Robot Joint Motor Bolt Positioning for Arm Rigidity
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Solution Overview
Problem
The existing joint structures in robots face issues with arm rigidity due to recess formation for bolt insertion, leading to reduced rigidity and a degraded appearance from visible bolts, especially when a high number of bolts are required to secure the arm to the reduction gear.
Innovation Solution
A joint structure is introduced where a servo motor is fixed to an interposition member with motor fixing bolts, and the reduction gear case is fixed to the arm with support member fixing bolts, arranged in a way that the motor fixing bolts are positioned away from the support member fixing bolts, allowing for improved arm shape flexibility and reduced visibility of bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the arm is formed to be thin with recesses for bolt insertion, then the appearance is improved and bolts can be hidden, but the rigidity of the arm is reduced
Solution Approach 1:
The patent moves the bolt insertion holes from the outer surface (2D plane) to the inner surface of the arm, utilizing the third dimension (depth/thickness) to resolve the conflict between appearance and structural integrity. This allows the arm to maintain its outer shape without recesses while still providing access for bolt insertion from the inside.
2Reliability
If a large number of bolts are used to fix the arm to the reduction gear, then the reliability of the connection is improved, but the appearance is degraded due to visible bolts
Solution Approach 1:
The patent utilizes the inner surface dimension of the arm to position multiple bolt holes, allowing numerous bolts to be arranged in a compact circular pattern on the inner surface. This enables reliable connection of multiple bolts while keeping them hidden from the external view, maintaining aesthetic appearance.
3Device complexity
If the motor fixing bolts and support member fixing bolts are arranged close together, then the device complexity is reduced, but the manufacturing precision is worsened due to interference
Solution Approach 1:
The patent resolves the interference between motor fixing bolts and support member fixing bolts by utilizing the inner surface dimension. Both sets of bolts can be arranged in close proximity on the inner surface without interfering with each other, maintaining simple overall structure while achieving precise positioning for both mounting operations.
Data Source
AI summary
A structure of a joint includes a reduction gear including a shaft configured to support a gear and including a reduction gear case to which rotational force of the gear is transmitted. The joint includes an interposition member interposed between a servo motor and a pivot base. The servo motor is fixed to the interposition member with motor fixing bolts. The shaft is fixed to the pivot base with shaft fixing bolts. A diameter of the positions of the motor fixing bolts and a diameter of the positions of the shaft fixing bolts are smaller than an outer diameter of the reduction gear case. The interposition member has a shape for fixing the motor fixing bolts at positions away from the shaft fixing bolts.