Nested Two-DOF Motor Structure for Compact Robot Leg Joints
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Solution Overview
Problem
The legged robot's leg-part structure in existing technologies has a large axial volume due to serially connected coaxial motors, occupying a significant arrangement space and lacking compactness.
Innovation Solution
A motor with two degrees of freedom is designed, featuring an outer rotor motor and a disk-type motor coaxially arranged, with separate power output ends for each degree of freedom, and bearing assemblies to ensure smooth rotation and compactness, integrated into a robot's leg-part structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two coaxial motors are used in serial connection to drive thigh and shank, then the leg-part structure can achieve independent control of thigh and shank movements, but the axial volume and arrangement space become relatively large
Solution Approach 1:
The patent applies nesting by placing the disk-type motor inside the outer rotor motor, with the disk-type motor's stator assembly positioned at the center and its rotor disk rotating within the outer rotor motor's magnetic field. This nested configuration allows two independent motor functions to coexist in a compact axial space, resolving the contradiction between independent control capability and compact volume.
Solution Approach 2:
The patent merges two separate motor functions into a single integrated motor assembly where the outer rotor motor and disk-type motor share common structural elements and magnetic circuits. The outer rotor motor's stator assembly and the disk-type motor's stator assembly are combined in a way that allows both motors to operate independently while occupying minimal axial space, thus combining two functions into one compact unit.
2Adaptability or versatility
If two coaxial motors are arranged in serial connection, then each motor can independently drive its respective component, but the overall structure becomes less compact and occupies more space
Solution Approach 1:
The disk-type motor is nested within the outer rotor motor, with the disk-type motor's rotor disk rotating coaxially inside the outer rotor motor's magnetic field. This nesting allows both motors to maintain independent driving capabilities while achieving a compact overall shape that enhances leg-part structure compactness.
Solution Approach 2:
The patent transitions from a conventional side-by-side or serial motor arrangement to a coaxial nested configuration, utilizing the radial dimension to accommodate both motor functions. The disk-type motor's rotor disk rotates in the radial plane within the outer rotor motor's magnetic field, effectively using another spatial dimension to achieve compactness without compromising independent driving capability.
3Volume of moving object
If the motor assembly is made more compact, then the arrangement space is reduced, but the complexity of coordinating two degrees of freedom increases
Solution Approach 1:
The patent merges the control systems of two motors into a unified control architecture where the outer rotor motor and disk-type motor are coordinated through shared control signals. The magnetic circuits and mechanical structures are also merged, allowing the two degrees of freedom to be coordinated more easily despite the compact arrangement, thus reducing control complexity while maintaining small arrangement space.
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 motor achieves compact axial structure and reduced space occupation, enabling simultaneous independent operation of thigh and shank movements, suitable for applications requiring coaxial torque output within limited space, facilitating robot miniaturization.
Implementation Method 1
an outer rotor motor, comprising an outer-rotor-motor stator assembly and an outer rotor disk... a disk-type motor, sleeved in the outer rotor motor and comprising a disk-type-motor stator assembly and an inner rotor disk
Data Source
AI summary
The present application relates to the technical field of motors, and provides a motor with two degrees of freedom and a robot. Such a motor with two degrees of freedom comprises a motor shell, an outer rotor motor and a disk-type motor, wherein the outer rotor motor comprises an outer-rotor-motor stator assembly and an outer rotor disk, the outer-rotor-motor stator assembly is fixed to the motor shell and arranged circumferentially around the motor shell, and the outer rotor disk serves as a power output end of a first degree of freedom; the disk-type motor is sleeved on the outer rotor motor, and comprises an inner rotor disk and a disk-type-motor stator assembly, the disk-type-motor stator assembly is fixed at a central part of the motor shell, and the inner rotor disk serves as a power output end of a second degree of freedom.