"Tank steering"
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Hi
My DiddyBorg has a custom chassis rather than the official PiBorg one. So the motors are about an inch further apart along their axes, and about a half inch further apart between their spindles.
I've found that it doesn't "tank steer" very well on grippy surfaces like carpet. That is, if I set the opposing wheels to rotate in different directions, I want the whole platform to rotate about its axis (more or less). It does tank steer OK on wood and tile floors. But on carpet it tends to judder and rotate unevenly.
Does the stock DiddyBorg tank steer perfectly on grippy surfaces? It's possible that wheel alignment is not perfect -- I don't have CNC machining facilities in my garden shed :) But I don't want to spend a lot of time fiddling with it if the problem would still be there even if it were perfect.
Best wishes
Kevin
piborg
Tue, 03/08/2016 - 11:17
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Tank steering trouble
The stock DiddyBorg does work on carpet, here is an example:
I imagine the problem is the ratio between the width of your robot and his length.
A really wide distance between the wheels but a short distance from front to back will tank steer very easily.
A really narrow distance between the wheels with a long distance from front to back will find tank steering very difficult.
I would suggest trying to moving the wheels even further apart by an inch or two and see if that makes tank steering behave.
lars_the_bear
Tue, 03/08/2016 - 11:27
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Hi
Hi
Thanks. In the video you posted, were the motors running at full voltage when making those turning manoeuvres? I can get it to work with enough drive, although it's still a bit jerky. My wheels are already ten inches apart (side to side) and there's only about a half-inch clearance between the tyres, so I don't think the width is the problem. I think my platform is quite a bit heavier than yours, which might be a contributing factor.
Best wishes
Kevin
piborg
Tue, 03/08/2016 - 12:46
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Tank steering
I think that the motors were running at the full 6V in that bit of the video.
Carrying more weight does make tank steering more difficult.
What you could do if you do not need the robot to sit completely flat is make the center wheels lower by a small amount, say 5mm.
This will reduce the amount of torque moving forward and backward, but it should make turning easier.
lars_the_bear
Tue, 03/08/2016 - 13:08
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Thanks. I need all the torque
Thanks. I need all the torque I can get :)I think the Mark II will need bigger motors, or a lighter chassis.