Compact Surgical Wrist Mechanism for Torque Through-Angle Transmission
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Solution Overview
Problem
Existing minimally invasive surgical tools face challenges in transmitting desired torques and forces across compact articulated wrists, lacking the ability to mimic the natural action of a surgeon's wrist, which affects the effectiveness and precision of telesurgical tasks.
Innovation Solution
A two degree-of-freedom wrist mechanism is introduced, comprising an intermediate wrist member pivotally coupled with an instrument shaft and an end effector body, allowing for two-dimensional reorientation of the end effector, and incorporating linked tension members and mechanisms for transmitting torque through angles, ensuring smooth and reliable articulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact articulated wrist is used in minimally invasive surgical tools, then the tool can access confined body spaces, but the ability to transmit desired torques and forces is compromised
Solution Approach 1:
The wrist mechanism is divided into multiple segments including an instrument shaft, intermediate wrist member, and end effector body, each capable of independent rotation about specific axes. This segmentation allows the distribution of mechanical loads across multiple joints and members, enabling effective torque transmission despite the compact overall size of the wrist assembly.
2Ease of operation
If a two degree-of-freedom wrist mechanism is introduced, then the maneuverability and natural wrist action are improved, but the device complexity increases
Solution Approach 1:
The intermediate wrist member serves multiple functions: it acts as a structural connector between the instrument shaft and end effector body, provides rotation about the second axis for wrist articulation, and serves as a mounting platform for the actuation mechanism. This multi-functionality reduces the need for separate components, thereby managing complexity while achieving two-degree-of-freedom maneuverability.
3Adaptability or versatility
If the end effector is reoriented in two dimensions, then the access and visibility in confined spaces are improved, but the control cable tension management becomes more challenging
Solution Approach 1:
The intermediate wrist member acts as an intermediary that decouples the complex cable routing from the end effector articulation. By providing a dedicated rotation axis and mounting interface, it simplifies the cable path management while enabling two-dimensional end effector reorientation, thus managing cable tension control complexity.
Data Source
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AI summary
Surgical tools having a two degree-of-freedom wrist (70), wrist articulation by linked tension members (218, 220, 222, 224), mechanisms (372, 390) for transmitting torque through an angle, and minimally invasive surgical tools incorporating these features are disclosed. An elongate intermediate wrist member (80) is pivotally coupled with a distal end of an instrument shaft (74) so as to rotate about a first axis transverse to the shaft, and an end effector body (72) is pivotally coupled with the intermediate member so as to rotate about a second axis that is transverse to the first axis. Linked tension members (218, 220, 222, 224) interact with attachment features (180, 182, 184, 186) to articulate the wrist. A torque-transmitting mechanism (372, 390) includes a coupling member (384, 394), coupling pins (398, 400), a drive shaft (392), and a driven shaft (396). The drive shaft is coupled with the driven shaft so as to control the relative orientations of the drive shaft, the coupling member, and the driven shaft.