The neuromuscular system

Abstract

The aim of flight simulation is to create an environment for the pilot wherein he or she can perform the piloting task in such a way that the objective of the simulation, training or research, is reached. To simulate the flight environment in a simulator models describing the aircraft dynamic behavior and its systems, the atmosphere, the geographical and navigational environment, etc. are used. To fulfill his task, the pilot needs to perceive all relevant information and must have the means to control the simulated aircraft. This means that the pilot-aircraft interface, the cockpit with all its displays and controls, the aircraft motions, etc. has to be simulated accurately so that the pilot can perform in the simulator as in the real aircraft. Not only all cockpit systems have to provide the pilot with the proper stimulation of his senses but also the cockpit controls need to produce the proper control force-stick displacement characteristics. To make that possible not only all aircraft systems to be simulated have to be understood but also all human systems i.e. the characteristics of the senses (visual, vestibular, auditory, proprioceptive, etc.) and the actuation mechanisms have to be known. Based on this broad knowledge the pilot - aircraft interface for simulation can be specified, designed and employed. The MST Motion Working Group is currently documenting on the human capabilities and simulator systems. In this paper the neuromuscular system will be discussed. Both the physiology of the muscle and the sensors, the muscle spindle and the Golgi tendon organ, and the components of the nervous system regulating the force and position of the limb, as well as the adaptation of the neuromusculosketal system to the task requirements are discussed. Recently a neuromusculosketal system model was developed at Delft University. This model is used to explain the adaptation to three typical tasks in response to stick forces: resisting forces (maintaining a constant position), ignoring forces (minimizing muscle activity) and giving way to them (maintaining a constant force). Based on the model it is shown which parts of the system are adaptable and how the model parameters change to adapt the admittance, the external force/displacement characteristic, to the task.