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Motivation

Motivation. We wish to test different trajectories on the Stanford Test Track in order to gain insight into the effects of different trajectory parameters on climbing effectiveness, such as: Foot velocity at impact Detachment strategies Velocity & acceleration during pull stroke.

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Motivation

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Presentation Transcript

  1. Motivation • We wish to test different trajectories on the Stanford Test Track in order to gain insight into the effects of different trajectory parameters on climbing effectiveness, such as: • Foot velocity at impact • Detachment strategies • Velocity & acceleration during pull stroke Stanford Test Track • A tool is needed for trajectory generation, allowing for fast, simple iteration and effective control of trajectory.

  2. Requirements • Provide a mechanism for user to specify a trajectory in an intuitive way. • Provide visual feedback of actual 3-D trajectory. • Using inverse kinematics, generate the necessary outputs to run this trajectory on hardware. • Stanford Test Track (motors controlling crank and wing angle) • RiSE platform (motors feeding into differential)

  3. Visual Feedback of Actual 3D Trajectory Overall Procedure Matlab Preprocessor • Initial Trajectory Inputs • Possible Input Methods: • Beta Based Input • Time Based Input Output to Test Track or RiSE

  4. b – Arc length along 2-D trajectory f - Wing Angle y – Crank Angle Test Track 3D Trajectory Climbing direction Lifted from wall Touching wall Wing Angle y Crank Angle b=0 Toe Position

  5. y(Crank Angle) Vs b (arc length on Foot trajectory) Foot trajectory Moving forward y (0~2p) b (0 ~ 1) Mapping between y and b y b . . b y t t

  6. * * * * Defining phases based on b Swing engagement disengagement . swing stroke b f Engagement Disengagement b~0.4 f Stroke b~0.85 Climbing direction b

  7. b – Arc length along 2-D trajectory f - Wing Angle y – Crank Angle Foot Detachment: b ~ 0.85 Foot Detachment Foot Contact: b ~ 0.50 Foot Contact Input Method 1 (Beta Based) . User specified b(db/dt) vs b and f vs b • Current system we are using • Specify desired number and location of input points • Approximate functions using Fourier Series Advantage: Intuitive way of specifying point velocity (b) and wing angle (f) at a specific toe position (b) Disadvantage: Difficult to define input values at a specific time (t) .

  8. b – Arc length along 2-D trajectory f - Wing Angle y – Crank Angle Input Method 2 (Time Based) User specified b vs t and f vs t • 4 phases - quintic splines (matched end conditions) Advantages: • Exact Trajectory with explicit constraints on maximum b and b • Control over accelerations in task coordinates Disadvantage: • Difficult to define parameters at a specific toe position (b) . . .

  9. b – Arc length along 2-D trajectory f- Wing Angle y – Crank Angle Mapping Procedure of Current System(library of Matlab functions) • Configuration File • User Inputs • Link lengths • Gear ratios of differential Initial Inputs Test Track Output RiSE Output

  10. b– Arc length along 2-D trajectory f – Wing Angle y – Crank Angle q1 – Rotation angle of Motor 1 q2– Rotation angle of Motor 2 Summary • Matlab preprocessor • Allows for testing different leg trajectories to find better trajectory for climbing • Input: b(db/dt) vs b and f vs b • Mapping Method • Fourier Curve Fit • Inverse Kinematics • Interpolation • Output • Test Track input: y vs t and f vs t • RiSE input: q1 vs t and q2 vs t .

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