Link Mechanism Stiffness Adjustment via Slider Positioning
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Solution Overview
Problem
Existing link mechanisms for robots struggle to change the stiffness of a joint in response to external forces due to the limitations of transmitting driving force through a speed reducer, requiring a separate transmission actuator and resulting in delayed responses to external circumstances.
Innovation Solution
A link mechanism with a pivot bar, slider, and elastic member, along with an A and B link system and actuators, allows for adjustable stiffness by changing the position of the slider, eliminating the need for a dedicated stiffness adjustment actuator and enabling simpler configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a speed reducer is used to transmit driving force from the electric actuator to the joint, then the driving force can be amplified, but the stiffness of the joint cannot be changed and the response to external forces is delayed
Solution Approach 1:
The mechanism is divided into two independent systems: the A link system for position control and the B link system for stiffness control. This segmentation allows each system to perform its specific function without interfering with the other, enabling both force transmission and stiffness adjustment capabilities.
Solution Approach 2:
The single electric actuator performs dual functions by controlling both the A link system (for position control) and the B link system (for stiffness control). This multi-functionality eliminates the need for a separate transmission actuator while maintaining both driving force transmission and stiffness adjustability.
2Adaptability or versatility
If a transmission actuator is added to change the stiffness of the joint, then the stiffness can be adjusted, but the device complexity increases and the response is still delayed
Solution Approach 1:
The single electric actuator is designed to control both the A link system and B link system through a unified control unit. This multi-functional design eliminates the need for additional transmission actuators, reducing device complexity while maintaining stiffness adjustability.
Solution Approach 2:
The B link system dynamically adjusts the stiffness of the joint by changing the position of the slider on the pivot bar. This dynamic adjustment capability allows the joint stiffness to be changed in response to external circumstances without adding complex mechanical transmission components.
3Adaptability or versatility
If the slider position on the pivot bar is changed, then the stiffness of the joint can be adjusted, but a mechanism is needed to move the slider
Solution Approach 1:
The electric actuator controls both the A link system and B link system, and the B link system's movement of the slider serves dual purposes: it adjusts stiffness while also being controlled by the same actuator that provides driving force. This eliminates the need for a separate mechanism dedicated solely to slider movement.
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
Enables easy adjustment of joint stiffness by changing the slider's position, reducing the need for additional actuators and allowing for lighter, more efficient mechanisms with improved responsiveness to external forces.
Implementation Method 1
an elastic member which is connected to the pivot bar and the second main link to urge the pivot bar toward a neutral position
Data Source
AI summary
A link mechanism (10) has a first main link (11) and a second main link (21), which are coupled by a joint (31). The link mechanism (10) includes: a pivot bar (41) which has one end pivotably attached at a position in the second main link (21), the position opposing the joint (31), along a plane that is orthogonal to a rotating shaft of the joint (31), and which extends toward the joint (31) from the one end; a slider (42) provided on the pivot bar (41) slidably along the pivot bar (41); a moving mechanism (50) which has one end coupled to the joint (31) and the other end coupled to the slider (42) to move the slider (42); and elastic members (43) which are connected to the pivot bar (41) and the second main link (21) to urge the pivot bar (41) toward a neutral position.