When performing robot-assisted laparoscopic surgery, surgeons use sensors to verify that a cannula or trocar of the correct length and diameter has been loaded in the robotic member before insertion into the body cavity.


  • No mechanical contacts
  • Improved confidence and safety
  • Ease of integration into robotic system
  • Detection through a barrier


  • Extended operating distance
  • Small size


To perform robot-assisted laparoscopic surgery, the surgeon sits at a computer console viewing a 3-D image of the surgical field and guiding surgical instruments via joy-sticks. The improved depth perception and rotational movement provided by a robot has extended laparoscopic surgery to more complex procedures. These require cannulas of many different types, each individually identified by ridges and grooves machined into the area clamped by the robotic member.

If the wrong cannula type is fitted it may be too small for the tools required or too large for the intended procedure, with potential harm to surgical outcomes. It is therefore essential that the robotic system should check the cannula before allowing the surgeon to proceed with surgery.

A non-contact solution is required. Space constraints around the robot also make small size essential.


Basic range inductive sensors from the Classics family (series 600), optimized for increased operating distance, are installed into the clamping block of the robotic member to detect the presence or absence of machined ridges and grooves in the cannula. The result is a binary code that identifies the specific dimensions and profile of the cannula loaded. This detection is accomplished through the wall of the mounting block, isolating the sensors from the surgical device. Due to space constraints, these 6.5 mm diameter sensors are mounted side by side with no spacing, essentially violating mounting rules. To avoid the possibility of cross talk or mutual interference the sensors are powered on and off sequentially and their output status monitored.

Sensor data delivered to the control system allows the surgeon to proceed with confidence: instrument movements within the patient’s body will be dimensionally correct and the internal size of the cannula is sufficient for entry of the surgical tools required.