Rotational Driving Mechanism with Linkage for Robot Joint Actuator
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Solution Overview
Problem
Conventional joint parts in humanoid robots require large actuators due to the arrangement of output shafts and linkage mechanisms, which increases size and load torque, and lacks effective mechanisms to alleviate gravity loads during rotary motion.
Innovation Solution
A rotational driving mechanism using a linear motion actuator with a seesaw-like link mechanism to transmit force efficiently, reducing the size of the actuator and alleviating gravity loads by adjusting link unit positions based on the rotary member's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotary actuator is mounted on the joint part to drive the rotary member, then the rotary member can be driven to rotate, but the actuator size increases and load torque increases when the rotation angle increases
Solution Approach 1:
The patent replaces the rotary actuator with a linear motion actuator that drives a linkage mechanism. The linear actuator pulls a link that rocks like a seesaw, converting linear motion into rotational motion of the rotary member. This substitution allows the actuator to be mounted on the base member rather than the joint part, reducing the actuator size and changing the mounting location.
Solution Approach 2:
The patent introduces a linkage mechanism as an intermediary between the linear motion actuator and the rotary member. The linkage mechanism includes a link that rocks like a seesaw and another link that connects to the rotary member, converting the linear motion from the actuator into rotational motion. This intermediary mechanism allows the actuator to be smaller and mounted differently while still achieving the desired rotational driving.
2Ease of manufacture
If the output shaft of the actuator and the arm of the linkage mechanism are arranged in series, then the driving force can be transmitted, but the lengthwise dimension increases and arrangement location is restricted
Solution Approach 1:
The patent changes the arrangement from a linear series configuration to a configuration that utilizes rotational movement and different spatial dimensions. The link rocks like a seesaw, moving in an arc rather than in a straight line, and the second link connects at an angle to the rotary member. This dimensional change allows the mechanism to fit in a more compact space with fewer restrictions on arrangement location.
3Ease of manufacture
If conventional linkage mechanisms are used to transmit driving force, then the driving force can be transmitted to the base member, but the gravity load on the actuator is not alleviated
Solution Approach 1:
The patent uses the linkage mechanism to counteract the gravity load on the actuator. As the rotary member moves, the linkage mechanism is designed to provide mechanical advantage that reduces the net force the actuator must exert against gravity. The rocking motion of the first link and the angled connection of the second link create a mechanical system that can alleviate the gravity load during certain phases of the rotational 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
The mechanism achieves a reduction in actuator size and load, allowing for compact and efficient rotational driving of rotary members while managing gravity loads effectively.
Implementation Method 1
the first link unit will operate as a rocking link rocking like a seesaw by the support of the first support part
Implementation Method 2
a linear motion actuator is adopted for rotational driving of a rotary member
Data Source
AI summary
A rotational driving mechanism for driving a rotary member mounted on a rotatable base member includes: a first link unit that has a first link body and is mounted through a first support part on the base member, the first link unit further having an input part to which an output of the linear motion actuator is inputted at one side of the first link body, and an output part located in the first link body at an opposite side of the input part across the first support part; and a second link unit that has a second link body and is mounted through a second support part on the output part of the first link unit, the second link unit being further mounted through a third support unit on the rotary member or a connecting member joined thereto in such a manner as to be free to rotate.