Pneumatically actuated soft robots have recently shown promise for their ability to adapt to their environment. Previously, these robots have been controlled with electromechanical components, such as valves and pumps, that are typically bulky and expensive. Here, we present an approach for controlling the gaits of soft-legged robots using simple pneumatic circuits without any electronic components. This approach produces locomotive gaits using ring oscillators composed of soft valves that generate oscillating signals analogous to biological central pattern generator neural circuits, which are acted upon by pneumatic logic components in response to sensor inputs. Our robot requires only a constant source of pressurized air to power both control and actuation systems. We demonstrate this approach by designing pneumatic control circuits to generate walking gaits for a soft-legged quadruped with three degrees of freedom per leg and to switch between gaits to control the direction of locomotion. In experiments, we controlled a basic walking gait using only three pneumatic memory elements (valves). With two oscillator circuits (seven valves), we were able to improve locomotion speed by 270%. Furthermore, with a pneumatic memory element we designed to mimic a double-pole double-throw switch, we demonstrated a control circuit that allowed the robot to select between gaits for omnidirectional locomotion and to respond to sensor input. This work represents a step toward fully autonomous, electronics-free walking robots for applications including low-cost robotics for entertainment and systems for operation in environments where electronics may not be suitable.

气动驱动的软机器人最近显示出适应环境的能力。以前，这些机器人是由机电组件控制的，例如阀门和泵，这些组件通常体积庞大且价格昂贵。在这里，我们提出了一种使用没有任何电子元件的简单气动电路来控制软腿机器人步态的方法。这种方法使用由软阀组成的环形振荡器产生机车步态，该振荡器产生类似于生物中央模式发生器神经电路的振荡信号，气动逻辑组件响应传感器输入对这些信号起作用。我们的机器人只需要一个恒定的压缩空气源来为控制和驱动系统提供动力。我们通过设计气动控制电路来为每条腿具有三个自由度的软腿四足动物生成步行步态并在步态之间切换以控制运动方向来演示这种方法。在实验中，我们仅使用三个气动记忆元件（阀门）来控制基本的步行步态。使用两个振荡器电路（七个阀门），我们能够将移动速度提高 270%。此外，我们设计了一个气动记忆元件来模拟双刀双掷开关，我们展示了一个控制电路，该电路允许机器人在全向运动的步态之间进行选择，并对传感器输入做出响应。这项工作代表着迈向完全自主的一步，