lightweight autonomous bot build - Page 3 - The Combine Forum
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post #21 of 41 (permalink) Old 10-07-2018, 04:52 PM Thread Starter
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Quick test of the motor



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post #22 of 41 (permalink) Old 10-07-2018, 07:59 PM
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Did you consider using an actuator with feed back for steering? It would make life so much easier than trying to mount a wheel angle sensor.


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post #23 of 41 (permalink) Old 10-08-2018, 01:14 AM Thread Starter
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Yeah I did try to get an actuator with feedback but the only one I could find in the UK was way too slow. Also the relationship between the stroke length and the angle is not linear (not sure how to explain this without pictures) thinking on it again I don't think it would have been as big of a problem as I initially thought. Now I know the length of ram I need and the rough speed I need I might try and order one from AliExpress with feedback.
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post #24 of 41 (permalink) Old 10-08-2018, 01:32 AM
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No need for pictures, I know what you mean. To keep things linear is just a matter of keeping the distances of the ends of the actuator equal and adjusting those distances to get the speed you need. I have a couple of FB actuators, all slow although not much difference between non FB actuators. The one plus(or negative) is you are doing a rear steer. Generally you do not need as much travel on the steer compared to front steer so a slow actuator would be to your benefit. If you want a good supplier from Aliexpess, pm me. I don't like advertising or endorsing particular suppliers in case something goes wrong.

You get what you put in and people get what the deserve. - Kid Rock

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If it is broken, fix it. If it isn't broken, I'll soon fix that.
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post #25 of 41 (permalink) Old 10-08-2018, 02:15 AM
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why not taking a actuatur with feedback like

https://www.pololu.com/product/2311

if you are using a pololu jrk2g like me your steering would be complete...

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post #26 of 41 (permalink) Old 10-08-2018, 02:40 AM Thread Starter
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The feedback actuator was my original idea, it may be time soon to switch back to the idea as I am making things more complicated than they need to be. I have bought a string potentiometer to play around with so I might need to persevere until I can bring myself to spend more money on this project.
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post #27 of 41 (permalink) Old 10-08-2018, 02:42 AM Thread Starter
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The feedback actuator was my original idea, it may be time soon to switch back to the idea as I am making things more complicated than they need to be. I have bought a string potentiometer to play around with so I might need to persevere until I can bring myself to spend more money on the project.

The main reasons I went against the FB actuator was the lack of choice in speed and stroke length. Also that the linear actuators do not seem to follow the arc of the steering. 1mm of movement depending on the position of the actuator does not always = the same amount of degrees of travel round the arc. The string pot solved this by pulling the string round a circular pulley on the steering.

Last edited by gavztheouch; 10-08-2018 at 02:48 AM.
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post #28 of 41 (permalink) Old 10-08-2018, 02:45 AM
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Keep it simple. I have plenty of experience of making things way to complicated. Stop over thinking things as I think you are on the right track .

You get what you put in and people get what the deserve. - Kid Rock

The more seriously you take things, the harder the rules become.

If it is broken, fix it. If it isn't broken, I'll soon fix that.
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post #29 of 41 (permalink) Old 10-08-2018, 02:50 AM Thread Starter
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Thanks Beerwise. You are definitely right. Please send me the link to the feedback actuator source that you recommend. Many thanks Gav
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post #30 of 41 (permalink) Old 10-08-2018, 03:41 PM Thread Starter
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A small test in the field. Seems to have a decent amount of power for a 200w motor running at half its rated voltage. Plenty of traction as I load up the front Axel by sitting on the machine you can see the back wheel still has grip to push me along. You can see the belt now has a sprung tensioner helping to wrap the belt more around the pulley really helps to prevent the belt skipping teeth.



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Last edited by gavztheouch; 10-08-2018 at 03:44 PM.
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