Origami-Inspired Structure with Pneumatic-Induced Variable Stiffness for Multi-DOF Force-Sensing.

Area of Science:

• Robotics and Human-Machine Systems
• Materials Science and Engineering
• Sensor Technology

Background:

• Growing demand for multi-modal human-machine interaction necessitates advanced sensory devices.
• Current force sensors lack adjustable sensitivity post-fabrication, limiting adaptability.
• Flexible, adaptive, and stiffness-variable force sensors are crucial for human-machine fusion.

Purpose of the Study:

• To develop a novel origami-inspired structure for flexible force-sensing with variable stiffness.
• To achieve multiple degrees of freedom (DoFs) motions for enhanced force adaptability.
• To integrate an ultra-flexible microfiber sensor for closed-loop control and diverse sensing capabilities.

Main Methods:

• Utilized an origami-inspired structure combined with pneumatic actuation for five motion modes (compression, pitch, roll, diagonal, array).
• Embedded an ultra-flexible microfiber sensor with distinct linear and exponential sensitivity ranges (0-100 kPa and 100-350 kPa).
• Investigated the effect of pre-pressure on sensor sensitivity through calibration experiments.

Main Results:

• The origami structure enabled variable stiffness and multiple motion modes, increasing force adaptability.
• The embedded microfiber sensor demonstrated approximately linear sensitivity (∼0.35 Ω/kPa) up to 100 kPa and exponential sensitivity thereafter.
• Increasing pre-pressure (65-95 kPa) shifted sensitivity curves, enhancing force-sensing capability in the 0-2 N range, reaching 11.6 Ω/N at 100 kPa pre-pressure.

Conclusions:

• The proposed origami-inspired, stiffness-variable force sensor offers a low-cost, highly integrated solution for flexible force sensing.
• The design significantly enhances force adaptability and sensing diversity through multi-DoF motion and adjustable sensitivity.
• This technology holds great potential for advancing human-machine interaction and flexible robotics.