Long-Stroke Rolling Diaphragm Actuators For Haptic Display of Forces in Teleoperation

Gruebele, Alexander M.; Frishman, Samuel; Cutkosky, Mark R.

doi:10.1109/lra.2019.2894867

Cited by 10 publications

(5 citation statements)

References 20 publications

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“…Rolling diaphragms have been used in both linear and rotational hard pistons ( 41 , 42 ) to remove energy loss from friction while maintaining a fluid-tight seal ( 43 ), but they have seen limited adoption due to constraints surrounding fabrication of long diaphragms ( 41 ). Methods to create long rolling diaphragms have been proposed, but they are intensive and none are commercially available ( 41 , 44 , 45 ). By heat sealing two layers of thermoplastic polyurethane (TPU) separated by parchment paper, we are able to fabricate rolling diaphragms with arbitrary geometry.…”

Section: Resultsmentioning

confidence: 99%

Programmable soft valves for digital and analog control

Decker

Jiang

Nemitz

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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In soft devices, complex actuation sequences and precise force control typically require hard electronic valves and microcontrollers. Existing designs for entirely soft pneumatic control systems are capable of either digital or analog operation, but not both, and are limited by speed of actuation, range of pressure, time required for fabrication, or loss of power through pull-down resistors. Using the nonlinear mechanics intrinsic to structures composed of soft materials—in this case, by leveraging membrane inversion and tube kinking—two modular soft components are developed: a piston actuator and a bistable pneumatic switch. These two components combine to create valves capable of analog pressure regulation, simplified digital logic, controlled oscillation, nonvolatile memory storage, linear actuation, and interfacing with human users in both digital and analog formats. Three demonstrations showcase the capabilities of systems constructed from these valves: 1) a wearable glove capable of analog control of a soft artificial robotic hand based on input from a human user’s fingers, 2) a human-controlled cushion matrix designed for use in medical care, and 3) an untethered robot which travels a distance dynamically programmed at the time of operation to retrieve an object. This work illustrates pathways for complementary digital and analog control of soft robots using a unified valve design.

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Section: Resultsmentioning

confidence: 99%

Programmable soft valves for digital and analog control

Decker

Jiang

Nemitz

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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“…In this work, we were limited by the materials used to make the rolling diaphragm cylinders to using mineral oil. Further exploration of alternative materials or cylinder designs (e.g., [43]) compatible with less viscous fluids like water is needed in order to address this limitation.…”

Section: Discussionmentioning

confidence: 99%

Vector Field Control Methods for Discretely Variable Passive Robotic Devices

Treadway

Gillespie

2021

IEEE Trans. Robot.

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Passive transmission-based robotic devices are capable of providing motion guidance while ensuring user safety and engagement. To circumvent some of the drawbacks associated with steering continuously variable transmissions based on rolling contacts, we are exploring a class of discretely variable devices, based on brakes and hydrostatic transmissions. Previously available control methods for discretely variable devices were built on velocity fields and only developed to stabilize a 1D target manifold. For n-DOF devices, methods to stabilize target manifolds of dimension 1 to n-1 are of interest. In this paper we contribute constraint field methods that stabilize n-1 dimensional target manifolds while leaving the orthogonal subspace free to the control of the operator. We also contribute force-modulated SDOF velocity fields, which add between 1 and n-2 virtual DOF to the motion of devices whose physical constraints leave one DOF. Control performance is demonstrated in simulation for 3DOF devices capable of imposing 1D or 2D constraints and in experiment for 2DOF devices imposing 1D constraints. Our experimental apparatus features digital hydraulic transmissions that are easily configured for n-dimensional space and capable of imposing constraints of any dimension, thus motivating the contributed methods.

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“… 36 The diaphragm is slightly strechable perpendicular to the rolling direction. 37 The rolling edge

withstands the tensile stress

from fluid pressure p :

38 To achieve both, commercial diaphragms are made from fabric reinforced elastomers for tensile strength and anisotropy, while being flexible and fluid-impermeable. 39 But a positive pressure-differential is required, otherwise the diaphragm forms creases and jams the piston.…”

Section: Methodsmentioning

confidence: 99%

“…At the same time, it needs to be stiff in the vertical direction, to minimize losses from undesired deformation of the rolled edge. 37 , 38…”

Section: Methodsmentioning

confidence: 99%

“…At the same time, it needs to be stiff in the vertical direction, to minimize losses from undesired deformation of the rolled edge. 37,38 As a rotary actuator, the diaphragm requires a more complex, asymmetrical shape conforming to the shell part, compared with the cylindrical shape of a standard rolling diaphragm (Fig. 1b).…”

Section: Diaphragm and Actuator Implementationmentioning

confidence: 99%

See 1 more Smart Citation

A Novel Spider-Inspired Rotary-Rolling Diaphragm Actuator with Linear Torque Characteristic and High Mechanical Efficiency

Hepp

Badri-Spröwitz

2022

Soft Robotics

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We present a novel, fluid-driven rotary-rolling diaphragm actuator with direct rotary output. Its working principle is inspired by the spider leg's hydraulically operated joints and the diaphragm design of rolling diaphragm actuators. The new actuator is fully sealed, shows minimal output torque losses, and minimum friction during operation. Stiction and Coulomb friction are avoided by design. Our proposed mechanism can be used as a compliant actuator in soft robots, or as a stiff transmission device, depending on the fluid and working pressure. The rotary-rolling diaphragm is the defining component of the actuator. The diaphragm is based on silicone rubber, reinforced by a fabric with anisotropic tensile strength characteristics. The diaphragm is custom-designed to follow the actuator's toroidal shape and to ensure the smooth unrolling behavior throughout the stroke. Our actuator outputs a constant torque throughout its stroke compared with monolithic, rotary soft robot actuators with a change in torque. Our design offers a high mechanical efficiency of 95%, compactness, a wide working range of 100°, and a low mechanical complexity from a single chamber.

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Long-Stroke Rolling Diaphragm Actuators For Haptic Display of Forces in Teleoperation

Cited by 10 publications

References 20 publications

Programmable soft valves for digital and analog control

Programmable soft valves for digital and analog control

Vector Field Control Methods for Discretely Variable Passive Robotic Devices

A Novel Spider-Inspired Rotary-Rolling Diaphragm Actuator with Linear Torque Characteristic and High Mechanical Efficiency

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