An official website of the United States government
Perching onto objects can allow flying robots to stay at a desired height at low or no cost of energy. This paper presents a novel passive mechanism for aerial perching onto smooth surfaces. This mechanism is made from a bistable mechanism and a soft suction cup. Different from existing designs, it can be easily attached onto and detached from a surface, but it can also hold a large weight when attached to a surface. Further, the mechanism can still work when the suction cup is not precisely aligned with the surface, alleviating the requirement for precise motion control of flying robots. The attachment and detachment are facilitated by the bistable mechanism, while the strong holding is enabled by a locking mechanism that can disable the bistable mechanism. We conduct experiments to characterize the required forces for successful attachments and detachments. We also equip the perching mechanism onto a quadcopter to demonstrate it can be successfully used for perching onto smooth surfaces (e.g., glass).
more »
« less
A Mechanically Intelligent and Passive Gripper for Aerial Perching and Grasping
Perching onto an object (e.g., tree branches) has recently been leveraged for addressing the limited flight time for flying robots. Successful perching needs a mechanical mechanism to damp out the impact and robustly grasp the object. Generally, such a mechanism requires actuation for grasping. In this article, we present a fully passive mechanism without using any actuator: a mechanically intelligent and passive (MIP) gripper that can be used for either aerial perching or grasping. Initially open, the gripper can be closed by the impact force during perching. After closure, if a sufficient mass (e.g., the robot’s mass) is applied, the gripper can switch to a holding state and maintain that state to hold the mass. Once the mass is removed, the gripper can automatically open. We establish static models for the gripper to predict the required forces for successful state transitions. Based on the models, we develop design guidelines for the gripper so that it can be used for different flying robots with different weights. Experiments are conducted to validate the models. Attaching the gripper onto a quadcopter, we demonstrated aerial perching onto rods and aerial grasping rod-like objects. Because the MIP gripper is lightweight (can reach a mass ratio of 0.75% between the gripper and the grasped object for static grasping), we expect it would be well suited for aerial perching or grasping due to the limited payload capability for flying robots.
more »
« less
- Award ID(s):
- 1815476
- PAR ID:
- 10338705
- Date Published:
- Journal Name:
- IEEE/ASME Transactions on Mechatronics
- ISSN:
- 1083-4435
- Page Range / eLocation ID:
- 1 to 11
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Perching significantly enhances the energy efficiency and operational versatility of aerial robots. This article introduces a passive and tunable perching mechanism designed for smooth surfaces. The design features a bistable mechanism (BM) with a soft suction cup, augmented by two sets of shape memory alloy (SMA) actuators for active tuning. The BM enables rapid attachment upon surface contact. A set of SMA wires can increase the BM's triggering force to handle high contact speeds, while a set of SMA springs attached to the suction cup's edges can pull the cup to handle orientation misalignment. Experiments are conducted to characterize how the SMA actuators influence the BM's triggering force and the suction cup's displacement under continuous steady‐state low‐voltage heating. Additional experiments demonstrate fast tuning using momentary high‐voltage heating of the SMA actuators to enhance energy efficiency. The mechanism enables successful perching on smooth surfaces and adapt to varying contact speeds and misalignments when properly tuned for three scenarios: pendulum‐based perching, ground perching, and ceiling perching. With its tuning capability, the perching mechanism can alleviate the need for precise motion control for an aerial robot during perching, expanding the applications of aerial robots in areas like environmental monitoring or infrastructure inspection.more » « less
-
Current aerial robots demonstrate limited interaction capabilities in unstructured environments when compared with their biological counterparts. Some examples include their inability to tolerate collisions and to successfully land or perch on objects of unknown shapes, sizes, and texture. Efforts to include compliance have introduced designs that incorporate external mechanical impact protection at the cost of reduced agility and flight time due to the added weight. In this work, we propose and develop a lightweight, inflatable, soft-bodied aerial robot (SoBAR) that can pneumatically vary its body stiffness to achieve intrinsic collision resilience. Unlike the conventional rigid aerial robots, SoBAR successfully demonstrates its ability to repeatedly endure and recover from collisions in various directions, not only limited to in-plane ones. Furthermore, we exploit its capabilities to demonstrate perching where the three-dimensional collision resilience helps in improving the perching success rates. We also augment SoBAR with a novel hybrid fabric-based bistable (HFB) grasper that can utilize impact energies to perform contact-reactive grasping through rapid shape conforming abilities. We exhaustively study and offer insights into the collision resilience, impact absorption, and manipulation capabilities of SoBAR with the HFB grasper. Finally, we compare the performance of conventional aerial robots with the SoBAR through collision characterizations, grasping identifications, and experimental validations of collision resilience and perching in various scenarios and on differently shaped objects.more » « less
-
Flying robots can exploit perching abilities to position themselves on strategically-chosen locations and monitor the areas of interest from a critical vantage point. Moreover, they can significantly extend their battery life by turning off the propulsion systems when carrying out a surveillance mission. However, unknown disturbances arise from the physical interactions between the robot and the object, making it challenging to stabilize the robot during perching. In this paper, we present a Whole-body Grasping and Perching (WHOPPEr) Drone, which is capable of fast and robust perching by utilizing its entire body as the grasper in lieu of an add-on grasper. We first present the design concept, parameter selection and characterization of the novel whole-body grasping drone. Next, we analyze the grasping ability of the morphing chassis and present an aerodynamic analysis for the effect of motor thrust on the compliant arm. We finally demonstrate, via real-time experiments, the performance of WHOPPEr in autonomous perching and payload delivery tasks.more » « less
-
Robotic grasping can enable mobile vehicles to physically interact with the environment for delivery, repositioning, or landing. However, the requirements for grippers on mobile vehicles differ substantially from those used for conventional manipulation. Specifically, grippers for dynamic mobile robots should be capable of rapid activation, high force density, low power consumption, and minimal computation. In this work, we present a biologically-inspired robotic gripper designed specifically for mobile platforms. This design exploits a bistable shell to achieve “reflexive” activation based on contact with the environment. The mechanism can close its grasp within 0. 12s without any sensing or control. Electrical input power is not required for grasping or holding load. The reflexive gripper utilizes a novel pneumatic design to open its grasp with low power, and the gripper can carry slung loads up to 28 times its weight. This new mechanism, including the kinematics, static behavior, control structure, and fabrication, is described in detail. A proof of concept prototype is designed, built, and tested. Experimental results are used to characterize performance and demonstrate the potential of these methods.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/TMECH.2022.3175649
