yes, not sure how this helps you tuning tho
Just curious in the future when I purchase better motors, which I’m thinking of doing soon
2 x pi x radius
or
pi x diameter
is the wheel circumfence. This is how far the wheel travels with one revolution.
Enter radius/diameter in meters.
(2 x pi x radius x rpm)/60
or
(pi x d x rpm)/60
is the ideal speed in m/s. With load, wheelslip and terrain it is usually slower than this.
Be sure to enter output shaft rpm for geared motors.
Thank you for explaining Sebastian.
Well guys I want to say that you was All right about the battery I ordered🤦🏻♂️
It’s bloody huge & weighs over 1KG which unfortunately my rover can’t handle with the weight.
The weird thing is that when I place it on the rear end of the rover it actually moves really well but dead centre it doesn’t move at all.
So I thought either 1: keep the battery & upgrade the standard 12v motors the rover came with, upgrade to something with lots of power & huge torque with a lower rpm like 50-100rpm.
Or 2: keep my current setup & use a smaller battery.
I like the idea of getting better more robust motors to handle rough terrain & slopes etc.
But yes as you all told me it won’t handle a battery of that size. I apologise for my ignorance in not listening to those who gave their advice. @dkemxr @David_Boulanger @iampete
Using one or 2 5000-8000mah batteries would be the logical choice.
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I’m saying nothing 
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Yes, good value with that battery. This would be the largest one I would suggest:
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I have had a very good experience with RMRC batteries. Although at the moment they have a lot back ordered. I have these in 5000 mAh and 8000 mAh capacity which appear no longer being sold. Venom also makes a lite battery designed for the old 3DR Iris which is only 8C, I think, but very light weight. I don’t know what the Amp demand is on your vehicle. The Venom battery is 3S 5000 or 5200 mAh I can’t remember and I’m not where the batteries are right now. Just another option.
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For US buyers (sorry Mus) I have countless charge cycles from 2 rovers on this battery. The size is convenient as it is meant to fit Traxis and other cars/trucks.
http://www.valuehobby.com/power-systems/batteries/3s-lipo/25c-6400mah-3s-trx.html
Good news guys,
Last night I managed to make the rover do a successful auto mission using 2 waypoints.
The first waypoint was straight and the second waypoint was on the opposite end of waypoint 1.
The rover went straight, stopped at waypoint 1, then turned 180* accordingly & came straight back and stopped at waypoint 2.
What I will do next is head to the same car park for some further tuning to see how straight it can go for a longer distance. I was in my living room last night running tests. I did tweak the PID in increments of 0.01 like you suggested & it seems fine.
I’m acro mode the wheels turn as required when the rover is picked up
I would like to purchase some new motors with better torque. @dkemxr you suggested planetary motors but there’s so many here:
http://www.lynxmotion.com/c-71-planetary-motors.aspx
Which ones would be best? I would like the best ones from the list with highest torque & that can produce 0.60 - 1 M/S
My Wheel size: 0.12065 meters
RPM: 50
M/S: 0.6317234
Any help on choosing a solid motor would be appreciated.
@iampete @David_Boulanger @count74
The planetary gear motors come in two sizes 555 and 775. The smaller ones have the same diameter as the motors that came with the rover.
This is the motor I currently have:
http://www.lynxmotion.com/p-93-gear-head-motor-12vdc-301-200rpm-6mm-shaft.aspx
Specifications
- Weight = 5.36 oz (151.95 g)
- Reduction = 30:1
- Stall Torque = 63.89 oz-in (4.6 kg-cm)
- Length (motor and gear) = 1.92" (4.88 cm)
- Length (shaft only) = 0.89" (2.26 cm)
- Diameter (motor and gear) = 1.45" (3.68 cm)
- Diameter (shaft) = 6mm
- Outside Diameter = 37mm
- Current (at 12v no load) = 90mA
- Current (at 12v locked shaft) = 1.5A
This is the motor I was thinking to buy if you all feel it’s suitable:
http://www.lynxmotion.com/p-1079-planetary-gear-motor-pgm36-2691.aspx
- Speed (No load): 3000rpm
- Current (No load)t: 0.18A
- Speed (Max efficiency): 2370rpm
- Current (Max efficiency): 0.67A
- Torque (Max efficiency): 177 g-cm / 2.46 oz-in
- Power (Max efficiency): 4.3W
- Efficiency (Max): 53.4%
- Current (Stall): 2.5A
- Torque (stall): 838g-cm / 11.64 oz-in
Motor w/Gearbox
- Gear Ratio: 26.9:1
- Gears: Metal
- Speed (No load): 107rpm
- Current (No load): 0.2A
- Speed (Max efficiency): 80rpm
- Current (Max efficiency): 0.71A
- Torque (Max efficiency): 3440 g-cm / 47.77 oz-in
- Power (Max efficiency): 2.94W
- Efficiency (Max): 34.7%
- Current (Stall): 2.5A
- Torque (stall): 15600g-cm / 216.64 oz-in
50RPM will not produce .6 m/s with .12m diameter wheels. ~80rpm will do that so I suggest something ~160RPM for maneuvering when not running a mission. Planetary gear motors will be more robust but you will need to choose a motor that will fit that chassis and have the same shaft diameter unless you are willing to do more re-building. Looks like those motors have a 6mm shaft and many Planetery gear motors don’t. The easiest drop-in replacement would be another spur gear motor with lower RPM (120 say) and more torque will be realized just from the gear ratio.
Thank you for explaining. On the planetary motors it doesn’t state the shaft size so it’s probably safer to go for the spur gear motor @120rpm:
http://www.lynxmotion.com/p-94-gear-head-motor-12vdc-501-120rpm-6mm-shaft.aspx
Specifications
- Weight = 5.36 oz (151.95 g)
- Reduction = 50:1
- Stall Torque = 123.20 oz-in (8.87 kg-cm)
- Length (motor and gear) = 1.92" (4.87cm)
- Length (shaft only) = 0.89" (2.26 cm)
- Diameter (motor and gear) = 1.45" (3.68 cm)
- Diameter (shaft) = 6mm
- Outside Diameter = 37mm
- Current (at 12v no load) = 90mA
- Current (at 12v locked shaft) = 1.5A
Would these new motors be able to handle the 20,000mah battery I have or would it still struggle? I will still buy a smaller battery regardless just curious how these would work.
The battery when placed at the rear of the rover works really well, no problems in 360* turns. But when it’s centred it causes it to struggle.
Would these new motors sort that out?
Looks like ~50% more torque so it just might handle the load of that battery. It’s struggling when its center loaded because the load from tire scrub is too great. Unloading the front tires allows it to slip easier. But you don’t want that you will loose the traction you might need in some circumstances. If you only need a max speed of ~0.7 m/s then other than the expense I don’t see a downside to using those motors. No matter what motor though you still don’t want to use that big battery, you will wear everything out.
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Yes I thought the same in regards to losing traction when climbing a small slope or going slightly uphill. The rover would probably flip over.
The torque is 50% higher so it probably will handle it but what would be better is if I purchase these motors and use a smaller size battery. Then it would be even better
Yes, I agree with that but you might want to start with the battery. Your current motors may work fine.
I feel that you really need to get over this idea that one battery of 20,000 mAh is better then four 5000 mAh batteries. Having multiple smaller batteries, although equally charging them becomes more important, is the way to go and will make your life far easier.
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When I had sailboats (big ones, not RC) the saying went “a boat is a hole in the water to put money in”. The same can hold true for Rovers I guess 
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I lived and cruised on 4 different sailboats over a 20 year period of time. If you lived on one the expense was worth it. Otherwise what you said.
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