| ... | ... | @@ -14,49 +14,9 @@ Development of modular, autonomously reconfigurable structures and systems has m |
|
|
|
|
|
|
|
We propose to do the same for materiel, by introducing a new kind of modular, re-configurable robotic system that blurs the boundary between mobile robots and active structures. This is a structural robotic system which is comprised of many agents that, like ants, can interlink to form self-assemblages. Each is constructed from a high-performance structural system that can be reconfigured to realize a range of dynamic forms. Along with spanning gaps, potential applications include novel forms of locomotion, rapidly erecting temporary structures, autonomously adapting to changing requirements, and performing active tasks such as shaping antennas.
|
|
|
|
|
|
|
|
## Evaluation
|
|
|
|
## ZIPPED
|
|
|
|
|
|
|
|
The main task of this project is to develop a modular robotics system with a high strength to weight ratio. Several approaches are explored and evaluated based on the following metrics:
|
|
|
|
|
|
|
|
| Task | Quantification |
|
|
|
|
| --------------------------- | --------------------------- |
|
|
|
|
| Approach | [m/s]/[strength to density] |
|
|
|
|
| Span a gap | [m] of spannable gap |
|
|
|
|
| Strength to weight | [N/kg] of structure |
|
|
|
|
| Reusability and versatility | Qualitative discussion |
|
|
|
|
|
|
|
|
Given each of these tasks the system must perform, and the quantification which will be used to measure the systems success and compare design approaches, there are still many ways to divide the system and complete each task.
|
|
|
|
|
|
|
|
#### Approach
|
|
|
|
|
|
|
|
* The system itself may be able to locomote. Actuators used for the systems construction could double to provide motion of the system on uneven, natural terrain. This could take a leg-like form, such as Theo Jansen’s Strandbeest, or the entire body of the structure could morph into a continuous track allowing it to roll and unfold, as proposed with the Ourobot.
|
|
|
|
* There may be a carrying unit to transport the system to the site. This carrying unit could locomote on uneven, natural terrain as well as the structural robotic construction.
|
|
|
|
* The entire system, or just the carrying unit, may be aerial.
|
|
|
|
* As an alternative to a gait, the robots body could expand and contract locomoting itself in an inchworm manner.
|
|
|
|
|
|
|
|
#### Span a gap
|
|
|
|
* A cantilevered construction can be extended from a single side of the gap. The deflection of a cantilever can be calculated via the following equation, dependent on the materials elasticity, E, and the geometry of the beam, where L is the length of the beam and I is the area moment of inertia.
|
|
|
|
|
|
|
|
<div align="center">
|
|
|
|
<strong> δ=(FL^3)/3EI </strong>
|
|
|
|
</div>
|
|
|
|
<br>
|
|
|
|
|
|
|
|
* A projectile, or aerial unit could place suspension scaffolding. The final structure could either be composed via tensegrity, or this cabling could be a temporary formwork.
|
|
|
|
|
|
|
|
#### Strength to density
|
|
|
|
|
|
|
|
Strength to density is the clearest metric to measure. A structural robotic construction will be weighed, and strength tested on an Instron machine to measure its compressive and tensile strength. It can also be measured with a Charpy impact test to determine the amount of energy absorbed by the material as it fractures. When considering potential construction techniques the forces experienced within different bridge architectures must be considered. Thus, the material system will dictate the geometry of the bridge, and vise-versa.
|
|
|
|
|
|
|
|
The previously mentioned tests are well known methods of materials evaluation used across industry to compare materials, however, rarely are materials selected based on their density. In our application this metric is important for its impact on the first and second metric. For instance, more mass will likely be less efficient to transport.
|
|
|
|
|
|
|
|
#### Reusability and versatility
|
|
|
|
|
|
|
|
Though a truly efficient and reversible system is impossible, as energy must be used to preform work, we aim to design a system which is as reversible and re-usable as possible. Considerations include impact of the system on the environment, material input needed, and energy input needed. For instance, a discussion question used to evaluate and compare systems will be “Can you tell it has passed through a region previously even after it has gone?”
|
|
|
|
|
|
|
|
The system will aim to be self-contained, using the body of the robots as the structure. Therefor parts feeds will be avoided. Material processes that can not be easily reversed, such as composite molding will not be considered. This leaves a limited subset of construction methods including assembly, thermosets and reversible fiber-based processes including weaving and knitting.
|
|
|
|
|
|
|
|
## Method
|
|
|
|
)
|
|
|
|
|
|
|
|
A zipped approach was selected and developed further towards these goals. This system allows isotropic strands of assembled pieces to lock together to form rigid structures.
|
|
|
|
|
| ... | ... | |
