Buckling Actuator Stiffness Control for Force and Position Tracking
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Solution Overview
Problem
Existing actuator technologies lack the ability to control and vary negative stiffness, which is essential for precise motion control and force tracking in applications such as robotics and human-machine interaction.
Innovation Solution
The method involves applying a load to a member to cause buckling, resulting in non-linear deflection characteristics that define the effective stiffness of the actuator, allowing for the variation of stiffness to include positive, zero, and negative values, and controlling the position of an end effector based on the estimated force and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional actuators are used, then basic motion conversion is achieved, but the ability to control and vary negative stiffness is lacking
Solution Approach 1:
The patent implements dynamic stiffness control by applying variable loads to the buckling beam, allowing the actuator to transition between different stiffness states (positive, zero, and negative) during operation. The load is adjusted in real-time to achieve desired stiffness characteristics for different application requirements.
Solution Approach 2:
The patent changes the physical parameter of the beam by applying compressive loads that induce buckling, transforming the beam from a straight configuration to a buckled configuration. This parameter change enables the generation of negative stiffness while maintaining a relatively simple actuator structure.
2Length of moving object
If buckling beams are used to amplify displacement, then displacement range is increased, but control of negative stiffness is not achieved
Solution Approach 1:
The patent replaces traditional mechanical stiffness control mechanisms with a load-controlled buckling beam system. By applying controlled loads to induce buckling, the system achieves negative stiffness without requiring complex mechanical adjustment mechanisms, thereby maintaining simple structure while enabling precise stiffness control.
3Measurement precision
If thermal actuators are used for multi-position actuation, then positioning capability is improved, but force control resolution is insufficient
Solution Approach 1:
The patent implements feedback control by continuously monitoring the force applied to the end effector and adjusting the load on the buckling beam accordingly. This feedback mechanism enables high-resolution force control and position tracking by dynamically adjusting the stiffness to match the desired force-displacement relationship.
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 approach enables better force control and position tracking with higher resolution, making actuators actively backdriveable and suitable for various applications by varying the effective stiffness of the actuator.
Implementation Method 1
the load causes the member to buckle and the buckling of the member defines at least in part the non-linear deflection characteristics of buckling
Implementation Method 2
applying a load to a member... controlling a position of an end effector of the actuator based at least in part on a force applied to the end effector
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An actuator [100, 400, 500, 550, 600, 650, 700, 800, 900, 910, 925] includes an effective stiffness. The effective stiffness is based at least in part on non-linear deflection characteristics of buckling. A method of varying an effective stiffness of an actuator includes providing an actuator and varying an effective stiffness of the actuator based at least in part on non-linear deflection characteristics of buckling.