Motorized Joint with Bevel Gear for Compact Humanoid Robot Design
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Solution Overview
Problem
Existing motorized joints with two pivot connections in humanoid robots require two motors, leading to protuberances that impede movements and reduce standardization due to asymmetrical joint design.
Innovation Solution
A joint with non-parallel pivot connections driven by a first motor with a speed reducer and a second motor with a bevel gear, allowing for compact design and reduced protuberance, using a combination of straight and planetary gear trains for efficient movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two motors are aligned with the respective axes of rotation in a joint with two axes at right-angles, then the joint can be implemented in a simple manner, but one of the motors must project in relation to the joint forming a protuberance that impedes certain movements of the robot
Solution Approach 1:
The patent introduces a bevel gear mechanism that changes the spatial dimension of power transmission. Instead of aligning motors directly with rotation axes in the same dimension, the bevel gear transmits power at an angle (typically 90 degrees), allowing the motor to be positioned in a different spatial dimension relative to the joint axis, thereby eliminating the protuberance that would impede movement.
2Adaptability or versatility
If the motors at the elbows are placed symmetrically relative to the vertebral column to allow the robot to place its arms along its body, then the robot can achieve proper arm positioning, but the joints cannot be identical which reduces the standardization of the mechanical parts
Solution Approach 1:
The patent employs asymmetric motor positioning combined with bevel gear mechanisms. The bevel gear allows the motor to be positioned asymmetrically relative to the joint axis while still achieving the required rotational output. This asymmetric configuration enables both left and right elbow joints to use identical standardized components, yet be positioned symmetrically on the robot's body for proper arm placement.
3Volume of moving object
If a bevel gear is introduced between the motor and the pivot connection in one of the reducers, then the compactness of the joint is improved and motor protuberances are eliminated, but the device complexity increases due to the additional gear mechanism
Solution Approach 1:
The patent merges the bevel gear mechanism with the existing speed reducer assembly. Instead of adding a completely separate power transmission system, the bevel gear is integrated into one of the two speed reducers that already exist in the joint. This merging approach achieves compactness and eliminates motor protuberances while minimizing the increase in overall device complexity by reusing existing structural elements.
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 enables improved compactness and standardization of joints, reducing mechanical complexity and enhancing movement flexibility by eliminating motor protuberances and allowing for symmetrical joint design.
Implementation Method 1
one of the two reducers comprises a bevel gear between the motor and the pivot connection which are associated by this reducer
Data Source
AI summary
A motorized joint having two degrees of freedom in rotation connecting two elements is provided. The joint includes two pivot connections such that a first one of the pivot connections establishes a first pivot axis, and a second one of the pivot connections establishes a second pivot axis. The first pivot axis is not parallel to the second pivot axis. A first motor is disposed in fixed relation to a first one of the two elements and has a drive shaft aligned with a first drive axis so as to cause by means of a first speed reducer with parallel axes the two elements to rotate about the first pivot axis. A second motor having a second drive shaft aliened with a second drive axis parallel to the first drive axis of the first motor is affixed to an output portion of the first speed reducer for axial rotation therewith about the first pivot axis so as to cause by means of a second speed reducer including a bevel gear relative rotational movement of the two elements with respect to one another about the second pivot axis. Also, the joint may be implemented as part of a humanoid robot.