The manipulation of fast-moving, delicate tissues in beating heart procedures presents a considerable challenge to the surgeon. A robotic force tracking system can assist the surgeon by applying precise contact forces to the beating heart during surgical manipulation. Standard force control approaches cannot safely attain the required bandwidth for this application due to vibratory modes within the robot structure. These vibrations are a limitation even for single degree-of-freedom systems that drive long surgical instruments. These bandwidth limitations can be overcome by the incorporation of feed-forward motion terms in the control law. For intracardiac procedures, the required motion estimates can be derived from 3-D ultrasound imaging. Dynamic analysis shows that a force controller with feed-forward motion terms can provide safe and accurate force tracking for contact with structures within the beating heart. In vivo validation confirms that this approach confers a 50% reduction in force fluctuations when compared with a standard force controller and a 75% reduction in fluctuations when compared with manual attempts to maintain the same force.

The use of 3D ultrasound imaging for both imaging and tracking has enabled minimally-invasive, beating heart intracardiac procedures. However, the rapid movements of internal heart structures pose a serious challenge to the surgeon that is compounded by the presence of significant time delays in 3D ultrasound imaging. This paper investigates the concept of using a one-degree-of-freedom motion compensation system to synchronize instruments with tissue motions that are approximately one-dimensional. We first describe the motion of the mitral valve, which is well approximated by a 1D model. The subsequent development of a motion compensation system is described, which comprises a motion compensation instrument as well as an extended Kalman filter that can compensate for system delays. The benefits and robustness of the resulting system are demonstrated in user trials under tracking conditions with measurement noise, delay, and heart rate variability.

Beating heart procedures promise significant health benefits to patients but the fast motion of the heart poses a serious challenge to the surgeon. Robotic motion synchronization to heart movements could facilitate these surgeries, although for intracardiac procedures this requires the development of a predictive filter to compensate for the measurement noise and time delay present in 3D ultrasound imaging. In this paper, we present a quasiperiodic cardiac motion model and apply the extended Kalman filter to estimation of its parameters in real-time. We experimentally demonstrate high accuracy robot tracking to heart motion using this filter.