This page (revision-13) was last changed on 2021-03-01 17:59 by Murray Altheim

This page was created on 2021-02-26 00:09 by Murray Altheim

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At line 1 changed one line
This is the preliminary documentation for the __[KD01]__ robot, a 2 wheel (plus caster) differential drive robot. It shares the same software, chassis components, basic drive train, motor encoders and controllers as the [KR01].
[{Image src='attach/KD01/KD01-side.jpg' link='attach/KD01/KD01-side.jpg' width='400' caption='KD01 side view (click to enlarge)' align='right' class='imgFloatRight'}]
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!! Description
This page describes the __[KD01]__ robot, a 2 wheel (plus caster) __differential drive__ robot. It shares the same software, chassis components, basic drive train, motor encoders and controllers as the [KR01].
At line 5 added 17 lines
! Description
The [KR01] robot is still under development, and as an experimental platform it is performing admirably.
[{Image src='https://robots.org.nz/wp-content/uploads/2021/02/kd01-plan-1881.jpg' link='https://robots.org.nz/wp-content/uploads/2021/02/kd01-plan-1881.jpg' width='400' caption='KD01 planning (click to enlarge)' align='right' class='imgFloatRight'}]
As it has no rotational steering like a car (i.e., its wheels are always facing perpendicular to the central axis of the robot), turning involves creating a difference in speed of either its port or starboard motors. Turning therefore requires wheel slippage. At an extreme, if the robot's wheels where so sticky that it couldn't slip over the surface of the ground, the robot couldn't turn at all. When the robot is on, say, a wooden floor, there is a noticeable shudder as its wheels alternately and unpredictably stick and un-stick from the surface, whereas on a dry wooden deck, on grass or dirt this wouldn't much of a problem.
So one limitation with its four wheel design — where the two motors on each side of the robot are wired in parallel to the motor controller — is that it has difficulty rotating in place when on any surface that provides significant friction for its silicon tires. When attempting to perform precise navigation on smooth indoor floors the KR01 is not really very well suited.
Hence the desire to build a differential drive robot.
...more later.
!! Available Media
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[{Image src='https://service.robots.org.nz/wiki/attach/GPIO/raspberry-pi-pinout.png' width='900' caption='GPIO pins on a Raspberry Pi A+' align='center'}]
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| __5__: ext clock (from Itsy Bitsy) | %%grn GND %%
| __6__: rosd toggle switch | __12__: __Button A on 1.14" Mini Pi TFT Display__
| __5__: ext clock (grey, from Itsy Bitsy) | %%grn GND %%
| __6__: rosd toggle switch (orange) | __12__: PWM IRQ (TEMP)
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| __19__: | __16__:
| __26__: (unused: conflict with SPI) | __20__:
| __19__: | __16__: __Button A on 1.14" Mini Pi TFT Display__ (white/blue)
| __26__: (unused: conflict with SPI) | __20__: __Mast IR__
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! Links
* [Differential Wheeled Robot|https://en.wikipedia.org/wiki/Differential_wheeled_robot] on Wikipedia