Electromagnetic Clutch Soft Actuator for Wide Stiffness Control
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Solution Overview
Problem
Existing variable stiffness actuators face limitations such as a limited range of stiffness adjustment, complex control algorithms, coupling interference, high friction in the stiffness adjustment mechanism, small joint rotation angles, and slow response speeds, which hinder their application in human-robot interaction.
Innovation Solution
A soft actuator design featuring a power input shaft with coaxially connected electromagnetic clutches, bending elastic parts, and a simple control method that adjusts output stiffness by controlling the number of elastic elements and using a coaxial friction disc to reduce mechanical disturbance, allowing for a wide range of stiffness adjustments from infinitesimal to infinity with fast response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing variable stiffness actuators use complex mechanisms to adjust stiffness, then stiffness adjustment capability is achieved, but mechanical disturbance and friction increase
Solution Approach 1:
The patent replaces complex mechanical stiffness adjustment mechanisms with electromagnetic clutches that can engage or disengage elastic elements. This substitution eliminates the need for friction-based mechanical adjustment, reducing mechanical disturbance and friction while maintaining stiffness adjustment capability through electromagnetic control.
Solution Approach 2:
The patent extracts the stiffness adjustment function from complex mechanical mechanisms and implements it through selective engagement of elastic elements via electromagnetic clutches. This separation allows the actuator to achieve variable stiffness without the harmful effects of complex mechanical adjustment mechanisms.
2Measurement precision
If traditional robots use high rigidity for high accuracy, then control accuracy is improved, but safety and softness in human-robot interaction deteriorate
Solution Approach 1:
The patent implements dynamic stiffness adjustment by selectively engaging electromagnetic clutches to connect or disconnect elastic elements in real-time. This allows the actuator to transition between high stiffness (for accuracy) and low stiffness (for safety) states, resolving the contradiction between control accuracy and safety in human-robot interaction.
Solution Approach 2:
The patent changes the stiffness parameter dynamically by controlling the engagement state of electromagnetic clutches. When clutches are engaged, elastic elements provide compliance for safety; when disengaged, the system achieves high rigidity for accurate control, thus adapting the stiffness parameter to different operational requirements.
3Adaptability or versatility
If variable stiffness mechanisms use multiple elastic elements with different stiffness, then stiffness adjustment range increases, but device complexity increases
Solution Approach 1:
The patent segments the stiffness adjustment function into multiple independent electromagnetic clutches, each controlling a specific elastic element. This segmentation allows for a wide stiffness adjustment range by selectively combining different elastic elements while keeping each control unit simple and modular, thus managing overall system complexity.
Solution Approach 2:
The patent designs electromagnetic clutches that can universally control different elastic elements with varying stiffness characteristics. This multi-functionality allows a single clutch design to manage multiple elastic elements, reducing the need for specialized components for each stiffness level and thereby simplifying the overall device 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 provides a soft actuator with a simple control algorithm, large variable stiffness range, wide joint rotation angles, fast stiffness adjustment speed, and minimal mechanical disturbance, enhancing system stability and safety in human-robot interaction by avoiding vibrations and ensuring consistent stiffness in both directions.
Implementation Method 1
When the electromagnetic clutch is energized, the electromagnetic attraction force connects the active friction disc and passive friction disc
Implementation Method 2
a bending elastic part is arranged between the thrust plate of each electromagnetic clutch and the electromagnetic clutch gear frame
Data Source
AI summary
A soft actuator includes a power input shaft, and multiple electromagnetic clutches are coaxially installed in series on the power input shaft. A bending elastic part is arranged between the thrust plate of each electromagnetic clutch and the gear frame of the electromagnetic clutch.The bending elastic part is installed on the sleeve of the gear frame and in contact with the baffle of the gear frame. The bending elastic part is connected with the clutch output gear of the electromagnetic clutch through the gear frame. The gear frame is fixedly connected with the clutch output gear and rotates coaxially.