Control of Teleoperation Systems for Beating-Heart Surgery

• Author / Creator

  Cheng, Lingbo

• Cardiovascular disease is one of the leading causes of death worldwide. Conventional extra- and intra-cardiac surgeries need the heart to be arrested and involve connecting the patient to a cardiopulmonary bypass (CPB) machine. However, arrested-heart surgery has adverse effects such as the risk of long-term cognitive loss and stroke. Different from arrested-heart surgery, beating-heart surgery could eliminate such negative effects of CPB by allowing the heart to beat normally and could also enable intraoperative evaluation of the heart tissue motion, which is critical to the assessment of reconstructive heart operations. Beating-heart surgery, however, introduces serious challenges for the surgeons due to the heart’s fast motions. To facilitate beating-heart surgery, minimize the risks of tool-tissue collision and tissue injury, and ensure haptic feedback to the surgeon precludes oscillatory tool-tissue interaction forces, a robot-assisted system is necessary for beating-heart surgery. If the robot-assisted system can move a surgical tool in synchrony with the target heart tissue while the heart beats freely, the oscillatory forces between the surgical tool and heart tissue will be small, giving a feeling of making contact with an idle heart to the human operator (surgeon).
  This thesis presents a study of robot-assisted master-slave teleoperation systems for beating-heart surgery. The objective is to develop a telerobotic system to simultaneously compensate for the beating heart’s motion and provide the human operator with non-oscillatory force feedback, which will give him/her a feeling of operating on an “arrested” heart. To this end, in Chapter 3, a bilateral-impedance-controlled telerobotic system is proposed to help perform surgical tasks without stopping the heart by designing two reference impedance models for the master and slave robots. The efficacy of the proposed teleoperation system is assessed through experiments for 1-DOF (degree of freedom) and 3-DOF heart motions, respectively.
  Inspired by the bilateral impedance control method, a switched-impedance control method is proposed and implemented for telerobotic beating-heart surgery in Chapter 4. This method involves two switched reference impedance models for the master and slave robots to achieve both motion compensation and non-oscillatory force feedback during slave-heart interaction. Both the switched reference impedance models and their parameters are different from the previous method. The main advantage of this method over the one presented in Chapter 3 is that during slave-heart interaction, the human operator can feel the stiffness of the heart tissue through the master robot.
  In Chapters 5 and 6, the robot impedance control method is then combined with ultrasound imaging-based control algorithms to achieve the ideal behaviors. Similarly, to provide the human operator with non-oscillatory force feedback, a reference impedance model is designed for the master robot. Moreover, the synchronization of the slave robot with heart motion is attained by employing ultrasound imaging to measure the heart tissue position. Issues including slow sampling rate and time delay caused by ultrasound imaging are addressed by a cubic polynomial interpolation and a heart motion predictor, respectively. Additionally, two heart motion predictors: the extended Kalman filter (EKF) in Chapter 5 and the recurrent neural network (NN) predictor in Chapter 6 are designed. The ability of the systems with two heart motion predictors is evaluated experimentally. It is demonstrated that the motion compensation and force feedback using a NN predictor performs better than using an EKF predictor for a teleoperation system in beating-heart surgery.
  In Chapter 7, the impedance control method is used for haptic-enabled surgical training and cooperation in beating-heart surgery. A multi-user shared control architecture is developed, and a multilateral impedance-controlled strategy is employed for this architecture. The desired objectives of the proposed system are a) providing position guidance to the trainees during training procedure, b) providing force feedback to all human operators (trainer and trainees) regardless of their levels of authority over the slave robot, c) motion compensation for the heart’s motion, and d) reflecting only the non-oscillatory force portion of the slave-heart tissue interaction force to all human operators. To this end, virtual fixtures and a dominance factor are introduced, and a reference impedance model with adjusted parameters is designed for each master or slave robot. The proposed impedance-based control methodology is evaluated experimentally, and its feasibility is demonstrated successfully.

• Subjects / Keywords

  • Beating-heart surgery
  • Teleoperation
  • Medical robotics
  • Robot-assisted surgery

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-4gm0-7824

• License

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