Soft Pneumatic Gelatin Actuator for Edible Robotics

We present a fully edible pneumatic actuator based on gelatin-glycerol composite. The actuator is monolithic, fabricated via a molding process, and measures 90 mm in length, 20 mm in width, and 17 mm in thickness. Thanks to the composite mechanical characteristics similar to those of silicone elastomers, the actuator exhibits a bending angle of 170.3 {\deg} and a blocked force of 0.34 N at the applied pressure of 25 kPa. These values are comparable to elastomer based pneumatic actuators. As a validation example, two actuators are integrated to form a gripper capable of handling various objects, highlighting the high performance and applicability of the edible actuator. These edible actuators, combined with other recent edible materials and electronics, could lay the foundation for a new type of edible robots.Comment: Submitted to IEEE/RSJ International Conference on Intelligent Robots and Systems 201

Soft robot design methodology for ‘push-button’ manufacturing

‘Push-button’ or fully automated manufacturing would enable the production of robots with zero intervention from human hands. Realizing this utopia requires a fundamental shift from a sequential (design–materials–manufacturing) to a concurrent design methodology

Hybrid Control Strategy for Force and Precise End Effector Positioning of a Twisted String Actuator

Funding Agency: Swiss Innovation Agency, InnosuissePeer reviewedPostprin

How can human motion prediction increase transparency?

International audienceA major issue in the field of human-robot interaction for assistance to manipulation is transparency. This basic feature qualifies the capacity for a robot to follow human movements without any human-perceptible resistive forces. In this paper we address the issue of human motion prediction in order to increase the transparency of a robotic manipulator. Our aim is not to predict the motion itself, but to study how this prediction can be used to improve the robot transparency. For this purpose, we have designed a setup for performing basic planar manipulation tasks involving movements that are demanded to the subject and thus easily predictible. Moreover, we have developed a general controller which takes a predicted trajectory (recorded from offline free motion experiments) as an input and feeds the robot motors with a weighted sum of three controllers: torque feedforward, variable stiffness control and force feedback control. Subjects were then asked to perform the same task but with or without the robot assistance (which was not visible to the subject), and with several sets of gains for the controller tuning. First results seems to indicate that when a predictive controller with open loop torque feedforward is used, in conjunction with force-feeback control, the interaction forces are minimized. Therefore, the transparency is increased

Robogami: A Fully Integrated Low-Profile Robotic Origami

Intelligent robotic systems that can react to unprogrammed tasks and unforeseen environmental changes require augmented "softness." Robogami, a low-profile origami robot, addresses intrinsic (material-wise) and extrinsic (mechanism-wise) softness with its multi-degree-of-freedom (DOF) body driven by soft actuators. The unique hardware of the Robogami and its submillimeter thick construction enable diverse transformations as those achievable by the paper origami. The presented Robogami shows the first fully integrated version that has all the essential components including its controller within a thin sheet. Construction of this robot is possible via precise, repeatable, and low cost planar fabrication methods often reserved for microscale fabrications. In this research, we aim at expanding the capabilities of Robogamis by embedding bidirectional actuation, sensing, and control circuit. To assess the performance of the proposed sensors and actuators, we report on the performance of these components in a single module and in the four-legged crawler robot

Soft actuation and sensing towards robot-assisted facial rehabilitation

Continuing research efforts in robot-assisted rehabilitation demand more adaptable and inherently soft wearable devices. A wearable rehabilitative device is required to follow the motion of the body and to provide assistive or corrective motions to restore natural movements. Providing the required level of fluidity in wearable devices becomes a challenge for rehabilitation of more sensitive and fragile body parts, such as the face. To address this challenge, we propose a soft actuation method based on a tendon-driven robotic origami (robogami) and a soft sensing method based on a strain gauge with customized stretchable mesh design. The proposed actuation and sensing methods are compatible with the requirements in a facial rehabilitative device. The conformity of robogamis originates from their multiple and redundant degrees of freedom and the controllability of the joint stiffness, which is provided by adjusting the elasticity modulus of an embedded shape memory polymer (SMP) layer. The reconfiguration of the robogami and the trajectory and directional compliance of its end-effector are controlled by modulating the temperatures, hence the stiffness, of the SMP layers. Here we demonstrate this correlation using simulation and experimental results. In this paper, we introduce a thin and highly compliant sensing method for measuring facial movements with a minimal effect on the natural motions. The measurements of the sensors on the healthy side can be used to calculate the required tendon displacement for replicating the natural motion on the paralyzed side of the face in patients suffering from facial palsy

