have used a l a r g e number of d i s c r e t e dedicated switches In t h e decade and buttons t o allow astronauts t o monitor and control system functions.or so since t h e Space S h u t t l e was designed, t h e r e have been many improvements i n t h e area of control m u l t i f u n c t i o n a l i t y . One of these advances i s t h e development of programmable display pushbuttons (PDPs), which a r e illuminated pushbuttons w i t h displays c o n s i s t i n g of a matrix of LEDs t h a t can show preprogrammed information i n the form of alphanumerics or symbols. Our work i s designed t o study t h e parameters a f f e c t i n g t h e usefulness of PDPs i n manned space operations. complex Space S h u t t l e tasks by comparing c u r r e n t procedures and procedures involving the use of PDPs. user-PDP i n t e r f a c e for one typical Space S h u t t l e t a s k . We a r e simulating t h e performance of This paper discusses issues t h a t arose i n t h e course of designing the I NTRODUCTI ON Throughout t h e h i s t o r y of t h e American space program, manned spacecraft have used a l a r g e number of d i s c r e t e dedicated switches and buttons t o allow astronauts t o monitor and cont r o l system functions. The Space S h u t t l e cockp i t , f o r example, contains approximately 1500 switching devices, 300 annunciators, and 40 meter/electromechanical displays f o r status information and subsystem control operations. Many of these devices a r e required only d u r i n g s p e c i f i c phases of t h e mission. was designed, t h e r e have been numerous advances i n d i s p l a y and control technology. Many of these advances have been i n t h e area of control m u l t i f u n c t i o n a l i t y ; t h a t i s , providing t h e capab i l i t y f o r one piece of hardware t o serve mu]-t i p l e functions i n d i f f e r e n t modes of operation. Knowlton (1977) describes a method f o r o p t i c a l l y superimposing computer displays on i n p u t devices. This procedure can be used t o make computergenerated l a b e l s appear t o be temporarily i nscribed on a s e t of pushbuttons a t a console. Changes i n t h e software allow switching from one mode t o another, a s t h e v i s i b i l i t y , posit i o n , l a b e l , s i g n i f i c a n c e , and function of each button a r e under software c o n t r o l . In t h e decade or so since t h e Space S h u t t l e Nakatani and Rohrlich (1977) discuss t h e concept o f s o f t machines, machines t h a t use a combination of real-time computer graphics and a touch-sensitive position sensor coup1 ed with a video display terminal (touch s c r e e n ) . The graphics software makes t h e s o f t machine look l i k e a conventional hard machine through t h e generation of images of c o n t r o l s shown on t h e video display terminal ( e . g . , keys, pushbutton switches, and s l i d e potentiometers). screen enables t h e user t o touch and operate t h e s o f t c o n t r o l s i n the display a s i f they were hard c o n t...