Support Arm Device Reducing Motor Output via Segmented Drive
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Solution Overview
Problem
Existing support arm devices for surgical robots using parallel links require high motor output due to the need to revolve relatively heavy components, including counterweights, which increases the burden on motors and complicates their design.
Innovation Solution
A support arm device with a configuration that includes a first drive part and a second drive part fixed to a base part, using at least one parallel link to support a tool, allowing the tool to perform rotational motions by reducing the output required from the motors through a specific arrangement of drive shafts and links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If one motor is fixed to the base part and causes a movable part with counterweight to revolve, then the arm part can be maintained in a self-standing state, but the motor output becomes excessively large due to the heavy load
Solution Approach 1:
The drive system is segmented into multiple independent motors (first motor and second motor) that work together. Instead of one motor bearing the entire load of revolving the movable part with counterweight, the segmentation allows the arm part's weight to be supported independently while the motors focus on generating rotational motion, thereby reducing the power burden on each motor
Solution Approach 2:
The conventional approach is inverted by fixing both motors to the base part rather than placing one motor in the movable part. This inversion allows the motors to remain stationary and only the arm part to move, reducing the motor output requirement while maintaining the self-standing capability through the parallel link structure
2Adaptability or versatility
If three motors are used to deform the parallelogram structure for pivotal motions around RCM, then the arm part can achieve the required motion, but the device complexity and cost increase
Solution Approach 1:
The first motor and second motor are designed to perform multiple functions simultaneously. The first motor causes the arm part to revolve around a first axis, while the second motor causes it to revolve around a second axis. This multi-functionality allows the system to achieve complex pivotal motions around the RCM with fewer motors, reducing device complexity while maintaining versatility
Solution Approach 2:
The third motor from the conventional three-motor system is extracted and its function is integrated into the coordinated operation of the first and second motors. By taking out the redundant motor and redistributing its functional requirements to the remaining motors, the system achieves the same pivotal motion capability with reduced complexity
3Ease of operation
If motors are disposed on the tip side of the arm part, then the control is direct, but the motor weight imposes a burden on the output and increases the weight of the moving object
Solution Approach 1:
The motor placement is inverted from the tip side to the base part. Instead of having motors on the moving tip side which would add to the moving weight, both motors are fixed to the stationary base part. This inversion eliminates the motor weight burden from the moving object while the parallel link mechanism transmits the rotational motion to achieve direct control of the arm part
Data Source
AI summary
A support arm device includes a first drive part that is fixed to a base part and cause a first drive shaft to perform shaft rotation, a second drive part that is fixed to the base part and cause a second drive shaft to perform shaft rotation, and an arm part including at least one parallel link and that supports a predetermined tool. The arm part is caused to change an attitude to cause the predetermined tool to perform a predetermined rotational motion by the first drive part and the second drive part being driven.