Segmented Robot Foot Assembly for Low-Impact Locomotion
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Solution Overview
Problem
Legged robots experience damage and stability issues due to peak impact forces during locomotion, which existing solutions like rubber pads or controlled foot deceleration fail to adequately address without compromising speed or balance.
Innovation Solution
A foot assembly with a first portion of lower inertia contacting the terrain first, engaging actuators or compliant elements to reduce the initial vertical velocity of a second portion to zero, ensuring a controlled and smooth transition of forces during each step, thereby minimizing impact forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If rubber pads or thick damping material are added to the feet to reduce impact forces, then impact reduction is improved, but device complexity and energy loss increase
Solution Approach 1:
The foot assembly is divided into multiple portions (first portion with lower inertia and second portion with higher inertia). The first portion makes initial contact with the terrain and engages actuators or compliant elements to reduce impact forces, while the second portion provides stable support. This segmentation allows impact reduction without requiring thick damping material across the entire foot.
Solution Approach 2:
The patent changes the inertia parameter of different foot portions, with the first portion having lower effective inertia than the second portion. This parameter change enables the first portion to respond more quickly to terrain contact and engage the impact reduction mechanism, while the second portion maintains structural stability.
2Object-affected harmful factors
If the foot is controlled to decelerate before landing to reduce impact, then impact forces are reduced, but speed and balance control are compromised
Solution Approach 1:
The first portion of the foot assembly is designed to make preliminary contact with the terrain before the main body of the foot. This preliminary action engages the actuators or compliant elements in advance, allowing gradual deceleration of the second portion without requiring the entire foot to slow down significantly, thus maintaining locomotion speed while reducing impact forces.
3Object-affected harmful factors
If thick damping pads are used to reduce impact, then impact reduction is improved, but energy efficiency deteriorates
Solution Approach 1:
The foot assembly employs dynamic elements including actuators and compliant elements that can actively adjust their behavior during the stepping cycle. These dynamic components engage only during impact reduction phases rather than continuously, improving energy efficiency compared to static thick damping pads that would dissipate energy throughout the entire gait cycle.
4Stability of the object's composition
If rapid foot placement is used to maintain balance, then balance is improved, but impact forces increase
Solution Approach 1:
By segmenting the foot into a first portion for initial contact and a second portion for main support, the system can achieve rapid overall foot placement for balance while the first portion gradually engages the impact reduction mechanism. This allows the foot to be placed quickly without the entire mass impacting simultaneously, reducing peak forces while maintaining balance 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 solution effectively reduces ground impact forces, preventing rigid body collisions and oscillations, allowing for stable and efficient locomotion without energy loss or balance issues.
Implementation Method 1
contact by the first portion with the terrain, when the robot takes a step, causes the one or more of a first actuator and a first compliant element to engage and reduce an initial vertical velocity associated with the second portion to substantially zero
Implementation Method 2
causes the one or more of a first actuator and a first compliant element to engage and reduce an initial vertical velocity associated with the second portion to substantially zero
Data Source
AI summary
A method is disclosed for reducing impact forces to legged robots as a result of traversing a terrain. The method includes employing actuators and compliant elements to use the contact of a first portion of a foot assembly with a terrain during a step to reduce the vertical velocity of a subsequent portion of the foot assembly so that the vertical velocity of the subsequent portion as it touches the terrain is substantially zero relative to the terrain. Foot assemblies that employ these methods are also provided.