The Operation of Control Devices During Parabolic Flights: Influence of Weightlessness, Stress and Motivation

Investigations description

---------------------------------- Subjects will sit in a rack at a table in front of a 17" screen of an Eye Tracker system (Tobii® T60). The right part of the screen will be covered by a row of operating devices; two rotary knobs of different size, one turn switch and one simple push button. The construction of these devices is based on real ones on board the ISS. Integrated in three of these devices are force sensors (6D ATI® Nano17), which register grip torques and forces while subjects' manipulate the devices.

Four Vicon® Bonita cameras are positioned over the table and attached to a table-fixed metal frame. They will register hand dynamics throughout all grasping movements in normal gravity as well as in microgravity.

In accordance to a classical control task by Kramer (1999) subjects will be asked to control pointer instruments, which are displayed one below the other on the screen. These controls will be embedded in a real life scenario where subjects have to react on specific signals within this scenario: As soon as one of the displayed pointers reach a critical deflection, subjects have to react as fast as possible by grasping towards the associated control device, rotate or push it and turn back to the starting position. This action will bring the pointers back to an uncritical position. The pointers will move independent from the others. Additionally we introduce one compatible and one incompatible pointer-device connection, i.e. the upper pointer can be controlled with the lower device, the middle pointer with the middle and the lower pointer with the upper device.

Equipment used --------------------- Hand movements Hand movements are registered from above and the side by four infrared high-speed cameras (Bonita Vicon-Cameras - CE mark 0088) which register with 250Hz the 3D positions of ten small reflexive markers (attached by double sided adhesive tape to all fingertips and to the thumb of the subjects' right hand). The cameras are connected via cables with an Ultranet which is the central processing unit. The Ultranet is connected with a network cable to a corresponding desktop computer.