New soft robots really suck: Vacuum-powered systems empower diverse capabilities

We introduce a vacuum-powered soft pneumatic actuator (V-SPA) that leverages a single, shared vacuum power supply and enables complex soft robotic systems with multiple degrees of freedom (DoFs) and diverse functions. In addition to actuation, other utilities enabled by vacuum pressure include gripping and stiffening through granular media jamming, as well as direct suction adhesion to smooth surfaces, for manipulation or vertical fixation. We investigate the performance of the new actuator through direct characterization of a 3-DoF, plug-and-play V-SPA Module built from multiple V-SPAs and demonstrate the integration of different vacuum-enabled capabilities with a continuum-style robot platform outfitted with modular peripheral mechanisms. We show that these different vacuum-powered modules can be combined to achieve a variety of tasks—including multimodal locomotion, object manipulation, and stiffness tuning—to illustrate the utility and viability of vacuum as a singular alternative power source for soft pneumatic robots and not just a peripheral feature in itself. Our results highlight the effectiveness of V-SPAs in providing core soft robot capabilities and facilitating the consolidation of previously disparate subsystems for actuation and various specialized tasks, conducive to improving the compact design efficiency of larger, more complex multifunctional soft robotic systems

Practical control methods for vacuum driven soft actuator modules

Vacuum-powered Soft Pneumatic Actuator (VSPA) Modules have been described to afford advantages for rapid development of reconfigurable, multi-DoF soft pneumatic robots powered by vacuum by reducing their logistical complexity, however they also present new challenges in the control of resulting systems. This framework features modules joined together over a simple embedded pneumatic and serial communication network and requires a unique approach to both low-level control implementation and high-level control strategy. We describe the structure and activation characteristics of a V-SPA Module and present practical methods for its control. These methods utilize software generated PWM activation through a unique serial protocol designed for LED networks and a heuristic mapping strategy for simplifying the spherical control of 3-DoF actuator modules

Trunk postural tracking of assistive soft pneumatic actuator belt

Fiber-reinforced Soft Pneumatic Actuators (SPAs) are found in mobile robots, assistive wearable devices, and rehabilitative technologies. Being intrinsically compliant and readily manufacturable they are attractive for use where safety and customizability are a priority. While different types of SPAs can be found to match the force performance requirements of a variety of applications, outlying system-level issues of robustness, controllability, and repeatability are not traditionally addressed at the actuator level. The SPA pack architecture presented here aims to satisfy these standards of reliability as well as extend the basic performance capabilities of SPAs by borrowing advantages leveraged ubiquitously in biology; namely the structured parallel arrangement of lower power actuators to form the basis of a larger, more powerful actuator module. An SPA pack module consisting of a number of smaller SPAs will be studied using an analytical model and a physical prototype. For a module consisting of four unit actuators an output force over 112 N is measured, while the model indicates the effect of parallel actuator grouping over a geometrically equivalent single SPA scales as an increasing function of the number of individual actuators in the group. A 23% increase in force production over a volumetrically equivalent single SPA is predicted and validated, while further gains appear possible up to 50%, reasonably bounded by practical limitations from material properties and manufacturability. These findings affirm the advantage of utilizing a fascicle structure for high-performance soft robotic applications over existing monolithic SPA designs. An active wearable belt will be presented to demonstrate the capability of SPA pack modules to affect human trunk posture while standing, while further work may enable active modulation of trunk angle during walking to provide corrective assistance or gait modifying perturbations