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LaproYaw

A special mechanism

The unique feature of a pulley steering mechanism compared to other mechanisms, is the tight bend. Additionally, in this system, the hinge of the end-effector contribute to the articulation of the tip. The jaw parts are actuated by two cable-loops.

A two-faced challenge

The first challenge in designing such a system is that each cable-loop is related to both a pitch and yaw movement. In a robotic system this is compensated by software. In a purely mechanical system, the mechanism itself has to compensate, in order to design a usable instrument.
The second challenge is that because large forces are required, steel cables are used having a minimal thickness. If the pulleys are too small steel cables will start to fray after a few movements. For this reason, the instruments in robotic systems have a diameter of 8 mm1, which is larger than the common diameters of laparoscopic instruments (5mm).

Figure 1: The hinged, steerable tip of the LaproYaw
Figure 1: The hinged, steerable tip of the LaproYaw

Dr. Ir. Jules Scheltes, CTO DEAM: 

“It was a challenging mechanism. And seeing it realised in a series of prototypes gave joy to my engineering heart.”

Figure 2: LaproYaws used to suture during an minimally invasive procedure
Figure 2: LaproYaws used to suture during an minimally invasive procedure

Being a company focusing on steerable devices for minimally invasive procedures, our designers investigate multiple options for steering instruments. This project had its main goal increase DEAM’s know-how on steering mechanism. A 5 mm pulley jaw mechanism actuated by a purely mechanical handheld mechanism was designed, prototyped and tested. Figure 1 shows the prototype orienting during a suturing exercise. Figure 2 presents an impression of how the rugged steerable technology could be applied.


References:
[1] Da Vinci X/Xi Instrument & Accessory Catalog, November 2020

October 30, 2020