Passive preload and capstan drive for surgical instruments

Abstract

A robotic surgical system uses a passive preload system attached to a tendon that is wrapped around a capstan to control relaxed tension in the tendon. The passive preload system can employ a spring or other structure to apply tension to the tendon. The capstan can be driven by a motor when the tendon is needed to pull on a structural member of the instrument. For example, for the application of clamping pressure or movement of the structural member against resistance, capstan friction can produce the tendon tension that is many times the tension applied by the passive preload system. However, when the tendon is not needed to apply force to the member, the capstan can be freed, so that the spring system provides enough tension to prevent derailment or other malfunctions of the tendon. The low tension in relaxed tendons can reduce tendon friction, particularly in instruments with flexible shafts.

Description

technical field Background technique [0001] Automatically (as used herein, the terms "robot" or "automatic", etc. include teleoperated or teleautomated aspects) controlled instruments are known and are often used in minimally invasive medical procedures. FIG. 1 shows an example of an instrument 100 with a simplified structure to illustrate the basic working principles of some current automatically controlled medical instruments. Instrument 100 includes a tool or end effector 110 at the distal end of shaft 120 . The proximal end of the shaft 120 is connected to a transmission or drive mechanism 130 , which is sometimes referred to as a rear end mechanism 130 . During a medical procedure, the distal end of the end effector 110 and shaft 120 can be inserted through a small incision or autologous orifice in the patient to position the end effector 110 at the surgical site of the patient. The end effector 100 as shown includes jaws 112 and 114 that may be used at a surgical sit...

AI Technical Summary

Problems solved by technology

In all of the above cases, the increased friction quickly makes it difficult to precisely control the motion of the end effector 110 and can lead to imprecise manipulation of, for example, tissue, sutures, needles during surgery.

Furthermore, preloading the tendon of a medical device with proper tension can add to the complexity of the medical device manufacturing process

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