A Programmable Pneumatic System With Novel Improved Controller Enabling Adhesion and Desorption Operations of Soft Adhesive Robots

The inherent flexibility and nonlinearity of soft robots bring a challenge to their actuation and controlling. Especially, developing a portable drive and control system for bionic adhesive pneumatic soft robots (BAPSRs), with high accuracy and responsiveness to improve adhesion and desorption operations, remains a difficult task. In this paper, we aim to develop a high-integration programmable pneumatic system (hiPPS) for use in untethered, size-limited, weight-constrained soft robot applications. The complete design and operational mode are demonstrated, specifically, the dynamic electro-pneumatic characteristics of the system are illustrated through the construction of a microcontroller-based pressure control system that achieves high-integration and programmability. Based on the characteristic curve, an improved fuzzy piecewise PID feedback controller is proposed for the hiPPS system to achieve precise and continuous pressure supply and regulation, as well as to adjust the speed of inflation and deflation. Experimental results indicate that the hiPPS with the novel improved controller can achieve a wide range of pressure from -60 to 100 kPa, with pressure errors within 1.5 kPa, and outperformed a regular controller in realizing adhesion and desorption operations for BAPSRs. Our system liberates the pneumatic soft robots (PSRs) from tethered cumbersome air supply and trivial components by making a lightweight, small-scale pneumatic system with fine-grained control, which enables new possibilities for mobile soft robots. Note to Practitioners—The motivations of this article encompass two aspects: firstly, to provide a versatile, small-volume, lightweight, low-cost, and highly integrated pneumatic solution for PSRs that can generate hybrid pressure supplies, rivaling pneumatic systems composed of bulky pressure supplies and costly proportional valves; secondly, to address the issue of oscillation and fluctuation often encountered when adjusting the duty cycle of switching times in existing pneumatic systems composed of air pumps and low-cost on/off valves. In response to these challenges, we have developed the 93 g hiPPS system and proposed an improved control strategy that proactively adapts to the inherent characteristics of the system. This strategy employs special fuzzy piecewise processing of the reference pressure based on the actual tested electro-pneumatic characteristic curves of the system, thereby achieving continuous and precise pressure regulation, as well as controllable inflation and deflation speeds. The hiPPS system can be easily and rapidly applied to drive and control other single- or multi-chamber PSRs. In future research, we will extend the proposed system and strategy to hydraulic systems and the requirements of mobile PSRs.