Lessons Learned The most important lessons learned Budgets
Lessons Learned • The most important lessons learned. ® Budgets should always be closely monitored and even they tend to be adjusted and changed ® Be quick to react to changing requirements ® The best engineers never get attached to designs, they can scrap and finish a project no matter the issues and set back are part of the norm ® The problem is never fully finished – I constantly wanted to fix problems but had to limit myself to getting the project to a stable point, there is always an issue that can be better but sometimes you have to cut your losses ® Even if you are not the sole lead of a project it is never a bad idea to push other to achieve the set goals, it’s a team project ® It pays to ask other for help, suspension systems are not easy finding individuals to help you with ideas pay off ten fold ® Trust your gut, people may tell you what the “norm” is for a certain application, but do research, why is that the “norm”. In some situations (like mine) it didn’t make sense so I questioned it and formulated a new set of ideas ® Have good problem solving skills, I came in with exceptional mechanical skills, from welding to rebuilding small electronics, and you never know when those will come in handy ® Always stay curious, sometimes the best ideas come from just looking at old ideas ® Lastly, don’t ever rule out a possibility till its been tried, sometimes the ‘dumbest” ideas can pay off © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 1
M. A. R. S. U. P. I. A. L. Mechanical Improvements • Problems ® Leading Incline is too steep ® Overall height may be too high – Raised CG ® Self Leveling issues ® Horizontal spring to stiff ® Air shocks cant handle the cold ® Reverse direction of tensioning ® Track friction – Too high inside – Too low outside ® Size of lower idler wheels © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 2
Leading Incline/Overall Height • Remedies ® Lower leading wheels ® Lower overall height • Benefits ® Aids climbing over objects – Allows for ease of the first idler wheel to travel up and over ® Greater speed when traversing obstacles ~67 Deg © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 3
Self Leveling • Cause ® Air spring are constant force meaning they are always in equilibrium • Remedies to existing ® First try was to add a spring between rod end and shock – Springs were not strong enough and were fully compressed ® Next try is applying large coil spring over entire shock ® Increased spring constant and added spring compressive length • Benefits ® Maintains parallel plane to ground • Remedies for new system ® Added motor inside main Christie – Ability to actively move CG • Benefits ® Actively adjust vehicle baseline ® Actively adjust CG when needed © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 4
Air Spring Problems • Lower tension in horizontal spring • Potentially revert from tension springs to compression • Manage environmental concerns ® Encase the air shock in sealed container © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 5
Direction of Tensioning • W-style active tensioners currently • Two up force tensioners on the outside ® Reduces wrap on motors ® Using torsion for upforce – If too much slack in belt can cause tensioners to flip forwards • Remedies ® M-Style with vertical forces applied – Gives more wrap on the drive wheels – Removes possible over rotation of clock springs © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 6
Track Friction • Full PVC track, steel banded ® Double sided with guiding feature – Thought was to be able to dig into the ground and stair ledges ® PVC had largest friction constant, however this is inside and outside, requiring more than necessary torque to drive • Possible Remedies ® Add nylon facing on inside ® Rethink double sided and instead use higher coeff backing ® Can have machining done to the backing easily for custom profiles © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 7
Possible Backings © 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title page Page 8
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