Martin Gröger

DLR MiroSurge: a versatile system for research in endoscopic telesurgery.

PurposeResearch on surgical robotics demands systems for evaluating scientific approaches. Such systems can be divided into dedicated and versatile systems. Dedicated systems are designed for a single surgical task or technique, whereas versatile systems are designed to be expandable and useful in multiple surgical applications. Versatile systems are often based on industrial robots, though, and because of this, are hardly suitable for close contact with humans.MethodTo achieve a high degree of versatility the Miro robotic surgery platform (MRSP) consists of versatile components, dedicated front–ends towards surgery and configurable interfaces for the surgeon.ResultsThis paper presents MiroSurge, a configuration of the MRSP that allows for bimanual endoscopic telesurgery with force feedback.ConclusionsWhile the components of the MiroSurge system are shown to fulfil the rigid design requirements for robotic telesurgery with force feedback, the system remains versatile, which is supposed to be a key issue for the further development and optimisation.

Motion estimation in beating heart surgery

Minimally invasive beating-heart surgery offers substantial benefits for the patient, compared to conventional open surgery. Nevertheless, the motion of the heart poses increased requirements to the surgeon. To support the surgeon, algorithms for an advanced robotic surgery system are proposed, which offer motion compensation of the beating heart. This implies the measurement of heart motion, which can be achieved by tracking natural landmarks. In most cases, the investigated affine tracking scheme can be reduced to an efficient block matching algorithm allowing for realtime tracking of multiple landmarks. Fourier analysis of the motion parameters shows two dominant peaks, which correspond to the heart and respiration rates of the patient. The robustness in case of disturbance or occlusion can be improved by specially developed prediction schemes. Local prediction is well suited for the detection of single tracking outliers. A global prediction scheme takes several landmarks into account simultaneously and is able to bridge longer disturbances. As the heart motion is strongly correlated with the patients electrocardiogram and respiration pressure signal, this information is included in a novel robust multisensor prediction scheme. Prediction results are compared to those of an artificial neural network and of a linear prediction approach, which shows the superior performance of the proposed algorithms.

The DLR MiroSurge - A robotic system for surgery

This video presents the in-house developed DLR MiroSurge robotic system for surgery. As shown, the system is suitable for both minimally invasive and open surgery. Essential part of the system is the MIRO robot: The soft robotics feature enables intuitive interaction with the robot.

Reconstruction of Image Structure in Presence of Specular Reflections

This paper deals with the reconstruction of original image structure in the presence of local disturbances such as specular reflections. It presents two novel schemes for their elimination with respect to the local image structure: an efficient linear interpolation scheme and an iterative filling-in approach employing anisotropic diffusion. The algorithms are evaluated on images of the heart surface and are suited to support tracking of natural landmarks on the beating heart.

Image stabilisation of the beating heart by local linear interpolation

The stabilisation of motion on the beating heart is investigated in the context of minimally invasive robotic surgery. Although reduced by mechanical stabilisers, residual tissue motion makes safe surgery still difficult and time consuming. Compensation for this movement is therefore highly desirable. Motion can be captured by tracking natural landmarks on the heart surface recorded by a video endoscope. Stabilisation is achieved by transforming the images using a motion field calculated from captured local motion. Since the surface of the beating heart is distorted nonlinearly, compensating the occurring motion with a constant image correction factor is not sufficient. Therefore, heart motion is captured by several landmarks, the motion between which is interpolated such that locally appropriate motion correction values are obtained. To estimate the motion between the landmark positions, a triangulation is built and motion information in each triangle is approximated by linear interpolation. Motion compensation is evaluated by calculating the optical flow remaining in the stabilised images. The proposed linear interpolation model is able to reduce motion significantly and can also be implemented efficiently to stabilise images of the beating heart in realtime.

Structure driven substitution of specular reflections for realtime heart surface tracking

Specular reflections pose a particular challenge to intensity-based tracking approaches. The proposed scheme substitutes specular areas with respect to local image structures, extracted by the structure tensor. It can be applied to images of the beating heart prior to tracking and is shown to improve the estimation of local motion by natural landmarks significantly. The runtime complexity of the substitution scheme is analysed and time measurements of the different components show that it is well suited for realtime tracking.

Motion estimation in minimally invasive beating heart surgery

Motion estimation is a prerequisite for autonomous functions in robotic surgery. In beating heart surgery it allows motion compensation of the heart surface and thus a safe and secure operation. Algorithms for a short-term prediction of the heart motion are presented. Prediction increases the reliability of the motion estimation scheme, because short disturbances of the underlying tracking framework can be compensated.

Structure Tensor Based Substitution of Specular Reflections for Improved Heart Surface Tracking

Specular reflections pose a particular challenge to intensity-based tracking approaches. The proposed scheme substitutes specular areas with respect to local image structures, extracted by the structure tensor. It can be applied to images of the beating heart prior to tracking and is shown to improve the estimation of local motion by natural landmarks significantly.

Analysis of Colour Distributions of Anodised Titanium Clips and the Heart Surface for Tracking

Intraoperative organ motion, induced by heart beat and respiration, poses special demands to robot-assisted surgery. Recognition of this motion is required for motion compensation by robotic systems. Colour markers allow for robust motion estimation by colour tracking schemes. Anodised blue titanium clips, which can be attached to the heart surface, are proposed as colour markers. Analyses show that their colour distribution is separable from the colour distribution of the heart surface, allowing for robust colour tracking.