© 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title pagePage 1 Lessons Learned The most important lessons learned.  Budgets should always be closely monitored and even then 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 pagePage 2 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 pagePage 3 Leading Incline/Overall Height ~67 Deg 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

© 2014 Carnegie Robotics LLC. Use or disclosure of document data is subject to the restrictions on the title pagePage 4 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 pagePage 5 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 pagePage 6 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 pagePage 7 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 pagePage 8 Possible Backings