A Pneumatic Proportional Valve for Bidirectional Pressure Control for Soft Fluidic Actuators

Soft actuators are increasingly valued for their adaptability to unknown environments and their inherent safety in human–robot interactions. As the scope of soft actuators broadens, there is an increasing demand for actuators capable of handling bidirectional pressure regulation. Existing solutions often face limitations such as high cost, complex control, and large size. Addressing these challenges, this study introduces a compact bidirectional pressure proportional valve (BPPV), measuring only 20 mm × 20 mm × 41 mm. The dual-plunger structure can reduce the cost of BPPV and simplify the control algorithm. The controllable pressure range is −31 kPa to 72 kPa. The maximum temperature increase observed under natural convection conditions was 17.5 $^{\circ }$C. Experimental results demonstrate the BPPV’s ability to precisely regulate bidirectional pressure, making it ideal for tasks such as gripping objects of various sizes and managing soft and fragile items. The BPPV’s compact design, low cost, simple control, stable continuous operation, and suitable pressure range make it particularly well suited for integration into soft robotic systems.