Highly-Integrated Muscle-Spindles for Pneumatic Artificial Muscles Made from Conductive Fabrics

Abstract

Pneumatic artificial muscles (PAMs) actuating bio-inspired structures are widely used to mimic the human musculoskeletal system. The research in this field can improve the understanding of the human’s physical abilities through a close recreation of its natural structure. This paper will introduce an enhancement to PAMs resembling the sensory-feedback of the muscles spindles’ group Ia and II afferent neurons. The artificial muscle spindle presented in this paper is embedded into the muscle and wraps around like its biological counterpart. Previous publications of artificial muscle spindles mostly aimed to output a signal, which correlates to the length of the muscle. This approach, however, aimed to recreate the natural muscle spindle as close as possible in regards to its functional principal and positioning inside of the PAM. By using conductive fabrics, a deeply embedded sensor type was created, which feedback correlates to the expansion of the PAM’s inner tube, as well as the pressure in-between of the inner tube and the outer braided sleeve. In this paper, a constructional approach on a biomimetic muscle spindle is introduced, including its Ia and II afferent neurons.