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Physically-based Modeling of Motion Pattern for Scorpion Robot
- 2. Overview ! What-is-the-Scorpion-Project? " The-scorpion-is-an-eight)legged-robot-which-carries- many-uses.-Here-at-the-BioVis-Tech-Center,-we-are- trying-to-create-a-model-of-the-robot-that-accurately- demonstrates-its-motion-pattern.-We-are-doing-this-by- examining-the-data-from-the-real-model-and-comparing-it- to-the-data-of-the-simulation. ! What-NASA-expects-to-accomplish-with-it " The-scorpion-has-many-added-functions-of-mobility-that- normal-wheeled-vehicles-do-not-have.-It-can-walk-over- complex-terrain-without-a-problem-and-can-be-remotely- controlled-to-reach-its-destination.-NASA-hopes-to-fully- utilize-these-functions-of-the-scorpion.-- ! The-Motion-pattern-algorithm " The-legs-move-in-an-out)of)phase-manner.-When-one- leg-is-“swinging,”-the-other-seven-legs-are-in-stance,-i.e.- they-are-not-moving.-The-robot’s-motion-pattern-are- based-on-the-following-parameters:-phase,-swing,-and- stance
- 3. Methods-of-Comparing-Simulated- and-Real-Models ! Current,-torque-and-joint- angles-were-extracted-from-the- simulation-and-the-real- models.- ! Both-Models-used-a-very- simple-procedure-to-retrieve- these-values ! From-the-data-values,-graphs- of-each-were-plotted-against- time Figure-1
- 4. Real-Model-Data-Extraction ! The-scorpion-was-connected-to-a-computer-program-that- sampled-data-at-rates-between-1-Hz-and-10-Hz. ! Data-(current-and-angle-values)-were-extracted-from-the- robot-and-were-recorded-in-an-ASCI-text-file.--Later,-the- data-was-converted-into-a-3d-matrix-to-be-used-in- Matlab.- ! The-matrix-was-arranged-as-follows:--n-x-8-x-3-(n-being- the-total-number-of-samples,-8-being-the-number-of-legs,- and-3-being-the-number-of-motors-on-each-leg)
- 5. Simulation-Model-Data-Extraction ! The-simulation-was-created-using-the-Arachi-Dynamics-Engine.- Arachi-is-a-privately-held-California-corporation-dedicated-in- developing-comprehensive-dynamic-motion-technology.-The-current- version-of-this-software-package-provides-a-basic-model-of-the- scorpion-using-simple,-primitive-shapes.-Below-are-the-basic-steps- taken-to-extract-data-from-the-model:- # A-simple-fprintf statement-was-inserted-into-the-motion-pattern-algorithm- code.- # It-sends-the-data-(torque-and-angle-values)-for-each-leg-to-a-specified- file-output-stream,-in-the-order-the-legs-are-moving. # Three-text-files-are-used-to-record-the-data,-one-file-for-each-of-the- following-leg-segments:-Thoracic,-Basalar,-and-Distal.- # The-text-file-contains-the-torque-and-joint-data-for-all-eight-legs- according-to-the-segment-of-the-leg.
- 6. Algorithms # Algorithm-used-in-real-model # The-real-model-uses-a-type-of-pattern-generator-to-execute- the-motion-pattern-of-the-scorpion.-This-pattern-generator- relies-solely-on-the-frequency-of-steps.-It-then-determines- how-to-move-the-thoracic-and-basalar-joints-while-moving.-- In-addition,-the-distal-joint-is-not-involved,-however-it-is- always-at-a-right-angle-to-the-ground.- # Algorithm-used-in-simulated-model # The-simulated-model-calculates-the-angles-for-each-joint- using-inverse-kinematics.-It-takes-the-lengths-specified-for- each-leg-segment-and-the-position-that-segment-needs-to- be-at,-plugs-it-into-a-sin)amplitude-function,-and-returns-and- stores-its-position-at-that-time.-It-also-implements-the- “Swing-and-Stance”-Technique-(shown-in-Figure-3),-which- has-the-legs-follow-the-above-pattern-in-Figure-2-in-an-out) of)phase-fashion.- Figure-2 Figure-3
- 7. Model&Processing From-the-fully)developed,-basic-model-of-the-scorpion-in-Arachi,-we-now-have-a- blueprint-of-the-scorpion’s-structure-that-can-be-translated-into-a-high-resolution- model.-So-not-only-does-the-simulation-behave-like-the-real-model,-it-also-looks- exactly-like-it.-Arachi-currently-is-in-the-process-of-creating-a-new-debug-viewer- that-can-handle-the-high-resolution-3D-models-that-have-been-created-for-it.-A- progression-of-the-steps-taken-have-been-outlined-below: ! Real-Model ! Basic-3D-Model-in-Arachi ! High-Resolution-3D-Model-in-SolidWorks ! High-Resolution-Model-Overlay
- 12. Real-Model
- 13. Simulated-Model
- 15. Analysis # Real-Model-Results # From-this-model,-we-can-see-that-the-scorpion-is-very-efficient-in- terms-of-power-consumption.-This-is-shown-from-the-constant- change-in-the-motor-angles.- # Theoretical-Model-Results # This-model-was-derived-from-real-model-angle-data-and-the- theoretical-torque-equations-used-in-the-control-mechanism-of- the-robot.- # Simulated-Model-Results # Arachi-is-calculating-torques-similar-to-the-way-the-robot-does-but- the-amount-of-torque-required-in-Arachi-is-much-more-than-in-the- real-model.-Furthermore,--the-angular-position-of-the-joints-follow- a-perfect-sine-wave,-whereas-in-the-real-model,-“Swing-and- Stance”-have-two-different-slopes.-