Compact surgical robot uses built-in feedback for micron-level accuracy

Controlling microrobots with extreme precision is vital in delicate surgical procedures, but traditional feedback systems are bulky and externally dependent. Now, researchers have developed a tiny surgical robot that sees and corrects its movements from within. By embedding a miniature camera and using internal visual tracking, the system enables real-time self-correction during motion, eliminating the need for external sensors. With onboard closed-loop control, this origami-inspired robot achieved micrometer-level accuracy and stability-even under external forces. The innovation marks the first demonstration of internal visual feedback in micro-robotic systems and paves the way for compact, autonomous surgical tools capable of operating deep inside the human body.

In microsurgery, every micron matters. Achieving precise movement in robotic instruments is complicated by environmental forces, user tremors, and the limitations of conventional actuators. Although piezoelectric beams offer excellent force and responsiveness, they struggle with drift and hysteresis unless supplemented by real-time feedback. Most systems rely on external cameras or strain sensors for correction, but these introduce bulk and wiring challenges-particularly problematic for minimally invasive applications. Meanwhile, compliant mechanisms promise compact and backlash-free motion but still require accurate sensing to be viable in clinical settings. Due to these challenges, there is a pressing need to develop a lightweight, high-resolution, internal feedback system to enable stable and autonomous microrobotic control.

In a pioneering advancement, researchers from Imperial College London and the University of Glasgow have created the first microrobot that controls its motion using fully onboard visual feedback. Published (DOI: 10.1038/s41378-025-00955-x) on May 29, 2025, in Microsystems & Nanoengineering, the study introduces a piezoelectric-driven delta robot enhanced with a built-in endoscope camera and AprilTag markers for internal visual tracking. This approach eliminates external sensing hardware and enables closed-loop motion correction within a self-contained system. The compact design and precise control open new possibilities for next-generation microsurgical tools.

The microrobot, inspired by delta mechanisms and origami structures, is actuated using piezoelectric beams integrated into a 3D-printed compliant framework. By replacing traditional joints with flexure-based elements, the team achieved precise, backlash-free movement across three degrees of freedom. For feedback, they embedded a miniature borescope camera beneath the robot’s platform to track AprilTag fiducials in real time. Using this onboard imagery, a PID-based control system continuously adjusted the robot’s motion to follow programmed paths and compensate for disturbances like gravity.

The robot was able to trace complex 3D trajectories with high repeatability. It achieved a root-mean-square motion accuracy of 7.5 μm, a precision of 8.1 μm, and a resolution of 10 μm. In side-by-side comparisons, the closed-loop system consistently outperformed open-loop control, especially when external forces were applied. The system also demonstrated resilience under load and maintained trajectory stability even in the presence of intentional disturbances. Compared with existing micromanipulators, this solution uniquely combines onboard sensing, simplicity of fabrication, and surgical adaptability. It’s the first system of its kind to integrate compact internal visual feedback for autonomous motion correction, offering an unprecedented level of autonomy and control for tools operating at micro-scale.

This development represents a paradigm shift in micro-robotics. Our approach allows a surgical microrobot to track and adjust its own motion without relying on external infrastructure. By integrating vision directly into the robot, we achieve higher reliability, portability, and precision-critical traits for real-world medical applications. We believe this technology sets a new standard for future surgical tools that need to operate independently within the human body.”

Dr. Xu Chen, lead author of the study

The robot’s compact, self-regulating design makes it ideal for applications in minimally invasive surgery, such as navigating catheters or performing laser tissue resections. Its internal camera system removes dependence on external equipment, enabling use in confined, sterile, or electromagnetically noisy environments. Future improvements-like higher frame-rate cameras and advanced depth tracking-could boost its responsiveness and z-axis resolution. With scalability down to sub-centimeter sizes, this platform has the potential to support tools for endomicroscopy, neurosurgery, and beyond. The ability to self-correct motion internally could soon make high-precision robotic surgery more portable, reliable, and accessible.