Actuator Leaf Spring Miniaturization via Segmented Support
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Solution Overview
Problem
Miniaturizing series elastic actuators (SEAs) is challenging due to the need to reduce the size of the spring, which results in reduced strength, making it difficult to achieve desired drive control in robots while maintaining compliance and measurement accuracy.
Innovation Solution
An actuator design featuring a leaf spring with one end cantilevered, capable of deflection deformation in the plate thickness direction, and a support member that supports the leaf spring on the deflection side when the transmitted torque exceeds a predetermined value, allowing for miniaturization while maintaining strength and measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the spring in the SEA is miniaturized to reduce the apparatus size, then the volume of the actuator is reduced, but the strength of the spring becomes less than the required strength
Solution Approach 1:
The support member is divided into a first support portion and a second support portion that are separated from each other. The first support portion supports the leaf spring at a first position, while the second support portion supports the leaf spring at a second position. This segmentation allows the leaf spring to be supported at multiple discrete locations, distributing the load and maintaining strength while keeping the overall structure compact.
Solution Approach 2:
The support member extends in the width direction of the leaf spring, providing support not just at a single point but along a dimension. The first and second support portions are positioned at different locations along the width direction, creating a distributed support system that enhances the leaf spring's load-bearing capacity without increasing the vertical height or length of the actuator.
2Volume of moving object
If the spring is miniaturized to reduce actuator size, then the volume decreases, but the measurement accuracy is reduced
Solution Approach 1:
By segmenting the support into multiple support portions, the system can more accurately detect and measure the deflection characteristics of the leaf spring. The distributed support points provide better reference positions for measurement, allowing precise detection of the leaf spring's state even in a miniaturized configuration.
Solution Approach 2:
The patent introduces a detection device that uses optical fields (such as laser sheets) to measure the deflection of the leaf spring. This replaces traditional mechanical measurement methods with optical measurement, enabling high-precision measurement of the leaf spring's deformation state without being constrained by the physical size of the actuator.
3Strength
If the leaf spring is made more rigid to prevent plastic deformation, then the strength increases, but the compliance for drive control is reduced
Solution Approach 1:
The support member is configured to dynamically interact with the leaf spring based on the transmitted torque. When torque exceeds a predetermined value, the leaf spring comes into contact with the support portions, which then provide additional support to prevent plastic deformation. This dynamic support mechanism allows the system to maintain compliance during normal operation while providing rigidity when needed.
Solution Approach 2:
The system changes the effective rigidity parameter of the leaf spring based on operating conditions. During normal operation with low torque, the leaf spring maintains its flexibility for compliance control. When torque exceeds the predetermined threshold, the support portions engage, effectively increasing the rigidity parameter to prevent plastic deformation. This parameter change is achieved through the conditional engagement of the support structure.
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 the miniaturization of the actuator while maintaining high rigidity and measurement accuracy, preventing plastic deformation and ensuring effective drive control in robots.
Implementation Method 1
a leaf spring whose one end is cantilevered, the leaf spring being capable of deflection deformation in a plate thickness direction in accordance with torque by transmitting the torque
Data Source
AI summary
To propose a novel and improved actuator and artificial leg capable of miniaturizing an apparatus.An actuator (320) includes: a leaf spring (322) whose one end (322a) is cantilevered, the leaf spring being capable of deflection deformation in a plate thickness direction in accordance with torque by transmitting the torque; and a support member (324) configured to support a part of the leaf spring on a deflection direction side in a case where the torque transmitted by the leaf spring is greater than a predetermined value.