Vertical Articulated Robot Motor Overlap Inertia Reduction
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Solution Overview
Problem
Conventional vertical articulated robots with a motor and speed reducer configuration result in increased inertia around the second rotation axis due to the placement of the seventh arm body's servomotor between the sixth joint's servomotor and arm body, leading to inefficiencies in movement and control.
Innovation Solution
The design positions the first motor to overlap the second motor orthogonally, allowing the tool flange to be closer to the second rotation axis, reducing inertia by eliminating the motor's presence between the tool flange and the second motor, and optionally includes a brake to face the first motor, simplifying the structure and further reducing inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first motor is arranged between the tool flange and the second motor, then the structure is simpler, but the inertia around the second rotation axis increases
Solution Approach 1:
The first motor is positioned to overlap with the second motor in a direction orthogonal to both rotation axes. This spatial arrangement in a different dimension allows the motor components to occupy overlapping projection spaces without interfering with each other's functional positions, thereby reducing the moment of inertia while maintaining structural simplicity
Solution Approach 2:
The first motor is nested within the spatial envelope defined by the second motor's position, with both motors overlapping in the orthogonal direction. This nesting arrangement allows compact positioning that minimizes the distance from the tool flange to the second rotation axis, reducing inertia without requiring a completely separate motor mounting structure
2Weight of moving object
If the tool flange is positioned closer to the second rotation axis, then the inertia decreases, but the space for motor arrangement becomes more constrained
Solution Approach 1:
By utilizing the orthogonal dimension for motor placement, the design accommodates both motors in a compact arrangement that does not increase the footprint in the plane perpendicular to the second rotation axis. This allows the tool flange to be positioned closer to the rotation axis while still providing adequate space for motor mounting and maintenance access
Data Source
AI summary
A vertical articulated robot includes a first joint axis portion including a first motor configured to rotationally drive a tool flange, and a second joint axis portion including a second motor configured to rotationally drive the first joint axis portion. The first motor includes a portion that overlaps the second motor in a direction orthogonal to both a direction in which a first rotation axis extends and a direction in which a second rotation axis extends.