In the deposition-based 3D printing process, the material stacking error during printing is a major defect that affects the entire process. Therefore, a printing method that compensates for the nozzle movement path during the printing process is needed. Our research mainly aims to demonstrate the effect of the compensation control method for path changes during the printing process by vision-based real-time feedback control. In this approach, the whole area can be monitored, and region of interest (ROI) is defined to observe a specific area. Two cameras observe the area around the nozzle and avoid the effects of occlusion. Additionally, binarization and edge detection are applied to the ROI. The feedback controller acquires the distance between the center coordinates and the target path in real time and calculates a compensation motion. In this research, a printing experiment is conducted using two types of materials. In the case of the 3D printing experiment for a cylindrical structure with a radius of 50 mm, the compensation effect was verified by the convex path change of the target path. Feedback experiments using mortar materials confirmed the effect of feedback of visual information in suppressing shape errors by compensating for convex path changes. The root mean square error of the nozzle trajectory was 2.43 mm relative to the predicted trajectory. The shape error relative to the circular shape decreased with each layer. These results showed the effectiveness of the failure suppression method based on visual feedback, which is sufficiently practical for large-scale printing processes.

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