Foot Control of a Surgical Laparoscopic Gripper via 5DoF Haptic Robotic Platform: Design, Dynamics and Haptic Shared Control Jacob Hernandez Sanchez 1,2 , Walid Amanhoud 2 Aude Billard 2 and Mohamed Bouri 1 Abstract— Foot devices have been ubiquitously used in surgery to control surgical equipment. Most common applica- tions are foot switches for electro-surgery, endoscope positioning and tele-robotic consoles. Switches fall short of providing continuous control as required for precise use of instruments. We developed a haptic foot interface to provide continuous assistance in surgical procedures. This paper concerns the foot control of simultaneous five degrees of freedom (DoF) of a surgical laparoscopic gripper. We assess systematically preci- sion at controlling position and orientation at the target and closing of the forceps. Our controller provides position:position mapping between the foot and the robotic tool, as well as haptic feedback, compensating for gravity of the lower limb of the operator so as to alleviate fatigue. A dynamic model compensation and closed loop force feedback is used to achieve high transparency and backdrivability. The assistance is based on a novel type of haptic fixtures combining spring-damper with selective dynamic compensation in the direction aligned with the task of grasping, so as to simplify control of certain poses, made difficult due to the coupling between human lower limbs’ DoF’s. We experimentally evaluated the control strategy with six users on a position control surgical task in simulation. Results show the proposed assistance greatly eases the foot grasping task leading to higher completeness, efficiency, and lower mental and physical load. Index Terms— Foot Manipulation, Robotic Surgery, Foot- Robot Interaction, Surgery Training, Laparoscopy, Gripper I. I NTRODUCTION We target solo robotic surgery scenarios, in which the surgeon does not rely on an assistant and can control more than two instruments simultaneously. This may decrease the number of operating team members needed all at once in a surgical room. These people can then be re-allocated to other tasks, thereby increasing the throughput of surgeries made and shortening waiting lists [1]. Furthermore, communication issues and misunderstandings arising when working in a surgical team could be reduced [2]. Attempts for solo surgery using robotics can vary depending on the intended autonomy of the robotic assistants. For example, a solution could be to strive for fully autonomous robots to collaborate with the main surgeon [1], [3]. Here, we rather follow approaches using direct or semi-autonomous control [4] with emphasis in giving the surgeon the awareness of the interaction (forces and motion of the task) via haptic interfaces. As the surgeon’s hands are busy with tasks requiring high dexterity, the 1 REHAssist Group, Swiss Federal School of Technology in Lausanne EPFL, Switzerland. jacob.hernandezsanchez,mohamed.bouri@epfl.ch 2 LASA Laboratory, Swiss Federal School of Technology in Lausanne EPFL, Switzerland. walid.amanhoud, aude.billard@epfl.ch b) aim the target in 4dof Fig. 1: Foot position control of a surgical gripper assisted by a haptic shared control, performed by a surgeon in the Swiss Foundation for Innovation and Training in Surgery (SFITS), Geneva. When (a) a target appears inside the simulated torso, the foot platform operator (b) moves the tool to reach and align with the target both in position (three translations) and orientation (and then a blue visual cue appears), before performing a task of (c) grasping (and then a yellow visual cue appears). When there is a successful alignment and grasping, a new target appears after three seconds.If the user looses the alignment, it should open the gripper again and try again the task. We designed a shared control strategy for the onset of grasping. When the grasping gestures starts, the autonomous control renders a haptic virtual fixture in the foot that selectively eases the grasping, while increasing the resistance for foot gestures related to the positioning of the tool. Furthermore, the surgical robot takes over the position control of the tool while the operator performs the grasp. additional instruments will then be controlled by the feet. Controlling dexterously an additional instrument with the foot may be very demanding. Robotic assistance is hence desirable to supplement human control. This paper presents the design of a five degrees of freedom foot haptic interface to control a robotic gripper and a shared control strategy to ease its operation. This gripper may act as a laparoscopic retractor clearing the operating view in urological, gyneco- logical or visceral surgery [5]. Foot interfaces have been part of surgical operating rooms for many years, albeit not for performing manipulative tasks. Most medical foot interfaces consist of switches composed of one or a few push buttons, used typically, in on/off mode or to clutch. This can also be used for diathermy to enable an electrically heated probe via two (color-coded) foot switches. These are placed in front of the surgeon, who operates them with a single foot while being in a standing position [6]. Tele-robotic surgery consoles can use up to seven switches simultaneously for multiple non concurrent functions (e.g., instrument toggling, camera focus, electrosurgery, clutch, etc) [7]. Similarly, robotic endoscope holders like ViKy,