Team Vision for System-Level Design PhaseOur team planned to:
- Complete a function decomposition chart for the Robotter
- Brainstorm possible solutions to tackle the lowest level functions
- Combine solutions that will work together into a complete system
- Complete feasibility studies on solutions to verify they can be accomplished
- Select a complete system solution based on criteria selected by the team
We accomplished all of the above with the exception of deciding on a final solution. The reason being that we would like to present our findings to the customer and weigh her input before moving forward with the subsystem design.
The two best bench marking products we found were the Pleurobot, highlighted in the problem definition phase, and Robotter 1.0. We assessed these products in our Pugh Charts, shown in the Concept Selection Section, against our brainstormed ideas to get an idea of how we can improve upon these.
Feasibility: Prototyping, Analysis, Simulation
The above picture is a rough design of what our tail will look like. The tail will consist of 2 of these assemblies with a motor allowing each section to pivot left and right. This left and right motion will create the thrust needed to swim.
Tail Torque Calculation
Using Newtonian Physics and principles of hydrodynamics, an expression for the tail torque can be derived. The above matlab code performs a calculation of the estimated required torque. With this torque, possible motors can be specified for the tail.
We made functioning prototypes of the three leg designs that we came up with. A leg with single axis movement, dual axis movement in the same plane and finally, dual axis in dual plane. We decided to eliminate the dual axis dual plane option because it is more complicated to coordinate movements and it does not resemble an otter.
Leg Motor Sizing
Modeling the motor torque needed to move leg backward while the ‘foot’ is on the ground. This is the worst case leg movement as the mass of the otter body must be taken into account as well.
Preliminary Buoyancy Calculation
Calculation is partially based on the preliminary buoyancy calculations done by team P18229 (Robotter 1.0). In this case the system was modeled as 2 cylinders, one for the torso and one for the tail.
Morphological Chart and Concept Selection
Risk AssessmentA full list of our working risk assessment can be seen here
Design Review MaterialsOur Design Review Slides can be found here
Plans for next phase