Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, 135 Yaguan Road, Tianjin, 300350, China.
School of Mechanical Engineering, Tianjin University, 135 Yaguan Road, Jinnan District, Tianjin, 300350, China.
Int J Comput Assist Radiol Surg. 2022 Jan;17(1):27-39. doi: 10.1007/s11548-021-02509-8. Epub 2021 Oct 9.
Stereo vision can provide surgeons with 3D images and reduce the difficulty of operation in robot-assisted surgery. In natural orifice transluminal endoscopic surgery, distortions of the stereoscopic images could be induced at different observation depths. This would increase the risk of surgery. We proposed a novel camera to solve this problem.
This study integrated the camera calibration matrix and the geometric model of stereoscopic system to find the cause of distortion. It was found that image distortions were caused by inappropriate disparity, and this could be avoided by changing the camera baseline. We found the relationship between camera baseline and observation depth with the model. A variable baseline stereoscopic camera with deployable structure was designed to achieve this requirement. The baseline could be adjusted to provide appropriate disparity.
Three controlled experiments were conducted to verify the stereo vision of the proposed camera at different observation depths. No significant difference was observed in the completion time. At the observation depths of 30 mm and 90 mm, the number of errors apparently decreased by 62.90% and 51.06%, respectively.
The significant decrease in number of errors shows that the proposed camera has a better stereo vision than a regular camera at both small and large observation depths. It can produce more accurate stereoscopic images at any depth. This will further improve the safety of robot-assisted surgery.
立体视觉可以为外科医生提供 3D 图像，并降低机器人辅助手术的操作难度。在自然腔道内镜手术中，不同观察深度会导致立体图像失真，这会增加手术风险。我们提出了一种新的相机来解决这个问题。
本研究将相机标定矩阵和立体系统的几何模型集成在一起，以找出失真的原因。结果发现，图像失真是由不适当的视差引起的，可以通过改变相机基线来避免。我们通过模型找到了相机基线和观察深度之间的关系。设计了一种具有可展开结构的可变基线立体相机来满足这一要求。基线可以调整以提供适当的视差。
进行了三个对照实验，以验证不同观察深度下提出的相机的立体视觉效果。在完成时间上没有显著差异。在 30mm 和 90mm 的观察深度下，错误数量分别明显减少了 62.90%和 51.06%。
错误数量的显著减少表明，与常规相机相比，该相机在小观察深度和大观察深度下均具有更好的立体视觉效果。它可以在任何深度产生更准确的立体图像。这将进一步提高机器人辅助手术的安全性。
