In pursuit of producing robots capable of achieving the dexterity exhibited by animals in nature, roboticists have begun to explore the application of robotic tails. This thesis will explore the design, optimization, construction, and implementation of an articulated serpentine robotic tail. Numerous serpentine tail prototypes have been designed and tested; however, they have not yet been integrated with a mobile base. The main challenges preventing the incorporation of serpentine tails with mobile bases include: (1) the large size and inflexible packaging associated with the actuation unit for the tail, (2) the relatively low power to weight ratios of the existing serpentine tail systems, and (3) the complexity of optimizing the tails physical parameters.
Therefore, to address these issues, a novel layout for a serpentine robotic tail actuation unit along with a design optimization methodology for the tail are proposed. The actuation unit will feature a power dense and modular design which allows for flexibility in packaging. Simulation results along with experimental data gathered using a prototype of the design will be reviewed in order to quantify the performance of the actuation unit. Following, a design optimization methodology which uses a modified direct collocation technique will be presented. The optimization allows for the simultaneous optimization of both a trajectory and the physical structure of a tail. Representative results of this technique will be presented and compared against more traditional methods for design optimization. To conclude the on-going and future work for both the actuation unit and optimization methodology will be stated. / Master of Science / Robotic tails largely fall into two categories based on their construction. These two categories are pendulum and serpentine structure. Pendulum structure tails consist of a long rigid rod with a weight attached to the end of it which can be swung to assist in controlling the orientation of the base which it is attached to. Serpentine tails are characterized by their ability to articulate and move in three dimensions similar to cat or monkey tails. The non-rigid structure of the tail opens up many new possibilities for their use. However, these possibilities come at the cost of design complexity. To date this complexity has led to designs for serpentine tails which are too heavy or unwieldy to be easily added to a mobile base. Additionally, the complexity of the tail structure itself make it difficult to optimize the design as has been done previously with pendulum designs.
In an effort to overcome these challenges this thesis presents a novel design for a tail actuation unit and design optimization methodology. The actuation unit design is more power dense and provides greater flexibility in its layout than previous designs. This makes it much easier to adapt to and integrate with a mobile base. This will be demonstrated through the creation of a prototype tailed quadruped featuring the new actuation unit. The optimization methodology will use a technique known as direct collocation which has previously been developed for optimal path planning. This technique accommodates the complexities of serpentine tail designs and allows for the parameters such as length and weight of the tail to be optimized. The conclusion of the thesis will present the on-going and future work for both the actuation unit and optimization technique.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/111149 |
| Date | 06 July 2022 |
| Creators | Pressgrove, Isaac James |
| Contributors | Mechanical Engineering, Ben-Tzvi, Pinhas, Sandu, Corina, Southward, Steve C. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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