Soft Material Characterization for Robotic Applications

CaseJennifer, C; WhiteEdward, L; KramerRebecca, K

doi:10.1089/soro.2015.0002

Cited by 180 publications

(117 citation statements)

References 34 publications

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“…Although their inherent compliance, easy fabrication, and ability to achieve complex output motions from simple inputs have made soft robots very popular (10,11), there is growing recognition that the development of methods for efficiently designing actuators for particular functions is essential to the advancement of the field. To this end, some research groups have begun focusing their efforts on modeling and characterizing soft actuators (12)(13)(14)(15)(16)(17)(18)(19)(20). In particular, significant progress has been made on solving the forward kinematics problem (16)(17)(18)(19) and even on using dynamic modeling to perform motion planning (14).…”

mentioning

confidence: 99%

Automatic design of fiber-reinforced soft actuators for trajectory matching

Connolly

Walsh

Bertoldi

2016

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

418

266

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Soft actuators are the components responsible for producing motion in soft robots. Although soft actuators have allowed for a variety of innovative applications, there is a need for design tools that can help to efficiently and systematically design actuators for particular functions. Mathematical modeling of soft actuators is an area that is still in its infancy but has the potential to provide quantitative insights into the response of the actuators. These insights can be used to guide actuator design, thus accelerating the design process. Here, we study fluid-powered fiberreinforced actuators, because these have previously been shown to be capable of producing a wide range of motions. We present a design strategy that takes a kinematic trajectory as its input and uses analytical modeling based on nonlinear elasticity and optimization to identify the optimal design parameters for an actuator that will follow this trajectory upon pressurization. We experimentally verify our modeling approach, and finally we demonstrate how the strategy works, by designing actuators that replicate the motion of the index finger and thumb.soft robotics | fiber-reinforced actuators | customized actuators I n the field of robotics, it is essential to understand how to design a robot such that it can perform a particular motion for a target application. For example, this robot could be a robot arm that moves along a certain path or a wearable robot that assists with motion of a limb. For conventional hard robots, methods have been developed to describe the forward kinematics (i.e., for given actuator inputs, what will the configuration of the robot be) and inverse kinematics (i.e., for a desired configuration of the robot, what should the actuator inputs be) (1-4).Recently, there has been significant progress in the field of soft robotics, with the development of many soft grippers (5, 6), locomotion robots (7,8), and assistive devices (9). Although their inherent compliance, easy fabrication, and ability to achieve complex output motions from simple inputs have made soft robots very popular (10, 11), there is growing recognition that the development of methods for efficiently designing actuators for particular functions is essential to the advancement of the field. To this end, some research groups have begun focusing their efforts on modeling and characterizing soft actuators (12-20). In particular, significant progress has been made on solving the forward kinematics problem (16-19) and even on using dynamic modeling to perform motion planning (14). However, the practical problem of designing a soft actuator to achieve a particular motion remains an issue. Finite element (FE) analysis has previously been used as a design tool to find the optimal geometric parameters for a soft pneumatic actuator, given some design criteria (15). Although this procedure yields some nice results, only basic motions (linear or bending) were studied, because the method is computationally intensive. An alternative approach is to use analytical modeling...

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mentioning

confidence: 99%

Automatic design of fiber-reinforced soft actuators for trajectory matching

Connolly

Walsh

Bertoldi

2016

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

418

266

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“…We measured the sensor's response to two different modes of strain: linear extension and pneumatic actuation ( Figure 6). For the linear extension tests, we pulled the tip of the robot arm linearly away from the body of the robot, duplicating a load similar to that of a normal strain gauge [22]. We then used a hand pump to pneumatically actuate the robot in steps while taking profile photographs of the arm, which we analyzed to measure the length change of the liquid metal sensors.…”

Section: Sensor Characterizationmentioning

confidence: 99%

Monolithic fabrication of sensors and actuators in a soft robotic gripper

Bilodeau

White

Kramer

2015

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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103

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In this paper, we present a fluidically functionalized soft-bodied robot that integrates both sensing and actuation. Rather than combining these functions as an afterthought, we design sensors and actuators into the robot at the onset, both reducing fabrication complexity and optimizing component interactions. We utilize liquid metal strain sensors and pneumatic actuators embedded into a silicone robotic gripper. The robot's body is formed by curing the silicone in complex 3D printed molds. We show that the liquid metal strain gauges provide a repeatable resistance response during robotic actuation. We further show that, given sufficient control over other timedependent variables, it is possible to determine when the robot begins gripping an object during actuation.

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“…These devices are typically fabricated from soft materials, in particular silicone elastomers which are flexible (Young's modulus <10MPa in the linear regime) and stretchable (elongation at yield of 500%) [1]. While having many beneficial properties, silicone elastomers are difficult to model because they exhibit nonlinear and time-dependent stress-strain behaviors, undergo continuum deformations, and have effectively infinite degrees of freedom [1], [2]. These characteristics make model-based or open-loop control challenging to implement and thus, state feedback information is often necessary to perform positional control of soft actuators.…”

Section: Introductionmentioning

confidence: 99%

Strain sensor-embedded soft pneumatic actuators for extension and bending feedback

Yuen

Kramer‐Bottiglio

Paik

2018

2018 IEEE International Conference on Soft Robotics (RoboSoft)

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Abstract-For soft robots to leave the lab and enter unstructured environments, proprioception is required to understand how interactions in the field affect the soft structure. In this work, we present sensor-embedded soft pneumatic actuators (sSPA) that can observe both extension and bending. The sensors are strain sensitive capacitors, which are bonded to the interior of fiber-reinforced extension actuators on opposing faces. This construction allows extension and bending to be measured by calculating the mean and difference in sensor responses, respectively. The sSPAs are bonded together to form a flat fascicle to increase the force output and prevent buckling under load, and are robust to component failure by incorporating redundancy. In this paper, we discuss the fabrication of the sensors and their subsequent integration into the actuators. We also report the work capacity and sensor response of the sSPA fascicles under extension, bending, and the combination of both modes of deformation. The sensorembedded soft pneumatic actuators presented here will advance the field of soft robotics by enabling closed-loop control of soft robots.

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Soft Material Characterization for Robotic Applications

Cited by 180 publications

References 34 publications

Automatic design of fiber-reinforced soft actuators for trajectory matching

Automatic design of fiber-reinforced soft actuators for trajectory matching

Monolithic fabrication of sensors and actuators in a soft robotic gripper

Strain sensor-embedded soft pneumatic actuators for extension and bending feedback

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