Legged Robot Foot Shock Absorber Stroke Conversion
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Solution Overview
Problem
Existing leg type mobile robots face challenges in achieving high locomotive stability due to insufficient shock absorption during landing and reduced longevity of elastic members, particularly when moving at high speeds, as the small stroke of compression in rubber-based shock absorbers is inadequate for absorbing high-frequency shocks and maintaining reaction force during bracing periods.
Innovation Solution
A leg type mobile robot design incorporating a foot structure with a shock absorber and motion direction conversion mechanism, such as a bell crank or four-bar linkage, which increases the stroke of the shock absorber nonlinearly, allowing for a small reaction force during landing and a high reaction force during bracing, enhancing locomotive stability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a rubber-based elastic member is used for shock absorption, then the structure is simple, but the stroke of compression is small and cannot fully absorb high-frequency shocks during landing
Solution Approach 1:
The foot structure is segmented into multiple functional components: a foot sole plate, a movable portion, and a shock-absorbing device with elastic members. This segmentation allows each component to perform its specific function optimally, with the elastic members providing substantial stroke for shock absorption while the overall structure remains manageable.
Solution Approach 2:
The shock-absorbing device introduces a new dimension of motion by allowing the movable portion to move not only vertically but also in horizontal directions relative to the foot sole plate. This multi-directional movement capability increases the effective stroke for shock absorption beyond what a simple vertical compression mechanism could achieve.
2Stability of the object's composition
If the elastic member is compressed to produce sufficient reaction force during bracing period, then locomotive stability is improved, but the longevity of the elastic member is reduced
Solution Approach 1:
The shock-absorbing device employs multiple elastic members arranged to provide dynamic response characteristics. The members work together to distribute and modulate the reaction force, providing sufficient stability during bracing while reducing peak compression stresses on individual members, thereby extending their service life.
Solution Approach 2:
The device changes the parameters of shock absorption by using multiple elastic members with specific arrangement and characteristics. This configuration allows the system to provide high reaction force when needed for stability while distributing the mechanical stress to prevent premature fatigue failure of the elastic members.
3Reliability
If the reaction force during landing is made small, then shock absorption is improved, but the reaction force during bracing period becomes insufficient for high-speed locomotion stability
Solution Approach 1:
The shock-absorbing device is designed to provide different levels of reaction force during different phases of the locomotion cycle. During landing, the device allows greater compression with softer response to absorb shock, while during the bracing period, the pre-compressed elastic members provide the necessary rigid reaction force for stable high-speed locomotion.
Solution Approach 2:
The dynamic characteristics of the shock-absorbing device allow it to adapt its stiffness and reaction force characteristics based on the phase of locomotion. The multiple elastic members are arranged to provide progressive resistance, being softer during initial contact for shock absorption and stiffer during the bracing phase for stability.
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 design effectively absorbs shocks during landing with a small reaction force while ensuring high locomotive stability during bracing, improving the robot's ability to maintain speed and extend the lifespan of components by increasing the stroke of the shock absorber beyond conventional rubber-based systems.
Implementation Method 1
a spring mechanism provided with an elastic member (rubber bushing) having an impact absorbing function
Implementation Method 2
the elastic member compresses in a direction perpendicular to the ground contact surface of the foot when it absorbs a shock
Implementation Method 3
a motion direction conversion mechanism joined swingably to the second end portion of the shock absorber and to a second point of the movable portion, respectively, and configured to convert a motion of the movable portion in the first direction to a motion of the second end portion of the shock absorber in the second direction
Data Source
AI summary
A leg type mobile robot includes a foot joined to a distal end of a leg through a second joint. The foot includes a foot flat portion having a ground contact end of the foot, a movable portion joined to the second joint and configured to be movable in a first direction with respect to the foot flat portion, a shock absorber comprising first and second end portions allowed to move closer to or away from each other in a second direction, the first end portion of the shock absorber being joined to a first point of the movable portion, and a motion direction conversion mechanism configured to convert a motion of the movable portion in the first direction to a motion of the second end portion of the shock absorber in the second direction with respect to the first point of the movable portion.