Presentation on theme: "Telescoping Mast Design Options Presented by Doug Eddy, GRA and Dr. Sundar Krishnamurty at UMass Amherst For Hoppe Tool."— Presentation transcript:
Telescoping Mast Design Options Presented by Doug Eddy, GRA and Dr. Sundar Krishnamurty at UMass Amherst For Hoppe Tool
Lifting Mechanism Design Alternatives Cables on Pulleys with simultaneous lift Roller Chain on Sprockets Straps on Pins Screw Driven Other less proven risky alternatives: Rack and Pinion Linear Motors
Summary of Key Findings Round tubing 21% and 43% better than square for sway limitation. Round tubing 62% and 68% better than triangular for sway limitation. – Round tubing size availability for the largest section may pose a constraint. Manufacturable process validated for round tubing. Vehicle acceleration moving camera greater than 3” from rest in 1 second will exceed the 20” sway spec if the total tubing weight is approx 132 pounds. – This assumes there are no gaps between the tubes. Aluminum is recommended over stainless steel, because the tubes can be larger with more real estate on the inside.
Concerns and Challenges The 300 pound camera at a fast speed imposes a high tension force on the mechanism components. Can we have simultaneous lifting of all sections w/out mechanisms outside and inside? Is the tension force too high for simultaneous lifting? Keeping all the mechanisms and camera wiring inside the mast poses clearance concerns. Design tradeoff with the dia. size of the pulleys mounted within the bushings. – It does not appear likely we can keep the mast weight under 150 pounds, closer to 300 pounds with internal camera wiring. Must keep the tension close to equal on the 2 belts or straps to prevent binding or one side overloading. Maintenance access with internal components with effects of environment, impact, etc.
Evaluation of Pulleys and Cables for Simultaneous Lift ProsWeightsConsWeights Net Weighted Result Simultaneous lifting for all the sections for speed 6 Lack of free fall prevention 10 Exterior mechanisms needs revision 9 Simplicity for focus on design optimization and root cause of short cable life 8 A cable life solution is still needed 8 Lack of differentiation from the prior design 7 Prototype available for preliminary testing 6 Similar to the Floatograph design 6 -20 2040
Evaluation of Roller Chain Concept ProsWeightsConsWeights Net Weighted Result More mechanically positive for freefall prevention if the chain is inspected. 10 Need a take up tray for the excess chain in one travel direction 8 Much more clearance gap and protection from debris is needed 8 Less friction and better power transmission. 10 Unknown cause of binding on the prototype. 4 Durability 10 Speed 3 Much larger and heavier. 8 Chain inspection is difficult and likely needs 2 chains for balance. 8 cost2 WillBurt has a similar design patented in 1993. 3 Sprockets are staggered on curved surfaces. 3 3344 -11
Evaluation of the Straps on Pins Concept Pros Weights Cons Weights Net Weighted Result Life of strap vs. cables10 Some free fall prevention but less than desired 3 Internal components w compact design10 Extra bushing pin/bearing parts3 Complex details, but CNC manufacturable7 Strap material wear on the take up roll at speed 7 2 straps to balance loading and add a freefall safety feature 5 Potential high friction / power requirement design challenge 6 No apparent similar patents so potential for differentiation w IP protection 5 Speed capability unknown. 5 Currently designed to lift one section at a time. 7 Temperature and other effects on the straps is unknown. 7 3738
Evaluation of Screw Drive Concept ProsWeightsConsWeightsNet Weighted Result Very efficient and mechanically positive. 10 No conceptual prototype yet. 4 Design challenge 8 Minimal gap between the tubes. 10 Development time 8 Possibly the most fail proof and low maintenance option. 10 External cable cat trak or cable coil is needed for camera wiring. 4 Should be much faster than the Stiletto competition. 4 Similar to Stiletto by Will-Burt (w Nycoil) patented in 2001. 5 Antennas use a similar design with a flexible screw. 4 Internal clearance conflict between the mechanism and the camera wiring. 4 The design concept of a screw within another screw has various design challenges. 5 Guarding is needed to protect the5 cabling from the environment. More difficult manufacturability.9 38 52 -14
Other Design Decisions Internal vs. External Cabling Tube Cross Section Shape – Circular – Triangular – Square
Camera Electrical Wiring Internally Routed Vs. Externally Routed Internal ProsWeights Internal ConsWeights Net Weighted Result Better protection of the wiring from 10 More difficult to rapidly coil and uncoil due to tight clearance. 8 the harsh operating environment More compact and transportable design 8 Difficult challenge to ensure cabling will never get caught in mechanisms during the rapid retract. 10 Lack of options for external mechanisms given the harsh environment. 7 Lack of real estate for a take up roll mechanism without encroaching on the cockpit real estate. 7 Loss of opportunity for a more efficient and effective internal mechanism design. 8 2533 -8
Cross Section Analysis of Circular Tubing vs. Square or Triangular Circular ProsWeightsCircular ConsWeights Net Weighted Result Better stiffness and strength per weight and cost of material 8 A feature is needed to prevent rotating motion 4 Capability of more accurate alignment by machining bushings on a Lathe 7 Additional bushing components are needed, but they can be multifunctional 6 1510 5
Work to be Done 1) Analysis of scaled down proof of design concept prototypes by the students - completed 2) Evaluation of student designs and research of any other possible options - completed 3) Development and/or modification for optimization 4) Identification of Critical Function Features & a Quality Control Plan 5) Design for Manufacturability and Assembly (DFMA) 6) Theoretical Design Validation to enable a prototype build and test at Hoppe Tool 7) Provide support for life testing and subassembly testing for construction 8) Geometric Dimensioning and Tolerance (GD&T) analysis 9) Completion of prints/specifications for manufacturing at Hoppe Tool 10) Provide support for the first Beta Manufacturing Validation Testing build 11) Refinement, modifications and improvements based on results