Soft Robotics

Soft Robotics (2020): Miniaturized Circuitry for Capacitive Self-sensing and Closed-loop Control of Soft Electrostatic Transducers

Anonymous — Sat, 23 Jan 2021 22:04:41 +0000

Soft Robotics (2020): Miniaturized Circuitry for Capacitive Self-sensing and Closed-loop Control of Soft Electrostatic Transducers Anonymous (not verified) Sat, 01/23/2021 - 15:04

[video:https://youtu.be/fw3BwmrpdmU]

Abstract: Soft robotics is a field of robotic system design characterized by materials and structures that exhibit large-scale deformation, high compliance, and rich multifunctionality. The incorporation of soft and deformable structures endows soft robotic systems with the compliance and resiliency that makes them well adapted for unstructured and dynamic environments. Although actuation mechanisms for soft robots vary widely, soft electrostatic transducers such as dielectric elastomer actuators (DEAs) and hydraulically amplified self-healing electrostatic (HASEL) actuators have demonstrated promise due to their muscle-like performance and capacitive self-sensing capabilities. Despite previous efforts to implement self-sensing in electrostatic transducers by overlaying sinusoidal low-voltage signals, these designs still require sensing high-voltage signals, requiring bulky components that prevent integration with miniature untethered soft robots. We present a circuit design that eliminates the need for any high-voltage sensing components, thereby facilitating the design of simple low cost circuits using off-the-shelf components. Using this circuit, we perform simultaneous sensing and actuation for a range of electrostatic transducers including circular DEAs and HASEL actuators and demonstrate accurate estimated displacements with errors <4%. We further develop this circuit into a compact and portable system that couples high voltage actuation, sensing, and computation as a prototype toward untethered multifunctional soft robotic systems. Finally, we demonstrate the capabilities of our self-sensing design through feedback control of a robotic arm powered by Peano-HASEL actuators..

Ly, K., Kellaris, N., McMorris, D., Johnson, B.K., Acome, E., Sundaram, V., Naris, M., Humbert, J.S., Rentschler, M.E., Keplinger, C., Correll, N., “Miniaturized Circuitry for Capacitive Self-sensing and Closed-loop Control of Soft Electrostatic Transducers,” Soft Robotics.

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IEEE International Conference on Soft Robotics (RoboSoft) (2020): Identification and Control of a Nonlinear Soft Actuator and Sensor System

Anonymous — Sun, 23 Aug 2020 19:55:16 +0000

IEEE International Conference on Soft Robotics (RoboSoft) (2020): Identification and Control of a Nonlinear Soft Actuator and Sensor System Anonymous (not verified) Sun, 08/23/2020 - 13:55

[video: https://youtu.be/EcBuuulZMjY]

Abstract: Soft robots are becoming increasingly prevalent, with unique applications to medical devices and wearable technology. Understanding the dynamics of nonlinear soft actuators is crucial to creating controllable soft robots. this letter presents a system identification process and closed-loop control of foldable HASEL (hydraulically amplified self-healing electrostatic) soft actuators. We characterized foldable HASELs with linear frequency response tests and modeled them using a linear superposition of static and dynamic terms. We also identified two responses of the system: an activation and relaxation response. Based on these two responses, we developed a dual-mode controller which was validated through closed-loop control using a capacitive elastomeric strain sensor wrapped around the actuator. Using this integrated sensor, we achieved step response rise times as fast as 0.025 s and settling times as fast as 0.17 s while under load. These system identification and control techniques can be applied to any HASEL-driven soft robot and could be applied to other soft actuators to enable controllable soft robots.

Johnson, B.K., Sundaram, V., Naris, M., Acome, E., Ly, K., Correll, N., Keplinger, C.M., Humbert, J.S., Rentschler, M.E., “Identification and Control of a Nonlinear Soft Actuator and Sensor System,” IEEE International Conference on Soft Robotics (RoboSoft), Yale University, April, 2020.

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IEEE Robotics and Automation Letters (2020): Identification and Control of a Nonlinear Soft Actuator and Sensor System

Anonymous — Sun, 23 Aug 2020 19:40:03 +0000

IEEE Robotics and Automation Letters (2020): Identification and Control of a Nonlinear Soft Actuator and Sensor System Anonymous (not verified) Sun, 08/23/2020 - 13:40

[video:https://youtu.be/gXO46FtMJp4]

Johnson, B.K., Sundaram, V., Naris, M., Acome, E., Ly, K., Correll, N., Keplinger, C.M., Humbert, J.S., Rentschler, M.E., “Identification and Control of a Nonlinear Soft Actuator and Sensor System,” IEEE Robotics and Automation Letters. 5(3): 3783-3790, 2020.

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IEEE International Conference on Robotics and Automation (2017): Design, Modeling and Control of a SMA-Actuated Biomimetic Robot with Novel Functional Skin

Anonymous — Fri, 21 Apr 2017 21:12:08 +0000

IEEE International Conference on Robotics and Automation (2017): Design, Modeling and Control of a SMA-Actuated Biomimetic Robot with Novel Functional Skin Anonymous (not verified) Fri, 04/21/2017 - 15:12

[video: https://www.youtube.com/watch?v=53yeHrxy-ck]

Abstract: Traditional colonoscopy requires highly trained personnel to be performed. Additionally, current devices may cause discomfort and carry the risk of perforating the bowel wall. In this paper, a soft three modular section robot is designed, modeled, controlled and tested. Each of the robotic sections has three degrees of freedom, one translation and two rotations. The robot uses a peristaltic motion to translate, inspired by the motion generated by the bowel. The robot uses nine independently controlled Shape Memory Alloy (SMA) springs as its actuators and a novel silicone rubber skin provides the passive recovery force to expand the springs to their original state. It also incorporates three air tubes, one for each section, to provide forced convection reducing the cooling time of the SMA springs. A parametric study on the skin curvature and thickness using Finite Element Analysis (FEA) is performed to maximize traction while providing enough recovery force. A multi-input multi-output (MIMO) controller based on fuzzy control is designed and implemented for each of the sections allowing the robot to achieve any orientation between -90 degree and +90 degree in both pitch and roll in less than 4 seconds with near zero steady state error. Both the peristaltic motion and the orientability of the robot are tested. The robot is able to perform a peristaltic motion with maximum speed of 4 mm/s (24 cm/min) and an average speed of 2:2 cm/min. Each section is also able to follow, with less than 2% overshoot and near zero steady-state error, periodic multi-input squared signals of 25 degrees of amplitude.

Ortega Alcaide, J., Pearson, L., Rentschler, M., "Design, Modeling and Control of a SMA-Actuated Biomimetic Robot with Novel Functional Skin," IEEE International Conference on Robotics and Automation (ICRA), Singapore, June, 2017.

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