The effect of geometry and material properties on the performance of a small hydraulic McKibben muscle system

Abstract

Fluidic McKibben artificial muscles are one of the most popular biomimetic actuators, showing similar static and dynamic performance to skeletal muscles. In particular, their pneumatic version offers high-generated force, high speed and high strain in comparison to other actuators. This paper investigates the development of a small-size, fully enclosed, hydraulic McKibben muscle powered by a low voltage pump. Hydraulic McKibben muscles with an outside diameter of 6 mm and a length ranging from 35 mm to 80 mm were investigated. These muscles are able to generate forces up to 26 N, strains up to 23%, power to mass of 30 W/kg and tension intensity of 1.78 N/mm 2 at supply water pressure of 2.5 bar. The effects of injected pressure and inner tube stiffness on the actuation strain and force generation were studied and a simple model introduced to quantitatively estimate force and stroke generated for a given input pressure. This unique actuation system is lightweight and can be easily modified to be employed in small robotic systems where large movements in short time are required.  Effect of the bladder stiffness on Muscle performance is studied. A new and more accurate equation to predict the muscle performances is proposed. A sealed actuation system suitable for robotic machines with low voltage water pump is introduced. AbstractFluidic McKibben artificial muscles are one of the most popular biomimetic actuators, showing similar static and dynamic performance to skeletal muscles. In particular, their pneumatic version offers high-generated force, high speed and high strain in comparison to other actuators. This paper investigates the development of a small-size, fully enclosed, hydraulic McKibben muscle powered by a low voltage pump. Hydraulic McKibben muscles with an outside diameter of 6 mm and a length ranging from 35 mm to 80 mm were investigated. These muscles are able to generate forces up to 26 N, strains up to 23%, power to mass of 30 W/kg and tension intensity of 1.78 N/mm 2 at supply water pressure of 2.5 Bar. The effects of injected pressure and inner tube stiffness on the actuation strain and force generation were studied and a simple model introduced to quantitatively estimate force and stroke generated for a given input pressure. This unique actuation system is lightweight and can be easily modified to be employed in small robotic systems where large movements in short time are required.

Biohybrid robot powered by an antagonistic pair of skeletal muscle tissues

“…The results show that the magnitudes of the actuations were controllable depending on the frequency and magnitude of the electrical field in the electrical pulses. When we selectively applied 1.5 V/mm, 50-Hz electrical pulses to the skeletal muscle tissues, the biohybrid robots achieved the largest actuation, with a 0.2 strain of the skeletal muscle tissues and a 90° joint rotation, indicating that the biohybrid robot had similar motions to that achieved by the living skeletal muscle [0.2 to 0.4 strain (27)] and joint movements of a human finger [85° to 100° (28)]. In addition, an analysis of the balance of forces in the bidirectional rotation, as shown in section S1, indicated that the friction force at the joint was too large to ignore and that the balance of tensions of the skeletal muscle tissues relative to the friction force at the joint determined the magnitude of the joint rotation.…”

Analysis on the Impact Factors for the Pulling Force of the McKibben Pneumatic Artificial Muscle by a FEM Model

“…diameter and force output around the pressure of 0.15 MPa implies that there is a pressure threshold for the PAM force, as theoretically supposed by Chou et al [4] and experimentally veri ed by Zang et al [13] and Sangian et al [28]. As demonstrated in Figure 7, while the in ated diameter derived by the FEM model reveals the morphological deformation of PAM, the equivalent diameter can reveal the mechanical behaviour of a PAM actuator.…”

Thermally activated paraffin-filled McKibben muscles

“…To consider the impact of bladder stiffness on the muscle performance, theoretical (Sangian et al, 2015) and semi-empirical (Meller et al, 2014) modifications have been added to the model.…”