Modular Robotic Device for Precision Surgical Bone Removal

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Solution Overview

Problem

Surgical precision bone removal procedures, especially in the lateral skull base/ear region, are invasive, time-consuming, and high-risk due to the need for precise bone drilling and milling near vital structures, requiring a balance of precision, force output, and safety that existing medical robots fail to adequately address.

Innovation Solution

A seven-degrees of freedom robotic device with a serial kinematic chain of six rotational and one translational degree of freedom, utilizing circular cross-roller bearings and linear cross-roller bearings, allowing for precise control of instruments like bone-drilling or milling tools with high rigidity and modular design for flexibility and safety, including the option to lock degrees of freedom for specific tasks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a traditional robotic arm design is used, then the device complexity is reduced, but the manufacturing precision and rigidity are insufficient for sub-50 µm precision requirements

Engineering Contradiction:

Improvepositioning precisionVSAvoidrobotic mechanism complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The robotic device is divided into modular units, each comprising a circular cross-roller bearing with integrated drive and positioning mechanisms. These standardized modules can be combined in series to achieve the required 7 degrees of freedom while maintaining high precision through uniform, repeatable manufacturing of each segment

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Traditional complex mechanical joint structures are replaced with circular cross-roller bearing mechanisms that provide precise rotational and translational motion. The cross-roller bearing design eliminates the need for complex gear trains and multiple mechanical components, achieving high rigidity and sub-50 µm precision through a simplified mechanical system

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Volume of moving object

If a compact robotic design is used, then the device size is reduced, but the working volume and adaptability are limited

Engineering Contradiction:

Improverobot sizeVSAvoidworking volume

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The modular robotic units are designed to be nested or stacked in series, with each compact module containing integrated drive mechanisms, bearings, and positioning systems. This nesting approach allows the robot to maintain a compact overall footprint while achieving a large working volume through the cumulative effect of multiple modular segments working in sequence

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The robotic system employs dynamic modular configurations where modules can be selectively activated or deactivated based on surgical requirements. The lockable joints allow the robot to switch between different degrees of freedom (6-DOF or 7-DOF modes), providing adaptability for various surgical tasks while maintaining a compact form factor

Inventive Principle:

Principle #15Dynamics

3Force

If high force output is used, then the bone drilling capability is improved, but the risk of damage to vital structures increases

Engineering Contradiction:

Improvedrilling forceVSAvoidrisk to vital structures

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

Force sensors are integrated into the circular cross-roller bearing modules to provide real-time feedback on the forces applied during bone drilling and milling. This feedback mechanism allows the control system to monitor and regulate the drilling force, ensuring it remains within safe limits and automatically adjusts to prevent damage to vital structures while maintaining adequate drilling capability

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The robotic system dynamically adjusts operational parameters including force magnitude, drilling speed, and engagement depth based on real-time conditions. By changing these parameters adaptively rather than maintaining constant high force, the system achieves effective bone removal while minimizing the risk of damaging nearby vital structures

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If a fixed-degree-of-freedom robotic design is used, then the device complexity is reduced, but the flexibility for different surgical tasks is limited

Engineering Contradiction:

Improvecontrol system complexityVSAvoidtask flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

Locking mechanisms are pre-integrated into each modular unit, allowing joints to be locked or unlocked as needed. This preliminary preparation of the mechanical structure enables the robot to be quickly reconfigured between 6-DOF and 7-DOF modes without requiring complex software reconfiguration or additional mechanical components, maintaining simplicity while providing task flexibility

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3373836B1Modular robotic device for precision surgical bone removal and other applications

Publication Date: 2023.01.04 EINDHOVEN MEDICAL ROBOTICS BV

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AI summary

Aseven-degrees of freedom modular robotic device is provided for controlling an instrument, e.g. a bone-drilling or milling device with a precision ofabout50 µm and maximum force of 50 N. The robotic device is a serial kinematic chain of six rotational degrees of freedom and one translational degree of freedom.