# Curvature Sensing and Control of Soft Continuum Robots Using e-Textile Sensors
## 1 Introduction  
Soft continuum robots are a type of robot defined by their flexible and deformable structures, enabling continuous curvature and smooth movements. These robots are particularly useful in applications requiring precise and delicate manipulation, as well as navigation through complex and constrained environments [1, 2]. Unlike conventional robots, which are limited by their rigid structures, soft robots are adept at maneuvering through intricate spaces, performing delicate operations, and safely interacting with humans. Continuum robots, with their elastic frameworks, demonstrate this flexibility, being capable of bending in nearly limitless ways due to their elastic backbones [1]. These robots are constructed from various soft materials, such as rubber [3], polyamide [4], silicone [5], and nitinol alloy (NiTi) [6], to achieve their remarkable adaptability. The inherent flexibility of soft robots is crucial in applications like minimally invasive surgery [7, 8], search and rescue missions [9, 10], and human-robot interaction [11], where the ability to adapt to and navigate unpredictable environments is vital. However, this same compliant nature also presents unique challenges in sensing and control [12, 13, 14]. As the demand for soft robotics grows, it is essential to develop sensing systems that not only align with their flexible characteristics but also provide the precise feedback necessary for complex tasks [15, 16]. Various methods have been explored for shape sensing in continuum robotic systems, including fiber optic sensor-based approaches like Fiber Bragg Grating (FBG) sensors [17], electrical impedance techniques [18], electromagnetic (EM) tracking [19], and imaging systems [20]. However, each of these techniques has drawbacks that limit their effectiveness, particularly in Minimally Invasive Surgery (MIS), where the specific demands of the application pose challenges for their integration with continuum robots. While FBG sensors offer notable shape-sensing precision, their widespread adoption is limited by the high costs of both the fiber material and the interrogation equipment, which hinders their practical use [21]. Similarly, electromagnetic positioning systems are frequently used but face significant challenges in surgical settings due to interference from metal objects and various equipment, which can compromise their accuracy [15]. Additionally, imaging methods, like computer tomography and magnetic resonance imaging, although effective, expose patients to ionizing radiation or X-rays, raising concerns about patient safety [22]. Accurately determining the shape of continuum robots remains a challenging task despite various existing methods. These methods must be affordable, safe for humans, and highly accurate. Since most continuum robots lack feedback control systems, integrating such systems is complex. Therefore, there is a significant need for a new method that is both flexible and cost-effective. To address the limitations of current rigid sensors, we propose a novel solution: the use of soft e-textile sensors to enhance the performance of soft continuum robots. Soft e-textile sensors are a new type of electronic fabric capable of detecting various physical properties around them and within the human body [23]. Recently, these sensors have gained popularity in wearable devices and health monitoring applications [24]. This approach is not only adaptable and cost-effective but also overcomes the limitations of existing rigid sensors. By leveraging the unique features of soft e-textile sensors, we aim to significantly improve the capabilities of soft continuum robots, addressing a crucial gap in the field of robotics. This research investigates the potential of employing e-textile sensors to extend the range of force measurements that the sensor can accurately detect. This enhancement is facilitated by the sensor's surface conductivity characteristics.