Current open-heart procedures requiring the use of a medial sternotomy and a heart-lung machine can potentially be performed by entering the heart through the cardiac wall. A new procedure in cardiac surgery involves introducing an ablation tool through the appendage of the left atrium. This method, intended for the treatment of atrial fibrillation, septal defect repair and valve replacement, provides increased control over the ablating instrument [1]. It is believed that this procedure will ultimately be performed under robotic control and image-guidance provided by intra-cardiac ultrasound. However, the intra-cardiac guidance presents several drawbacks, such as limited field of view, temporary loss of signal, and, in some cases, difficulty with interpreting the signal. We believe that the introduction of haptic feedback into this environment will enhance the procedure by providing tactile cues to assist in the location of the surgical targets. Keywords. Artificial potential fields, haptic feedback, sigmoid functions.