Mobility - PowerPoint PPT Presentation

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Mobility
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Mobility

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  1. Rolling Mobility

  2. What is mobility? • Understanding wheeled and traced mobility • How do I control the motors • How do I steer • How do I know how far I have gone Topics

  3. Mobility: Directed movement of and agent • Characteristics (land) • Max height of traversable step, • Max width of traversable ditch, • Max speed on flat floor, • Max traversable slpe, • Type of terrain traversable • Cement grave, grass, loose sand etc DEFINITIONS

  4. Wheeled vs. tracked

  5. There are several areas of concern • Simplicity vs. complexity • Reliability • Theoretical vs. practical concerns • Can I get the parts? • Is there a backup plan? Needs as Builders

  6. We have already seen the advantages of differentially steered wheels Using a steering wheel allows one drive motor for Steering the Wheels

  7. Toy servos often come with a circuit board which can be modified to steer “left”, “centre” and “right”. Attach servo to “tiller” arm of steering wheel. Alternate steering

  8. Vehicle Weight • Movement causes redistribution • Yaw and Slip • Yaw caused by turning wheel side ways, slip caused by loss of friction with surface • Torque • Caused by Power to axle • Forward/Reverse • Caused by turning of axle due to torque and momentum of vehicle Forces on a Wheel

  9. Yaw of steered wheels • affects grip of wheels on surface • Slip Caused by friction loss • between steered wheels and surface • Vehicle will not make a “true” turn • Can be reduced • (sometimes) by adding weight over steering components • Turning radius is quite wide needing lots of real estate 45 degree turn using 2 steered wheels

  10. “Actual” turn footprint depends on weight distribution and slip Slip will be different on all contacting wheels “Actual” foot print can be reduced by bringing wheels closer together Turns using wheeled differential

  11. Uptake • hauls track up • Dispersed Weight • done by virtue of track pressure • Slip • Caused by friction loss Forces on a Track

  12. Top • Good Traction and Stability • Relatively poor turning radius • Bottom • Reverse characteristics of top arrangement Steering Tracks