An official website of the United States government
Abstract While soft robots enjoy the benefits of high adaptability and safety, their inherent flexibility makes them suffer from low load-carrying capacity and motion precision, which limits their applications to a broader range of fields. To address this problem, we propose a novel compliant hinge joint with a stiff backbone for load-carrying coupled with soft pneumatic networks (PneuNets) bending actuators. We derive a pseudo-rigid-body model of the joint design and validate it through experiments and simulations. The results show that the joint can achieve a large range of bending angles. The off-axis stiffness is from 16.74 to 627.63 times the in-axis stiffness. This design can carry a heavy load off-axis while maintaining the in-axis flexibility. This work lays out the foundation for designing high-performance soft robots by combining various flexure mechanisms and pneumatic bending actuators.
more »
« less
Semi-Physical Modeling of Soft Pneumatic Actuators With Stiffness Tuning
Abstract The inherent low stiffness in soft robots makes them preferable for working in close proximity to humans. However, having this low stiffness creates challenges when operating in terms of control and sensitivity to disturbances. To alleviate this issue, soft robots often have built-in stiffness tuning mechanisms that allow for controlled increases in stiffness. Additionally, redundant pneumatic manipulators can utilize antagonistic pressure to achieve identical positions under increased stiffness. In this paper, we develop a model to predict the stiffness and configuration of a pneumatic soft manipulator under different pressure inputs and external forces. The model is developed based on the physical characteristics of a soft manipulator while enabling efficient parameter estimation and computation. The efficacy of the modeling approach is supported via experimental results.
more »
« less
- Award ID(s):
- 2024649
- PAR ID:
- 10540249
- Publisher / Repository:
- ASME
- Date Published:
- Journal Name:
- ASME Letters in Dynamic Systems and Control
- Volume:
- 3
- Issue:
- 4
- ISSN:
- 2689-6117
- Page Range / eLocation ID:
- 041006
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
This work presents a unique approach to the design, fabrication, and characterization of paper-based origami robotic systems consisting of stackable pneumatic actuators. These paper-based actuators (PBAs) use materials with high elastic modulus-to-mass ratios, accordion-like structures, and direct coupling with pneumatic pressure for extension and bending. The study contributes to the scientific and engineering understanding of foldable components under applied pneumatic pressure by constructing stretchable and flexible structures with intrinsically nonstretchable materials. Experiments showed that a PBA possesses a power-to-mass ratio greater than 80 W/kg, which is more than four times that of human muscle. This work also illustrates the stackability and functionality of PBAs by two prototypes: a parallel manipulator and a legged locomotor. The manipulator consisting of an array of PBAs can bend in a specific direction with the corresponding actuator inflated. In addition, the stacked actuators in the manipulator can rotate in opposite directions to compensate for relative rotation at the ends of each actuator to work in parallel and manipulate the platform. The locomotor rotates the PBAs to apply and release contact between the feet and the ground. Furthermore, a numerical model developed in this work predicts the mechanical performance of these inflatable actuators as a function of dimensional specifications and folding patterns. Overall, we use stacked origami actuators to implement functionalities of manipulation, gripping, and locomotion as conventional robotic systems. Future origami robots made of paper-like materials may be suitable for single use in contaminated or unstructured environments or low-cost educational materials.more » « less
-
Abstract Variable impedance of upper limbs is critical for multifaceted daily activities, adapting to varying physical environments, and facilitating social interactions. Existing soft wearable robots predominantly focus on stiffness modulation, with minimal attention to damping adjustment. In this study, we introduce a novel soft pneumatic actuator integrated with shape memory alloys (SMAs) to achieve significant damping modulation with minimal stiffness variation. By controlling the SMA temperature, the damping of the actuator can be modulated, as demonstrated by experimental evaluations. Under ideal conditions, results showed a maximum damping increase of 140.9% and a maximum decrease of 91.7%, with a maximum stiffness change of only 8%. Phantom arm demonstrations showed up to 76.2% increase in damping ratio, significantly reducing joint oscillation settling times.more » « less
-
Soft continuum manipulators, inspired by squid tentacles and elephant trunks, show promise in allowing robots to safely interact with complex environments. One ongoing problem for these manipulators is torsional stiffness, as continuum manipulators are naturally compliant and cannot actively resist torsional strain. A hybrid actuator that combines molded silicone actuators with 3D printed flexible wave springs is used to overcome this problem. It is shown that the inclusion of the 3D printed wave spring increases actuator torsional stiffness by up to a factor of 10. Further investigation of these structures is performed using both experimentation and simulation. Finally, this hybrid actuator design is used to create a nine‐degree‐of‐freedom soft continuum manipulator, which is used to perform a cantilevered pick‐and‐place task impossible for a traditional soft manipulator of similar size.more » « less
-
Shape change enables new capabilities for robots. One class of robots capable of dramatic shape change is soft growing “vine” robots. These robots usually feature global actuation methods for bending that limit them to simple, constant-curvature shapes. Achieving more complex “multi-bend” configurations has also been explored but requires choosing the desired configuration ahead of time, exploiting contact with the environment to maintain previous bends, or using pneumatic actuation for shape locking. In this paper, we present a novel design that enables passive, on-demand shape locking. Our design leverages a passive tip mount to apply hook-and-loop fasteners that hold bends without any pneumatic or electrical input. We characterize the robot's kinematics and ability to hold locked bends. We also experimentally evaluate the effect of hook-and-loop fasteners on beam and joint stiffness. Finally, we demonstrate our proof-of-concept prototype in 2D. Our passive shape locking design is a step towards easily reconfigurable robots that are lightweight, low-cost, and low-power.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1115/1.4064090
