High torque / Low speed motor recommendations for the following idea?

[12axe]

Im still bit confused how the potentiometer works, do I need one of these PhidgetInterfaceKits to calibrate it beforehand , or is pretty much plug n play into the controller ?

Also I noticed the connector is 3 wired pin and the sabertooth only uses screw terminals, so how does that work ?

thanks,

snok

[12axe]

Maybe there are other options for potentiometers with screw terminals , if you look at fig 2.1 in manual for sabertooth you will see the one there haa 3 wires instead of pins , it looks pretty big though so maybe its a slider - not sure ?

Could you not just remove the pin connector on the sensor cable / strip / split each wire and screw it into the terminals that way ?

snok

[12axe]

i suppose what confuses me ( based on what you said ) is whether I need a different type of potentiometer in order to wire this up (like a Single Gang / standard ) that obviously is designed to be soldered onto or whether your saying I can do it using the phegs one with the pins connection shown here.

When you say 2 sets then Im assuming you mean the one in figure 2.1 is a dual gang like this so i take it thats sort then I would need to use , and not the phegs ones as clearly Id have to modify the cable cut the wires on one end so one side screwed in, while the other just used the pins.

The reason Im asking is all the analog potentiometers Im seeing all seem to have that pin connection , not the other ring one you can solder onto , although i do see some others like this.

thanks again,

snok

[12axe]

…

[12axe]

Are there any long or immediate drawbacks to using CIM motors if freewheeling around through motor resistance or whatever else ?

I know you dont freewheel robots around so much ,so this is why Im concerned / curious about it .

thanks,

snok

[12axe]

thanks… I still am having trouble grasping the whole POT thing - sigh , i keep forgetting simplest concepts or things so it gets frustrating.

I think one thing confusing me is these no of turns I see , on sites like farnell , does this relate to the number of times a knob can be fully turned before reaching maxium resistance ?

For example if I choose a 10v 10k pot for my 12 v battery and it has 10 turns , does this mean I need to pick one at +5 % resistance
so the wiper voltage is 0.5v ( 0.001 mW )and I dont go over 2.5 v after 5 turns ?

Or does the No of turns simply just mean a single turn pot as opposed to multi turns ( which I assume means it clicks or works more like a combination lock ) ?

snok

[12axe]

I dont get it then , the only 10k 10v on farnells is 1 turn , what is the point in using a resistor at all , I mean its basically just a 2 volt switch then if its just 1 turn at 20% ?

see here

POT, LINEAR, 10K
Track Resistance: 10kohm
Track Taper: Linear
No. of Turns: 1
Shaft Diameter: 6mm
Shaft Length - Metric: 20mm
Resistance Tolerance: ± 20%
Voltage Rating: 10V
Power Rating: 10mW
Potentiometer Mounting: Panel
No. of Gangs: 1
Adjustment Type: Shaft
SVHC: No SVHC (18-Jun-2012)
Bush Diameter: .075mm
Dielectric Strength VAC: 300V
End Resistance: 3ohm
External Depth: 7.1mm
External Length / Height: 11.35mm
External Width: 9.5mm
Mounting Type: Through Hole
Operating Temperature Max: 100°C
Operating Temperature Min: -55°C
Operating Temperature Range: -55°C to +125°C

[12axe]

id be happier with more rather than less for different speed rates rather than being stuck on say 5 and only having 2 ( assuming 3 means off and the 2 below 2.5v are reverse ) it sort of makes me wonder what sort their using on some mobility scooters, as some of the travel ones are only 12 v too.

Ive written to Farnells tech support BTW as im curious what they mean myself.

snok

[12axe]

What do you think of this POT, it mentions it has high torque availability which I can assume can only be a plus given my needs .

snok

[12axe]

Well trying to find a pots that only uses 5% plus 10 turns seems to be quite difficult , do most of the controllers in robotics go in reverse after a dropping below a certain voltage like the 2.5 in the sabertooth ?

Although it would be useful Id rather sacrifice that reverse or be able alter it so the overall voltage was set up to go forwards with 8 turns rather than having 4 of those devoted to reversing speeds I dont need.

I notice on mobility scooters for example they have a separate power button for the battery and one for reversing ( usually a brake lever they push ) which would be more ideal if it wasnt too complicated to do.

The problem with ebike throttles and scooter too is their all twist or thumb so its impossible to keep a steady cruise rate without gripping and holding it in position which is almost impossible for me to do unless I add some adaption (like this one I planned ) so thats why Im not that high in those sorts of controls - far better I have something I can set and leave , and alter at my own choosing.

BTW do those multi turn pots make any clicks or sounds the more or less resistance you use, so you have an idea of far your turning i.e. if Im steering I wont be able to stop and look or mentally remember how far I turned unless I have some speedometer.

Perhaps I can find knob / marked too so I can see ?

snok

[12axe]

yes I realise Im going to have to test this and make some mistakes as theory part isnt easy for brain to take onboard due to my issues , I was just curious any way to save some heartache later or worse disasters .

The other thing that just hit me too was the degree of rotation , I mean if its the full 360 even with 10 turns that is a lot of twisting on my hands , so while I could handle 180 or 230 - 40 ok it would get uncomfortable if im having to turn it a lot over a period of time, so is it standard to have twist all the way round to reach 5 volts or are there ways using something like microcontroller to alter that too i.e. so i only have to turn 180 deg to reach 5v as opposed to 360 or whatever ?

thanks

snok

[12axe]

Its not so much the turn rather than the interval or length of turn between each 5% that the problem because it means I will have to flex my wrist round a lot more ( i.e. 20 turns within 180 no problem , but even 5 over 360 a real pain )

I did look at digikey but theirs only starts at 220 , and even choosing that theres still only 2 I can see at 10k - neither at 5 but 10%- there are none at all for 180 ,so I dont where those mobility folk get them, unless they make them themselves. ?

snok

[12axe]

Can you tell me what the power rating i.e. 2 watts meant to represent on digikey site?

the pots itself only takes 1amp x 5 volts = 5 watts

snok

[12axe]

It says each input on the 5v terminals on the sabertooth can take up to 1 amp ( sorry my mistake ) so Im assuming the safety input is something like 2 or 2.5 watts with 5 being the max ?

snok

[12axe]

can you give an example of what you mean by standard, do you mean a 5 turn , 5% 10k so youd have something like this ?

(0% twist) -> 0 Ohms
(25% twist) -> 2.5k Ohms
(50% twist) -> 5k Ohms
(75% twist) -> 7.5k Ohms
(100% twist) -> 10k Ohms

thanks

snok

[12axe]

I notice your out of CIM motors for now, so I had look around and noticed this site selling gearboxes for Cim too.

Would something like 12:75:1 you think be too much of a reduction for my uses , or would you recommend something lower ?

thanks again,

snok

[12axe]

So am i correct in assuming all I would need is the CIM motor itself , or do I need the sprockets too , and the encoder to convert the signal ?

thanks again,

snok

[12axe]

What do you think about having dual motor setup within the same gearbox like this , as opposed to having one on both wheels ?

Are there any drawbacks or would it allow me more torque at lower speeds ?

m

[12axe]

Just how powerful a controller ( $$$$$ )roughly are we talking ?

I saw this video this video of what loads this thing can handle , and was pretty surprised .

thanks,

snok

[12axe]

Ok the gear set up between the cluster cogs are the same for the the 14:1 ( 14:88:1 ) but cog on the motor itself smaller ( 12 teeth for 14:1 as opposed to 14 for 12:1 )

Does that also mean I could use the other ratios like 12.5:1 I take it as well. ( curious )

snok