Neural Network-Based Active Load-Sensing Scheme and Stiffness Adjustment for Pneumatic Soft Actuators for Minimally Invasive Surgery Support

Abstract

To provide a stable surgical view in Minimally Invasive Surgery (MIS), it is necessary for a flexible endoscope applied in MIS to have adjustable stiffness to resist different external loads from surrounding organs and tissues. Pneumatic soft actuators are expected to fulfill this role, since they could feed the endoscope with an internal access channel and adjust their stiffness via an antagonistic mechanism. For that purpose, it is essential to estimate the external load. In this study, we proposed a neural network (NN)-based active load-sensing scheme and stiffness adjustment for a soft actuator for MIS support with antagonistic chambers for three degrees of freedom (DoFs) of control. To deal with the influence of the nonlinearity of the soft actuating system and uncertainty of the interaction between the soft actuator and its environment, an environment exploration strategy was studied for improving the robustness of sensing. Moreover, a NN-based inverse dynamics model for controlling the stiffness of the soft actuator with different flexible endoscopes was proposed too. The results showed that the exploration strategy with different sequence lengths improved the estimation accuracy of external loads in different conditions. The proposed method for external load exploration and inverse dynamics model could be used for in-depth studies of stiffness control of soft actuators for MIS support.

Effects of chamber shapes on maneuverability and control property of endoscope-support soft actuators

“…Echoing the research (Runciman et al, 2019;Xavier et al, 2021), we highlight the critical role of material properties in these interactions. Furthermore, our introduction of bilateral symmetrical air chambers, supported by previous studies (Stilli et al, 2014;Lu et al, 2023), represents a significant advancement in enhancing stiffness adjustability. This design not only bolsters resilience against external pressures but also optimizes control performance, crucial for the efficacy and safety of soft actuators in surgical applications.…”

“…This interaction highlights another crucial aspect: the necessity for soft actuators to adjust stiffness, ensuring a stable surgical view of the dynamic complexities of surgical environments. To address this requirement, a bilateral symmetrical air chamber design has been recognized, as supported by research ( Stilli et al, 2014 ; Lu et al, 2023 ), as an effective solution. This design ensures real-time adaptability and is notable for its inherent efficiency and practicality.…”

Addressing data imbalance in Sim2Real: ImbalSim2Real scheme and its application in finger joint stiffness self-sensing for soft robot-assisted rehabilitation

“…As an application of the ImbalSim2Real scheme, we focus on the finger joint stiffness sensing problem, taken as a prime imbalanced sim2real problem in the soft robot-assisted rehabilitation scenario. Soft Frontiers in Bioengineering and Biotechnology frontiersin.org actuators have been applied in various healthcare fields, such as rehabilitation (Wang et al, 2021), surgery (Lu et al, 2023), and assistance (Zhou et al, 2022). In particular, Heung et al analyzed the relationship between finger joint stiffness, soft actuator's angle, and air pressure, and hence developed an accurate analytic angle-pressurefinger joint stiffness model (Heung et al, 2020).…”