Continuum Medical Robotics

  • Our work in Continuum Medical Robotics is focused on designing, modeling, and controlling compliant manipulators for minimally-invasive surgical interventions.  Commonly referred to as catheters, these devices are often constructed of rubber-like materials and are commonly actuated by cables, giving them impressive safety characteristics but also leading to nonlinear hysteretic behaviors which limit procedure complexity and success.  The following research is focused on maintaining the inherent safety of catheters while avoiding or compensating for their nonlinear behavior.
  • Faculty:
  • Michael Zinn – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Students:   
  • Ryan Penning – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Jinwoo Jung – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Justin Borgstadt – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Dusty Brunner – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Guru Subramani – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Funding:
  • National Science Foundation (NSF): National Robotics Initiative (NRI)
  • Wisconsin Innovation & Economic Development Research Program (IEDR)

    Recent work

  • Ph.D Thesis and Defense – Conrad, B.: Redundant Design and Adaptive Control of an Interleaved Continuum Rigid Manipulator Continuum manipulator compliance enables operation in delicate environments at the cost of challenging actuation and control. In the case of catheter ablation of atrial fibrillation, the compliance of the continuum backbone lends an inherent safety to the device. This inherent safety frustrates attempts at precise, accurate, and fast control, limiting these devices to simple, static ...
  • ICRA 2015 – Multi-Modal Localization Algorithm for Catheter Interventions Abstract— Localization of steerable catheters in minimally invasive surgery is critical with respect to patient safety, surgeon manipulation, and procedural efficacy. While there are many potential benefits to patients including shorter recovery times, less tissue trauma, and lower infection rates than traditional surgeries, localization of surgical tools is still an area of much research. Current technology offers several sensory modalities. However, each ...
  • ICRA 2015 – Closed Loop Task Space Control of an Interleaved Continuum-Rigid Manipulator A new manipulation approach, referred to as interleaved continuum-rigid manipulation, which combines inherently safe, flexible actuated segments with more precise embedded rigid-link joints has recently been introduced. The redundantly actuated manipulator possesses the safety characteristics inherent in flexible segment devices while gaining some of the performance attributes of rigid-link joint systems. In this paper, we ...
  • ICRA 2015 – Tackling Friction: An analytical modeling approach to understanding friction in single tendon driven continuum manipulators     Abstract: Tendon driven continuum robots have attracted a significant amount of attention in the last decade. As a result several discrete and continuous modeling approaches have been explored in order to understand their behavior. The following article proposes an analytical model describing the influence of frictional effects between the tendon and its conduit in tendon driven ...
  • Advanced Robotics 2014 – A Modeling Approach for Robotic Catheters: Effects of Nonlinear Internal Device Friction Abstract – Recently, robotic surge~ systems using passive flexible catheters have been developed for minimally invasive surgical applications – such as in the treatment of atrial fibrillation – where catheter control in the open chamber of the heart is required. The soft, atraumatic construction of these devices help reduce injury to delicate cardiac structures while providing ...
  • IROS 2014 – Interleaved Continuum-Rigid Manipulation A new manipulation approach, referred to as interleaved continuum-rigid manipulation, which combines inherently safe, flexible actuated segments with more precise embedded rigid-link joints is described. The redundantly actuated manipulator possesses the safety characteristics inherent in flexible segment devices while gaining some of the performance gains possible with rigid-link joint systems. A demonstration prototype was developed, the purpose of which was to explore the ...
  • Advanced Robotics 2014 – A Combined Modal-Joint Space Control of Continuum Manipulators Abstract – Continuum manipulators such as robotic tele-operated cardiac catheters continue to gain popularity for use in minimally invasive surgical procedures due to their inherent safety characteristics. However, their flexible nature makes them prone to both steady state positioning errors and undesirable vibrations. We propose a combined control  system incorporating both a tracking position controller to reduce steady state ...
  • A modeling approach for robotic catheters The soft, atraumatic construction of passive flexible catheters help reduce injury to delicate cardiac structures while providing a means of tool placement and control.  To provide kinematic and control relationships, various models of continuous catheters have been developed. However, these approaches cannot explain the nonlinear behavior of the catheter when the effect of internal friction ...
  • ICRA 2013 – Interleaved Continuum-Rigid Manipulation: An Augmented Approach For Robotic Minimally-Invasive Flexible Catheter-based Procedures In recent years, minimally-invasive surgical systems based on flexible robotic manipulators have met with success. One major advantage of the flexible manipulator approach is its superior safety characteristics as compared to rigid manipulators. However, their soft compliant structure, in combination with internal friction, results in poor position and force regulation and has limited their use to simpler surgical procedures. In this paper, ...
  • ICRA 2012 – An evaluation of closed-loop control options for continuum manipulators Abstract: Continuum manipulators are gaining widespread acceptance in commercial robotics, particularly in the medical field, where their compliance allows a large benefit for patient safety. However, this compliance also makes precise position control of these manipulators quite difficult. This paper presents two closed-loop control implementations applied to a small scale continuum manipulator. These implementations are both based on manipulator tip position ...