Manipulator Arm Null-Space Control for Collision Avoidance
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Solution Overview
Problem
Robotic surgical manipulators face challenges in avoiding collisions between adjacent arms during minimally invasive procedures, particularly when moving through large angular ranges, which can lead to undesirable contact with other manipulators, surgical personnel, or the patient's surface, and require complex setup configurations.
Innovation Solution
The implementation of highly configurable surgical robotic manipulators with more degrees of freedom than the associated surgical end effectors, utilizing a processor to determine reference geometries, calculate avoidance movements within the null-space of the Jacobian, and drive joints to maintain desired separation and end effector states, thereby preventing collisions while increasing the range of motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If robotic manipulator arms are moved through large angular ranges to increase range of motion, then the range of motion is improved, but the risk of collision between manipulator arms increases
Solution Approach 1:
The system dynamically adjusts manipulator configurations in real-time by calculating avoidance movements within the null-space of the Jacobian matrix. This allows the manipulators to adapt their joint positions dynamically during operation to prevent collisions while maintaining end effector positions, resolving the contradiction between large angular ranges and collision risk.
Solution Approach 2:
The system changes the parameter space by utilizing the null-space degrees of freedom of the manipulator joints. By transforming the problem from Cartesian space collision avoidance to joint space parameter optimization, the system can achieve collision avoidance through parameter adjustments without compromising the end effector's operational range.
2Reliability
If highly configurable manipulators with additional degrees of freedom are used to avoid collisions, then collision avoidance capability is improved, but device complexity increases
Solution Approach 1:
The system replaces physical mechanical constraints with computational algorithms. Instead of adding physical barriers or complex mechanical restraint mechanisms, the invention uses software-based control that calculates and executes avoidance movements through the null-space of the Jacobian matrix, achieving collision avoidance without increasing physical device complexity.
Solution Approach 2:
The null-space calculation acts as an intermediary between the desired end effector motion and the actual manipulator joint movements. This computational intermediary transforms collision avoidance requirements into appropriate joint space commands, enabling sophisticated collision prevention without requiring complex physical modifications to the manipulator structure.
3Reliability
If mechanically constrained remote-center linkages are used to restrain pivotal motion, then safety is improved, but setup complexity and difficulty of manual configuration increases
Solution Approach 1:
The system provides self-service by automatically calculating and executing avoidance movements without requiring manual setup or configuration. The real-time null-space computation and automated joint position adjustment eliminate the need for operators to manually configure complex mechanical restraint systems, making the system easier to operate while maintaining safety.
Data Source
Figure 1A
Figure 1B
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AI summary
Devices, systems, and methods for avoiding collisions between manipulator arms using a null-space are provided. In one aspect, the system calculates an avoidance movement using a relationship between reference geometries of the multiple manipulators to maintain separation between reference geometries. In certain embodiments, the system determines a relative state between adjacent reference geometries, determines an avoidance vector between reference geometries, and calculates an avoidance movement of one or more manipulators within a null-space of the Jacobian based on the relative state and avoidance vector. The joints may be driven according to the calculated avoidance movement while maintaining a desired state of the end effector or a remote center location about which an instrument shaft pivots and may be concurrently driven according to an end effector displacing movement within a null-perpendicular-space of the Jacobian so as to effect a desired movement of the end effector or remote center.