Electromagnetic Spherical Wrist for Decoupled Motion
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Solution Overview
Problem
Current robotic wrists for space and extreme environments face challenges with complex mechanical structures, low control accuracy, and difficulty in achieving active compliance control due to nonlinear friction, leading to poor dynamic performance and mechanical efficiency.
Innovation Solution
An electromagnetic drive spherical robotic wrist with two degrees of freedom is developed, utilizing a coaxial following magnetic torque of a spatial universal rotational magnetic field to achieve pitch and yaw rotation, combined with a built-in permanent magnet cylinder and universal joints, enabling variable stiffness and compliance control through electromagnetic feed-forward compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gear drive transmission is adopted in robotic wrist, then the wrist can achieve multi-degree of freedom motion, but the structure becomes complex and the integration level is low
Solution Approach 1:
The patent replaces the traditional gear drive mechanical transmission system with an electromagnetic drive system. The electromagnetic drive directly generates rotational motion without mechanical gears, eliminating the complex gear train while achieving the same multi-degree of freedom motion capability. This substitution resolves the contradiction by maintaining adaptability while reducing structural complexity.
Solution Approach 2:
The patent extracts and removes the gear transmission components from the wrist mechanism. By taking out the gear drive system and replacing it with direct electromagnetic drive, the complex mechanical structure is eliminated while the essential function of multi-degree of freedom motion is preserved through the electromagnetic actuation system.
2Productivity
If mechanical transmission structure is used in robotic wrist, then motion transmission can be achieved, but nonlinear friction occurs leading to poor control accuracy
Solution Approach 1:
The patent eliminates mechanical transmission components that generate nonlinear friction by substituting them with an electromagnetic drive system. The electromagnetic drive directly actuates the wrist joints without intermediate mechanical contacts, thereby removing the friction source while maintaining motion transmission capability. This resolves the contradiction by preserving productivity while improving control accuracy.
3Ease of operation
If spherical wrist mechanism with three intersecting joint axes is adopted, then position and posture can be decoupled, but the structure is complex and weight is difficult to reduce
Solution Approach 1:
The patent replaces the complex spherical wrist mechanism with three intersecting joint axes with a simplified electromagnetic drive system. The electromagnetic actuators directly generate the required rotational motions while maintaining the decoupling of position and posture control through independent actuation of each degree of freedom. This substitution reduces structural complexity while preserving operational ease.
4Adaptability or versatility
If non-spherical wrist with three non-intersecting axes is adopted, then rotation angle can exceed 360°, but the structure is not compact and volume is large
Solution Approach 1:
The patent replaces the non-spherical wrist mechanism with compact electromagnetic drive system. The electromagnetic actuators generate the required large rotation angles exceeding 360° through direct electromagnetic torque without requiring the large mechanical structure of non-spherical wrist. This substitution maintains adaptability while significantly reducing the wrist volume.
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 solution simplifies the mechanical structure, eliminates nonlinear friction, and enhances motion performance, control response speed, and location accuracy, allowing for precise and efficient operation in complex environments.
Implementation Method 1
utilizing a coaxial following magnetic torque of a spatial universal rotational magnetic field to achieve pitch and yaw rotation
Implementation Method 2
a three-axis Helmholtz coil assembly provides a spatial universal rotational magnetic field
Implementation Method 3
electromagnetic drive spherical robotic wrist with two degrees of freedom, utilizes a coaxial following magnetic torque
Data Source
AI summary
An electromagnetic drive spherical robotic wrist with two degrees of freedom and a control method therefor, which is particularly a highly integrated active spherical robotic wrist, realizes pitch and yaw rotation with two degrees of freedom under the direct drive of a coaxial following magnetic torque of a spatial universal rotational magnetic field through a built-in permanent magnet cylinder with radial magnetization of a following mechanism formed by coaxial connection of two output ends of internal and external universal joints with the same rotation center. The electromagnetic drive spherical robotic wrist overcomes the disadvantages of a complex transmission mechanical wrist, and a wrist transmission system has a simple and light structure, high transmission efficiency, good static and dynamic performance, and fast control response.