# How a Surgical Robot Arm's Wrist Moves Instruments > This patent describes a specific design for the end part of a surgical robot arm, called the terminal portion, which uses a clever arrangement of three joints to precisely position and rotate surgical tools. - **Patent:** US 12414825 - **Original title:** Surgical arm - **Owner:** CMR Surgical - **Granted:** 2025 - **Status:** Active - **Times cited:** 0 - **Field:** medical_devices, robotics, software, mechanical ## What it does The patent describes a specialized "terminal portion" for a surgical robot arm, which is like the robot's wrist. This portion has three main parts: a "distal segment" that holds the surgical tool, an "intermediate segment" in the middle, and a "basal segment" that connects to the rest of the arm (Claim 1). It uses three articulations, or joints, to move the tool. A "first articulation" lets the tool rotate around its own axis (the "first axis") relative to the intermediate segment. A "second articulation" lets the intermediate segment rotate relative to the basal segment around a "second axis." The "intermediate segment" itself contains a "third articulation" that allows the distal segment and the tool to rotate about "third and fourth axes" (Claim 1). The clever part is how these joints are arranged: in a straight position, the first and second axes line up, and the third and fourth axes cross each other and are perpendicular to the first axis (Claim 1). This allows the robot to precisely control the instrument's position and orientation. For example, a surgeon could use this arm to precisely rotate a scalpel while also angling it for a delicate cut, all through the coordinated movement of these three joints. ## What it does NOT cover - Robot arms where the surgical instrument is not detachably attached to a single connector on the distal segment. - Surgical robot arms that do not have the specific arrangement of first, second, and third articulations as defined in Claim 1, especially regarding the collinearity and transverseness of the axes in a straight configuration. - Robot arms where the intermediate segment does not contain a third articulation that allows rotation about third and fourth axes. - Surgical robot arms where the connector for the instrument can articulate relative to the basal segment using more than just the first, second, and third articulations. - Robot arms where the first and second axes are not collinear in a straight configuration of the terminal portion. ## The clever bit The novelty lies in the specific kinematic arrangement of the three articulations within the terminal portion, particularly how the first, second, third, and fourth axes are configured to be collinear and transverse in a straight configuration. This allows for a compact and highly dexterous "wrist" mechanism for surgical instruments. ## Real-world examples 1. CMR Surgical Versius surgical robot system 2. Intuitive Surgical da Vinci surgical system 3. Medtronic Hugo RAS system 4. Minimally invasive surgical robots ## Why it matters Precise control over surgical instruments is critical for minimally invasive surgery, where surgeons operate through small incisions. This patent aims to improve the dexterity and range of motion of robotic surgical arms, potentially allowing for more complex procedures to be performed robotically. Better articulation in the robot's "wrist" can reduce the need for larger incisions or more complex movements of the entire robot arm, leading to better patient outcomes. ## Frequently asked questions ### What does How a Surgical Robot Arm's Wrist Moves Instruments cover? This patent describes a specific design for the end part of a surgical robot arm, called the terminal portion, which uses a clever arrangement of three joints to precisely position and rotate surgical tools. ### Who owns patent US 12414825? CMR Surgical owns this patent, granted in 2025. ### When does this patent expire? This patent is expected to expire on December 6, 2041, when the invention enters the public domain. ### What problem does this patent solve? Precise control over surgical instruments is critical for minimally invasive surgery, where surgeons operate through small incisions. This patent aims to improve the dexterity and range of motion of robotic surgical arms, potentially allowing for more complex procedures to be performed robotically. Better articulation in the robot's "wrist" can reduce the need for larger incisions or more complex movements of the entire robot arm, leading to better patient outcomes. ### What does this patent NOT cover? Robot arms where the surgical instrument is not detachably attached to a single connector on the distal segment. **Full plain-English explainer:** https://patentbrief.org/patent/us/12414825/surgical-arm **Original patent:** https://patents.google.com/patent/US12414825 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How a Robotic Surgical Tool Clamps Tissue Manually and Automatically](https://patentbrief.org/patent/us/11786761/ultrasonic-robotic-tool-actuation) — This patent describes a surgical tool for robotic operations that can clamp tissue using a motor-driven yoke, but also allows a surgeon to manually control the clamping action. - [How Spacecraft Servicing Pods Maneuver and Refuel Other Satellites](https://patentbrief.org/patent/us/11685554/starship-upper-stage) — A specialized robotic pod designed to dock with aging satellites and use a flexible, multi-jointed boom arm to adjust their orbit or velocity. - [How the Apple Watch Uses the Digital Crown to Flip Objects](https://patentbrief.org/patent/us/10275117/apple-watch-heart-rate-sensor) — A method for rotating virtual objects on a small wearable screen by spinning the physical dial on the side of the device based on how fast you turn it. - [How to Create Wide-Field Images of Tissue Using OCT Scanners](https://patentbrief.org/patent/us/9677869/autonomous-spaceport-drone-ship-asds) — A method for stitching together multiple high-resolution medical images of uneven tissue samples to create a single, wide-field view for better diagnostic clarity. - [Catheter System for Opening and Closing Body Passages](https://patentbrief.org/patent/us/4195637/balloon-angioplasty-catheter-gruentzig) — This 1980 patent describes a medical catheter system with a guide catheter and a special dilatation catheter that can expand to open or close body passages, like blood vessels.