Measurements for the thermodynamic model of a pneumatic muscle actuator

Abstract

The paper presents the selection of sensors and especially their placement for evaluating the thermodynamical model of a pneumatic muscle actuator. Pneumatic Muscles are undoubtedly one of the most promising actuators among the currently applicable modern muscle-like actuators. This actuator is, on the one hand, characterized by exceptional utility properties, the second highly non-linear and complex internal friction. Complicated and still not enough precise models currently do not allow this promising drive to expand behind the walls of experimental laboratories. This paper also provides a description of McKibben pneumatic muscle and represents the current state of its mathematical model. The main objective of this work is to extend the mathematical model of the pneumatic muscle, especially in the field of thermodynamics. The authors apply a method originally designed for pneumatic linear drives on pneumatic muscles, create a new thermodynamic model and discuss the results obtained. Subsequently, the method is significantly extended by another independent thermodynamic variable, and the newly proposed mathematical model includes the heat generated by friction, which exerts major influence on the behavior of the actuator. Importance of the extended thermodynamic model is demonstrated by simulations of ideal thermodynamic processes and, in particular, by comparing the present model with a realistic position servo drive system with pneumatic muscle. Sensor choice and placement on the muscle test bed is evaluated, and the obtained results are discussed.