Ricardo Beira

Influence of force and torque feedback on operator performance in a VR-based suturing task

The introduction of Minimally Invasive Surgery MIS has revolutionised surgical care, considerably improving the quality of many surgical procedures. Technological advances, particularly in robotic surgery systems, have reduced the complexity of such an approach, paving the way for even less invasive surgical trends. However, the fact that haptic feedback has been progressively lost through this transition is an issue that to date has not been solved. Whereas traditional open surgery provides full haptic feedback, the introduction of MIS has eliminated the possibility of direct palpation and tactile exploration. Nevertheless, these procedures still provide a certain amount of force feedback through the rigid laparoscopic tool. Many of the current telemanipulated robotic surgical systems in return do not provide full haptic feedback, which to a certain extent can be explained by the requirement of force sensors integrated into the tools of the slave robot and actuators in the surgeons master console. In view of the increased complexity and cost, the benefit of haptic feedback is open to dispute. Nevertheless, studies have shown the importance of haptic feedback, especially when visual feedback is unreliable or absent. In order to explore the importance of haptic feedback for the surgeons master console of a novel teleoperated robotic surgical system, we have identified a typical surgical task where performance could potentially be improved by haptic feedback, and investigate performance with and without this feedback. Two rounds of experiments are performed with 10 subjects, six of them with a medical background. Results show that feedback conditions, including force feedback, significantly improve task performance independently of the operators suturing experience. There is, however, no further significant improvement when torque feedback is added. Consequently, it is deduced that force feedback in translations improves subjects dexterity, while torque feedback might not further benefit such a task.

Tremo: an inspection climbing inchworm based on magnetic switchable device

TREMO is a compact magnetic climbing inchworm with the capability to move in complex ferromagnetic environments. The robot fits inside a cylinder of 500 mm in height and 120 mm in diameter for an approximate weight of 800 g. It has a modular configuration based on three energy autonomous sub-systems: an arm and two feet. The arm has five degrees of freedom. It has a central articulation with a stroke of 270°. Both ends of the arm have an innovative articulation based on a differential system. This allows unlimited rotation of 360° in the heading angles and 180° in the elevation angle. At both ends of the arm a camera is mounted. The feet are donut-shaped and are mounted around the camera. The climbing ability is based on the advantageous properties of Magnetic Switchable Devices (MSD) [1]. Each feet of the robot embeds three MSD for better compliance and stability of the adhesion to the surface. The three MSD of one feet together with their motors weight 32 g and can hold above 90 N.

Dionis: A novel remote-center-of-motion parallel manipulator for Minimally Invasive Surgery

The large volume and reduced dexterity of current surgical robotic systems are factors that restrict their effective performance. To improve the usefulness of surgical robots in minimally invasive surgery MIS, a compact and accurate positioning mechanism, named Dionis, is proposed in this paper. This spatial hybrid mechanism based on a novel parallel kinematics is able to provide three rotations and one translation for single port procedures. The corresponding axes intersect at a remote center of rotation RCM that is the MIS entry port. Another important feature of the proposed positioning manipulator is that it can be placed below the operating table plane, allowing a quick and direct access to the patient, without removing the robotic system. This, besides saving precious space in the operating room, may improve safety over existing solutions. The conceptual design of Dionis is presented in this paper. Solutions for the inverse and direct kinematics are developed, as well as the analytical workspace and singularity analysis. Due to its unique design and kinematics, the proposed mechanism is highly compact, stiff and its dexterity fullfils the workspace specifications for MIS procedures.

Modeling and design of a gripper for a robotic surgical system integrating force sensing capabilities in 4 DOF

This paper reports the design of a Minimally Invasive Surgery (MIS) gripper with four degrees of freedom force sensing capabilities. It will be used to provide force feedback during surgical interventions in which the surgeon will remotely manipulate surgical instruments through the use of a robotic arm directly inserted into the patients insufflated abdominal cavity. Suturing, dissection and ablation instruments will be attached on this 8 mm× 9 mm× 3 mm MIS gripper. Finite Element Analysis is used to model the gripper and determine the deformation matrix coefficients. Gripping and XYZ Cartesian direction applied forces can be measured with a resolution of 0.1N for a maximum force of 10N. However a significant difference between the predicted values by the Finite Element model and those obtained in the characterization of the force sensor is found. This divergence is due to misalignments of the strain gages located on the blades of the gripper. Future work will be focused on reducing misalignment of force sensors as well as other error sources.