Medical Robot Arm Force Control for Stable 6-DOF Camera Positioning
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Solution Overview
Problem
Existing medical robot arm apparatuses struggle to provide high stability and operability for efficient medical procedures, particularly in maintaining balance and allowing for intuitive control of the arm unit and front edge unit.
Innovation Solution
A medical robot arm apparatus with a multi-link structure providing at least 6 degrees of freedom, controlled by a drive control unit that uses whole body cooperative control based on generalized inverse dynamics and ideal joint control to manage joint units and attached medical apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force control is implemented to enable soft control with excellent usability for physical interaction, then ease of operation is improved, but device complexity increases due to complicated system configuration
Solution Approach 1:
The control system is segmented into multiple independent components: a control unit that receives operation inputs, a calculation unit that computes driving forces using generalized inverse dynamics, and a drive unit that executes the control. This segmentation allows force control functionality to be added without overwhelming system complexity, as each component has a specific function.
Solution Approach 2:
The control unit acts as an intermediary between the operator's input and the robot arm's actuators. It receives operation inputs, calculates appropriate driving forces for multiple joint units using generalized inverse dynamics, and transmits these forces to the drive units. This intermediary layer simplifies the overall system architecture while enabling sophisticated force control.
2Stability of the object's composition
If a balance arm is equipped with a counter balance weight to maintain force balance during movement, then stability is improved, but device size increases
Solution Approach 1:
The patent replaces the traditional mechanical counterbalance weight system with an active force control system. Instead of using physical counterweights to balance forces, the control unit calculates and applies appropriate driving forces to each joint unit through actuators. This substitution eliminates the need for large counterbalance masses, reducing device size while maintaining stability through controlled force application.
Solution Approach 2:
The system dynamically adjusts driving forces based on real-time operation inputs and robot arm states. By changing the control parameters (driving forces) rather than relying on fixed mechanical counterbalances, the system achieves stability without requiring additional physical mass or volume in the form of counterbalance weights.
3Device complexity
If only biaxial electric driving is provided for moving the front edge unit on a plane, then device complexity is reduced, but adaptability decreases due to limited movement freedom
Solution Approach 1:
The control unit is designed to handle multiple degrees of freedom (at least 6 DOF) across multiple joint units, enabling the robot arm to perform diverse movements beyond simple biaxial plane motion. The generalized inverse dynamics calculation accommodates various operation modes including manual positioning and automated control, making the system universally adaptable to different medical procedures while maintaining a unified control architecture that doesn't excessively increase complexity.
Solution Approach 2:
The system transitions from static biaxial driving to dynamic multi-axial driving where the control unit continuously calculates and adjusts driving forces for multiple joint units based on real-time operation inputs. This dynamic control approach enables adaptable movement in three-dimensional space with at least 6 degrees of freedom, allowing the front edge unit to reach various positions and orientations while maintaining manageable system complexity through efficient force distribution across joints.
4Device complexity
If manual positioning is required for movement of the arm unit and front edge unit, then device complexity is reduced, but ease of operation deteriorates due to reduced stability and positioning accuracy
Solution Approach 1:
The control unit receives operation inputs from the operator and uses generalized inverse dynamics to calculate the appropriate driving forces for each joint unit. This feedback mechanism translates the operator's intent into precise actuator commands, providing stable and accurate positioning without requiring complex mechanical structures. The system continuously monitors operation inputs and adjusts driving forces accordingly, enhancing ease of operation while maintaining manageable device complexity.
Data Source
AI summary
Provided is a surgical imaging apparatus that includes a multi-link, multi-joint structure including a plurality of joints that interconnect a plurality of links to provide the multi-link, multi-joint structure with a plurality of degrees of freedom, at least one video camera being disposed on a distal end of the multi-link, multi-joint structure; at least one actuator that drives at least one of the plurality of joints; and circuitry that detects a joint force experienced at the at least one of the plurality of joints in response to an applied external force, and controls the at least one actuator based on the joint force so as to position the video camera.