Friction compensation in a minimally invasive surgical apparatus

#The present invention is generally related to improved robotic devices and methods, particularly for telesurgery.

#Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue which is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. Many surgeries are performed each year in the United States. A significant amount of these surgeries can potentially be performed in a minimally invasive manner. However, only a relatively small percentage of surgeries currently use these techniques due to limitations in minimally invasive surgical instruments and techniques and the additional surgical training required to master them.

#Advances in minimally invasive surgical technology could dramatically increase the number of surgeries performed in a minimally invasive manner. The average length of a hospital stay for a standard surgery is significantly longer than the average length for the equivalent surgery performed in a minimally invasive surgical manner. Thus, the complete adoption of minimally invasive techniques could save millions of hospital days, and consequently millions of dollars annually in hospital residency costs alone. Patient recovery times, patient discomfort, surgical side effects, and time away from work are also reduced with minimally invasive surgery.

#The invention will now be described, by way of example, and with reference to the accompanying diagrammatic drawings, in which:

#FIG. 1A shows a three-dimensional view of a control station of a telesurgical system in accordance with the invention;

#FIG. 1B shows a three-dimensional view of a cart or trolley of the telesurgical system, the cart carrying three robotically controlled arms, the movement of the arms being remotely controllable from the control station shown in FIG. 1A;

#This application is related to the following patents and patent applications, the full disclosures of which are incorporated herein by reference: PCT International Application No. PCT/US98/19508, entitled “Robotic Apparatus”, filed on Sep. 18, 1998; U.S. Application Serial No. 60/111,713, entitled “Surgical Robotic Tools, Data Architecture, and Use”, filed on Dec. 8, 1998; U.S. Application Serial No. 60/111,711, entitled “Image Shifting for a Telerobotic System”, filed on Dec. 8, 1998; U.S. Application Serial No. 60/111,714, entitled “Stereo Viewer System for Use in Telerobotic System”, filed on Dec. 8, 1998; U.S. Application Serial No. 60/111,710, entitled “Master Having Redundant Degrees of Freedom”, filed Dec. 8, 1998; and U.S. Pat. No. 5,808,665, entitled “Endoscopic Surgical Instrument and Method for Use”, issued on Sep. 15, 1998; the full disclosures of which are incorporated herein by reference.

#It is to be appreciated that although the method and control system of the invention is described with reference to a minimally invasive surgical apparatus in this specification, the application of the invention is not to be limited to this apparatus only, but can be used in any type of apparatus requiring friction compensation. Thus, the invention may find application in the fields of satellite dish tracking, handling hazardous substances, to name but two of many possible qualifying fields in which precisional movement is required. In some cases, it may be required to compensate for friction on a single part of a system such as on a master controller only.

#Referring to FIG. 1A of the drawings, a control station of a minimally invasive telesurgical system is generally indicated by reference numeral 200. The control station 200 includes a viewer 202 where an image of a surgical site is displayed in use. A support 204 is provided on which an operator, typically a surgeon, can rest his forearms while gripping two master controls (not shown in FIG. 1A), one in each hand. The master controls are positioned in a space 206 inwardly beyond the support 204. When using the control station 200, the surgeon typically sits in a chair in front of the control station 200, positions his eyes in front of the viewer 202 and grips the master controls one in each hand while resting his forearms on the support 204.