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Origami is an ancient paper folding technique that makes it simple to build and actuate devices ranging from small, scalable, and inexpensive robots to deployable engineering applications. The project describes the creation of a bistable origami-based changeable wheel transformation made by folding sheets of paper coated with various materials. The Waterbomb structure or Magic Air Ball pattern inspired the origami building block structure. We create a support shaft chassis construction with a double rack and a single pinion mechanism that retains the origami-inspired wheel and further modifies its shape. The project also presents a geometrical study of these structures based on linked joints and hinges. MATLAB was used to solve the geometrical equations leading to a range of values under the assumption of given dimensional constraints.
This project lays a groundwork for future research in the field of development of wheel structure for various robotic applications in space targeting mini-scouting rovers which traverse along with a parent rover to the region of interest sites.
Non-rigid Origami or Dynamic Origami has the ability to deform. An example for such origami which plays a huge aspect to this project is the ‘Waterbomb’ structure or the ‘Magic Air Ball’ pattern. The pattern has the capability to deform into sphere or cylinder when force is applied axially or radially.
To change the degrees of freedom of the wheel’s construction, we have used 2 types of facets: stiff and flexible. Following the conventional origami design procedure we have used the same stiffness for our facets and crease lines. Despite the fact that the proposed design loses a significant advantage of tremendous adaptability given by soft materials, it offers us three key advantages.
- The structure can be constructed without the need of numerous mechanical pieces or a time-consuming process. Most parts are replaced by a single sheet, and each joint is generated by a folding part which not only minimizes the cost of manufacture but also the time necessary for assembly.
- In comparison to its weight, an origami structure might have a high rigidity and impact capacity.
- An origami structure is scalable.
A mechanical mechanism commonly used for converting rotary motion into linear motion. The system comprises of two main components: a gear called a pinion and a linear rack. The pinion, which is a small gear with teeth, engages with the rack, a long, flat bar with teeth along its length. When the pinion rotates, it moves the rack in a straight line, creating linear motion.
The compact design of the system makes it ideal for applications with limited space, such as in small vehicles. Furthermore, this system is highly reliable, as it does not require frequent maintenance and has a long service life.
Following are the number of objectives that this project aims to achieve:
- Geometrical analysis for Waterbomb pattern to ensure the dimensions of the structure in its undeformed and transformed state.
- Right material selection for Origami wheel structure for prototyping and perform a comparative analysis of different materials based on their stiffness, flexibility and the ability to deform.
- Force or Load analysis on the wheel structure when subjected to transformation with the help of actuation mechanism.
- Building an actuation mechanism to support the change of magic air ball from compressed state to expanded state.
- Addition of grouser support for extended diameter when expanded.
To study the Geometrical Analysis ⏩ Implementation: Geometrical Analysis
| The flowchart displays a general working of the control aspect of our project where Visual Feedback is ensured to turn the knob of the potentiometer resulting in the change in direction of the servo motor. Apart from this, handheld transformation also took place wherein we pulled the rack while driving on the pinion to provide sufficient torque for the transformation to take place and it was noted that the system would actually work when chosen with the right motor providing more than sufficient torque. |
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| Actuation for Expanded State | Actuation for Compressed State |
Pinion movement is observed which is responsible for driving the rack. It is ensured that the rack traverses along the PCD of the pinion for avoiding any slippage and backslash.
Micro servo motor SG90 having a torque specification as 1.2Kg-cm is clearly insufficient to transform the origami wheel. Force distribution and analysis w.r.t origami wheel was not implemented.Current literature suggests performing compression tests using load cell.
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mech-2.2.mp4
Transformation.mp4
Refer the license for this project here: LICENSE.md