Surgical Robot Hinge Axis Force Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current robot structures for minimally invasive surgery face challenges in accurately measuring grasping and contact forces due to superimposition of driving forces, limited installation space for sensors, and the limitations of cable pulls and hydraulic components, which affect precision and sterilizability.
Innovation Solution
A robot structure with a hinge axis supported by a orthogonal arrangement of driving elements and sensor elements, where the driving forces are canceled out at the hinge axis, allowing precise measurement of grasping and contact forces without interfering with the sensor readings, and utilizing a simple mechanical design for sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force transmission means are used to actuate the movable robot element, then the robot structure can be actuated, but the driving forces superimpose the contact forces and deteriorate measurement precision
Solution Approach 1:
The force transmission system is segmented into separate components: a force transmission means for actuation and a sensor element for measurement. The sensor element is positioned to measure forces at a location separate from the force transmission path, allowing independent optimization of actuation and measurement functions without interference between them.
Solution Approach 2:
The sensor element acts as an intermediary measurement device that indirectly measures contact forces without being directly influenced by the driving forces from the force transmission means. The sensor is positioned to detect forces transmitted through the robot element structure, separating the measurement function from the actuation function.
2Measurement precision
If sensor elements are integrated into the grasping jaws, then force measurement is possible, but the installation space is insufficient due to minimally invasive requirements
Solution Approach 1:
Instead of integrating sensors directly into the grasping jaws (three-dimensional integration), the sensor element is positioned in a different spatial location - on the robot element structure away from the grasping jaws. This dimensional relocation allows the sensor to measure forces transmitted through the structure without occupying valuable space within the grasping jaw assembly.
3Ease of operation
If Bowden cables are used for force transmission, then the robot can be actuated, but the sleeve expansion and shortening induce undesirable driving forces that superimpose contact forces
Solution Approach 1:
The problematic Bowden cable sleeve is extracted from the direct force transmission path to the sensor measurement location. The force transmission means is repositioned or redesigned so that its actuation forces do not directly superimpose on the sensor element, separating the actuation function from the measurement function spatially or mechanically.
4Ease of operation
If cable pulls are used for driving forces, then the robot can be actuated, but the friction and losses increase and sterilization becomes limited
Solution Approach 1:
The cable pull mechanical system is replaced or supplemented with alternative actuation mechanisms that are more suitable for minimally invasive surgery. The force transmission means is designed to be compatible with sterilization processes, potentially using materials or configurations that allow autoclaving or other sterilization methods, improving reliability for surgical applications.
Data Source
AI summary
A robot structure, in particular for minimally invasive surgery, is provided with a first robot element and a second robot element that can be moved relative to the first robot element, said second robot element having two grasping and/or cutting elements which can be uniformly moved with respect to each other and which are connected to the first robot element via a hinge axis. The robot structure further has a force transmitting device for moving the grasping and/or cutting elements of the movable robot element and at least one sensor element comprising a sensitive end for receiving forces and/or torques that occur on the movable robot element and includes a base element that is fixed to the first robot element.