WPI Soft Robotics Lab, Mechanical Engineering Department, Robotics Engineering Program, Worcester Polytechnic Institute , Worcester, Massachusetts.
Soft Robot. 2017 Jun;4(2):117-125. doi: 10.1089/soro.2016.0041. Epub 2017 Feb 24.
Real-world environments are complex, unstructured, and often fragile. Soft robotics offers a solution for robots to safely interact with the environment and human coworkers, but suffers from a host of challenges in sensing and control of continuously deformable bodies. To overcome these challenges, this article considers a modular soft robotic architecture that offers proprioceptive sensing of pressure-operated bending actuation modules. We present integrated custom magnetic curvature sensors embedded in the neutral axis of bidirectional bending actuators. We describe our recent advances in the design and fabrication of these modules to improve the reliability of proprioceptive curvature feedback over our prior work. In particular, we study the effect of dimensional parameters on improving the linearity of curvature measurements. In addition, we present a sliding-mode controller formulation that drives the binary solenoid valve states directly, giving the control system the ability to hold the actuator steady without continuous pressurization and depressurization. In comparison to other methods, this control approach does not rely on pulse width modulation and hence offers superior dynamic performance (i.e., faster response rates). Our experimental results indicate that the proposed soft robotic modules offer a large range of bending angles with monotonic and more linear embedded curvature measurements, and that the direct sliding-mode control system exhibits improved bandwidth and a notable reduction in binary valve actuation operations compared to our earlier iterative sliding-mode controller.
真实环境复杂、非结构化且往往脆弱。软机器人为机器人与环境和人类同事安全交互提供了一种解决方案，但在连续可变形体的传感和控制方面存在诸多挑战。为了克服这些挑战，本文考虑了一种模块化软机器人架构，该架构提供压力操作弯曲致动器模块的本体感受测。我们提出了嵌入式在双向弯曲致动器中性轴上的集成定制磁曲率传感器。我们描述了我们在这些模块的设计和制造方面的最新进展，以提高我们之前工作中本体感受测曲率反馈的可靠性。特别是，我们研究了尺寸参数对提高曲率测量线性度的影响。此外，我们提出了一种滑模控制器公式，直接驱动二进制电磁阀状态，使控制系统能够在无需连续加压和减压的情况下使致动器保持稳定。与其他方法相比，这种控制方法不依赖于脉冲宽度调制，因此具有更好的动态性能（即更快的响应速度）。我们的实验结果表明，所提出的软机器人模块提供了大范围的弯曲角度，具有单调和更线性的嵌入式曲率测量，并且与我们之前的迭代滑模控制器相比，直接滑模控制系统具有更高的带宽和显著减少的二进制阀致动操作。
