Development of the Ultralight Hybrid Pneumatic Artificial Muscle: Modelling and optimization

Abstract

Pneumatic artificial muscles (PAMs) are one of the key technologies in soft robotics, and they enable actuation in mobile robots, in wearable devices and exoskeletons for assistive and rehabilitative purposes. While they recently showed relevant improvements, they still present quite low payload, limited bandwidth, and lack of repeatability, controllability and robustness. Vacuum-based actuation has been recently demonstrated as a very promising solution, and many challenges are still open, like generating at the same time a large contraction ratio, and a high blocking force with enhanced axial stiffness. In this paper, a novel Ultralight Hybrid PAM (UH-PAM), based on bellow-type elastomeric skin and vacuum actuation, is presented. In particular, open-cell foam is exploited as a structural backbone, together with plastic rings, all embedded in a thin skin. The design and optimization combine numerical, analytical, and experimental data. Both static and dynamic analysis are performed. The weight of the optimized actuator is only 20 g. Nevertheless, a contraction ratio up to 50% and a maximum payload of 3 kg can be achieved. From a dynamic point of view, a rise time of 0.5 s for the contraction phase is observed. Although hysteresis is significant when using the whole contraction span, it can be reduced (down to 11.5%) by tuning both the vacuum range and the operating frequency for cyclic movements. Finally, to demonstrate the potentiality of this soft actuation approach, a 3 DoFs Stewart platform is built. The feasibility of performing smooth movements by exploiting open-loop control is shown through simple and more complex handwriting figures projected on the XY plane.

Rehabilitasyon Hizmetlerinde Yapay Zekâ Uygulamaları

“…Günümüzde yapılan son araştırmalar, hareketli bir taban platform üzerinde akıllı robot uygulamaları kullanarak (Şekil 3) daha sık antrenman yapımına imkân sağlayan robotik platformların ortaya çıkmasını sağlamıştır. Bu kapsamda üretilen Stewart Platformu; ayak bileği, diz ve eklemleri hareketlendirmek sağlığına kavuşturmak veya rehabilite etmek amacıyla kullanılmaktadır (Budaklı & Yılmaz, 2021;Joe et al, 2021;Kim et al, 2019;X. Liu & Wiersma, 2019;Yang et al, 2015).…”

Rehabilitation of the Human Bone-Muscle System

“…The basal ganglia participate in the initiation of walking and its proper progress. The cortex plans the action and the choice of a motor program when the cerebellum is dedicated to controlling gait and balance, as shown in Figure 1 [38].…”

“…( 12); the full-order SMC block consists of the Eqs. ( 12)- (15), which is chattering free and especially suiting for higher-order nonlinear systems with both uncertainty parameters and external disturbance [38]; the Bionic Joint Model block is the mathematic model of the concerned robotic joint as described in Eq. ( 16); and the ESO block is the extended state observer of the Active Disturbance Rejection Control [40], which is adopted to observe both the states of the robot system (z 1 and z 2 ) and the total disturbance z 3 of the robotic joint system.…”

“…In this section, an overview of different types of morphological designs, including actuators with convoluted (or corrugated) skin and pleated skin, is provided by highlighting their pros and cons. [38]; origami inspired [63]; structural instability shown in FEM model of the buckling actuator [92], and reproduced with permission [94].…”

“…Alternatively, Wang et al deduced the axial deformation by means of Castigliano's theorem, and derived the axial stiffness [25], as follows: [37]. (e) the Ultralight Hybrid PAM (UH-PAM) capable of 52% contraction [38]. (f) the Pleated Pneumatic Artificial Muscle (P-PAM) [39].…”