Spherical Force Transmission for Backlash-Free Robot Hands
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Solution Overview
Problem
Driving force transmission devices with nonparallel rotation axes suffer from significant backlash, which is detrimental for precise operations in robotic applications.
Innovation Solution
A driving force transmission device comprising a first rotator with a concave surface and a second rotator with a convex surface, along with a plurality of spheres positioned between them, where the concave surface has holes and the convex surface has grooves that maintain a pressurized state with a pressure angle of 60° or less, minimizing backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bevel gears are used to transmit driving force between nonparallel rotation axes, then the transmission function is achieved, but significant gear backlash occurs
Solution Approach 1:
The invention replaces traditional bevel gears with spherical transmission elements. The first rotator has a spherical outer surface, the second rotator has a spherical inner surface, and multiple spheres are arranged between them. This spherical geometry allows for continuous contact and force transmission between nonparallel rotation axes while eliminating the discrete tooth engagement that causes backlash in conventional gears.
Solution Approach 2:
Multiple spheres act as intermediary elements between the first rotator and second rotator. These spheres are positioned in the space between the two rotators and transmit the driving force through their contact with both surfaces. The spheres serve as mediators that enable force transmission while maintaining the ability to accommodate nonparallel rotation axes without creating backlash.
2Manufacturing precision
If spheres are positioned between concave and convex surfaces for force transmission, then backlash is avoided, but the structure becomes more complex
Solution Approach 1:
The invention integrates multiple functional elements into unified structures. The concave surface with recesses and the convex surface with protrusions are designed as complementary integrated features rather than separate components. The spheres are positioned to engage with both surfaces simultaneously, merging the transmission function into a compact arrangement that reduces overall structural complexity despite the presence of multiple spheres.
Solution Approach 2:
The concave surface is provided with recesses at specific locations, and the convex surface has protrusions corresponding to these recesses. This localized feature distribution allows the spheres to be precisely positioned and engaged only where needed for force transmission. The local quality variations in the surfaces enable accurate sphere positioning while maintaining a relatively simple overall structure.
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 effectively reduces backlash, ensuring stable and precise transmission of driving forces across the rotation range, enhancing the accuracy and reliability of robotic operations.
Implementation Method 1
the plurality of spheres received in the plurality of holes revolve about a rotation axis of the first rotator and move along the groove between the concave surface and the convex surface being out of contact with each other
Implementation Method 2
The pressurized state is a state in which at least one of the plurality of spheres has a pressure angle of 60° or less. The pressure angle is, at each position in the at least one bend, an angle between a direction normal to an outer opening edge of an opening edge of the at least one bend and the moving direction of each of the plurality of spheres.
Data Source
AI summary
A driving force transmission device includes an input section and an output section with rotation axes nonparallel to each other to avoid backlash. A driving force transmission device (1) includes a first rotator (2), a second rotator (3), and spheres (5A, 5B, 5C). The first rotator (2) performs one of an input operation and an output operation of a driving force and includes a concave surface (7). The second rotator (3) performs the other of the input operation and the output operation of the driving force and includes a convex surface (13) fitted into the concave surface (7). The spheres (5A, 5B, 5C) are between the concave surface (7) and the convex surface (13). The concave surface (7) has holes (32A, 32B, 32C) in which the respective spheres (5A, 5B, 5C) are received. The convex (13) surface has a groove (29, 30) that receives parts of the spheres (5A, 5B, 5C) protruding from the holes (32A, 32B, 32C).