This study addresses the limitations of traditional assistive robotic arms by developing a smart continuum upper-body device inspired by the woodpecker's hyoid bone structure. Serving dual purposes, it provides flexible bionic prosthetics for individuals with disabilities while functioning as a "third arm" to enhance daily convenience and work efficiency for able-bodied users. By integrating biomimetic design with multimodal sensing, the system achieves natural human-machine interaction through its unique continuum structure and intelligent control, demonstrating innovative biomimetic applications in assistive technology. The device employs nickel-titanium alloy rods as the central backbone, combined with 360-degree servos and an Arduino-based control system. Furthermore, the design integrates an innovative power delivery system that eliminates exposed wiring while ensuring stable signal transmission. To achieve precise control in confined spaces, we implemented a Piecewise Constant Curvature (PCC) model to approximate arm deformation. Finally, performance was evaluated through gravity compensation and load-bearing experiments. Specifically, to address positional drift, we combined MPU6050 inertial sensing with OpenCV-based marker tracking, which enabled us to establish a sag prediction model for real-time compensation. Experimental results demonstrate reliable operation with 400-gram loads, and notably, at 40 cm extension, vertical error was maintained within 3-4 cm, confirming the system's practical accuracy.