Two-DOF Link Drive Mechanism for Wide Angle Motion
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Solution Overview
Problem
Conventional drive mechanisms for robots with joint structures face challenges in achieving a large operation angle range of two degrees of freedom while minimizing structural deflection, particularly requiring large gears that compromise compactness.
Innovation Solution
A drive mechanism featuring a spherical joint connection between the first and second link members, paired cylinders rotating about a perpendicular axis, and a power transmission unit with link mechanisms that allow for independent operation of roll and pitch movements without a planetary gear speed increasing mechanism, enabling a compact configuration with reduced deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planetary gear speed increasing mechanism is applied to achieve large operation angle range, then the operation angle range is improved, but the device complexity and size increase
Solution Approach 1:
The invention extracts and eliminates the planetary gear speed increasing mechanism from the drive system. By directly connecting the drive source to the link mechanism without intermediate speed increasing gears, the patent achieves a simplified structure that avoids the complexity and size issues of conventional planetary gear systems while maintaining the ability to achieve large operation angles through the link mechanism's geometric configuration
Solution Approach 2:
The drive mechanism is segmented into distinct functional modules: drive sources (electric cylinders), link mechanisms (first and second link members), and spherical joints. This segmentation allows each component to be optimized independently and facilitates compact arrangement, eliminating the need for a single complex planetary gear system while achieving the desired two-degree-of-freedom motion
2Force
If large gears are used to ensure required joint torque, then the torque capability is improved, but the device size increases and compactness is reduced
Solution Approach 1:
The invention replaces the conventional mechanical gear transmission system with a direct-drive link mechanism. Electric cylinders provide torque directly to the link members, eliminating the need for large gears. The link mechanism's lever arms and spherical joints transmit this torque efficiently to achieve the required joint torque with significantly reduced component size
Solution Approach 2:
The link mechanism utilizes dynamic geometric relationships between the first and second link members connected by spherical joints. This dynamic configuration allows the mechanism to achieve mechanical advantage through its geometry rather than through fixed gear ratios, enabling compact design while maintaining torque capability across the full range of motion
3Adaptability or versatility
If the operation angle range is increased, then the adaptability is improved, but the structural deflection increases
Solution Approach 1:
The invention employs spherical joints at critical connection points (between link members and at the driven body) to accommodate large operation angles. The spherical geometry allows for multi-axis rotation and maintains consistent contact surfaces throughout the range of motion, reducing stress concentrations and minimizing structural deflection even when operating at extreme angles
Solution Approach 2:
The link mechanism uses asymmetric link lengths and arrangements (first link member with length L1, second link member with length L2) optimized for the specific application requirements. This asymmetric configuration allows the mechanism to achieve large operation angles while maintaining structural rigidity and minimizing deflection by positioning support elements strategically
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
This configuration ensures a desired operation angle range of two degrees of freedom in a driven body with reduced structural deflection and enhanced compactness, improving mechanical efficiency and arrangement flexibility, and allowing for shorter electric cylinder strokes.
Implementation Method 1
the distal end portion of the first link member and the base end portion of the second link member are connected by a spherical joint
Implementation Method 2
a first drive source (electric cylinder) and a second drive source (electric cylinder) are provided as viewable from the first imaginary plane
Data Source
Figure 1
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AI summary
A power transmission unit of a drive mechanism (1) has a link mechanism (10) on both sides of a base portion (3). The link mechanism (10) has a first link member (11) having a base end portion provided to the base portion (3) so as to be rotated about a third rotational axis (A3), a second link member (12) having a base end portion connected to a distal end portion of the first link member (11) so as to be rotated about a fourth rotational axis (A4), and a third link member (13) which is provided to a driven body (2) so as to be rotated about a fifth rotational axis (A5) and to which a distal end portion of the second link member (12) is provided so as to be rotated about a sixth rotational axis (A6) orthogonal to the fifth rotational axis (A5). A desired operation angle range of two degrees of freedom in a driven body can be ensured with a compact configuration while suppressing deflection of a structure to which the driven body is mounted.