Medical Support Arm Gravity Compensation via Torque Sensing
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Solution Overview
Problem
Existing medical support arm apparatuses face challenges with complex configurations and increased bulkiness due to mechanical gravity compensation mechanisms, counterweights, and actuators, leading to reduced productivity, higher costs, and increased power consumption.
Innovation Solution
A medical support arm apparatus with a torque sensor and actuator in compensated joint sections, combined with a gravity compensation mechanism and encoder, allowing for precise control to cancel out load torque, enabling a more compact and lightweight configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If mechanical gravity compensation mechanisms (springs, gears, belts) are used to compensate torque, then gravitational force compensation is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical gravity compensation mechanisms (springs, gears, belts) with an actuator that uses electrical control to generate compensating torque. The actuator directly counteracts gravitational torque through motor control, eliminating the need for mechanical transmission components and significantly reducing device complexity while maintaining effective gravity compensation.
Solution Approach 2:
The patent changes the control parameter from mechanical force transmission to electrical torque control. By using an actuator with motor control, the system can dynamically adjust the compensating torque parameter to match gravitational torque requirements, achieving effective gravity compensation without fixed mechanical configurations.
2Force
If counterweights are provided on the base end side to balance the arm section, then gravitational force compensation is improved, but weight of the apparatus increases
Solution Approach 1:
The patent replaces the mechanical counterweight system with an actuator-based torque compensation system. Instead of adding physical mass to balance gravity, the actuator generates an equal and opposite torque through electrical control, achieving gravity compensation without increasing the apparatus weight.
3Force
If actuators are provided in each joint section to compensate gravitational force, then gravitational force compensation is improved, but power consumption increases
Solution Approach 1:
The patent implements selective actuator placement, providing actuators only in joint sections where gravity compensation is most critical rather than in every joint section. This partial action approach achieves sufficient gravity compensation for the arm section while minimizing the total number of actuators and reducing overall power consumption.
4Force
If mechanical gravity compensation mechanisms are used, then gravitational force compensation is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces complex mechanical gravity compensation mechanisms with an actuator-based system, which reduces manufacturing cost. The actuator system requires fewer precision-machined mechanical components (gears, belts, springs) and can be manufactured using standard actuator modules, thereby lowering production costs while maintaining effective gravity compensation functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for efficient gravity compensation with a simpler and more compact design, reducing manufacturing costs and power consumption while maintaining high precision and operability.
Implementation Method 1
an actuator provided at least in a compensated joint section that is a target of gravity compensation among the multiple joint sections, and including a torque sensor that detects a torque acting on the compensated joint section
Implementation Method 2
at least one further joint section among the multiple joint sections is located between the compensated joint section and the front end such that a length of a normal line extending from a center of rotation of the compensated joint section towards a vector indicating a direction of the gravitational force on the arm section varies non-monotonically with a rotational angle of the compensated joint section, the further joint section comprising an encoder
Implementation Method 3
a gravity compensation mechanism that imparts to the compensated joint section a compensating torque in a direction that causes the compensating torque to partly cancel out a load torque due to a self-weight of the arm section acting on the compensated joint section
Data Source
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AI summary
[Object] To make it possible to perform gravity compensation with a more compact and lightweight configuration. [Solution] There is provided a medical support arm apparatus including: an arm section including multiple joint sections, and configured such that a medical tool is provided on a front end; an actuator at least provided in a compensated joint section that is a target of gravity compensation among the joint sections, and including a torque sensor that detects a torque acting on the compensated joint section; and a gravity compensation mechanism that imparts to the compensated joint section a compensating torque in a direction that cancels out a load torque due to a self-weight of the arm section acting on the compensated joint section.