A dynamic electrically driven soft valve for control of soft hydraulic actuators

Area of Science:

• Robotics
• Materials Science
• Mechanical Engineering

Background:

• Current regulation systems for fluid-driven soft robots use bulky, inflexible components, limiting mobility.
• Existing soft valves are often fluidically driven, requiring external pressure sources, or electrically driven electrostatic valves with limited pressure modulation.
• State-of-the-art electrostatic valves struggle to exceed 3.5 kPa pressure with adequate flow rates (>6 mL·min⁻¹).

Purpose of the Study:

• To introduce a new electrically powered soft valve for hydraulic actuators in soft robots.
• To overcome the limitations of existing soft valve technologies regarding pressure, flow rate, and power density.
• To demonstrate the potential for advanced onboard motion control in soft fluid-driven robots.

Main Methods:

• Development of a soft valve using ultrahigh-power density dynamic dielectric elastomer actuators (DEAs) for mesoscale hydraulic channels.
• Actuation of DEAs at frequencies of 500 Hz or higher.
• Characterization of valve performance including pressure control, flow rate modulation, response time, and power density.

Main Results:

• The developed DEAs generate 300% higher blocked force and achieve a loaded power density of 290 W·kg⁻¹.
• The compact (7 mm, 0.35 g) DEA soft valves effectively control up to 51 kPa pressure and 40 mL·min⁻¹ flow rate with <0.1 s response time.
• Demonstrated independent control of multiple hydraulic actuators from a single pressure source and tunable flow rates via driving voltage.

Conclusions:

• The novel DEA soft valve offers unprecedented electrical control for hydraulic actuators in soft robots.
• This technology significantly enhances the adaptability and mobility of fluid-driven soft robots.
• The compact and lightweight design shows great potential for future onboard motion control systems in soft robotics.