Building 6 wheeled vehicle

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1

Hello,

Looking at building a 6 wheeled vehicle.
Wheels are 0.17m diameter.
Total max weight 10kg.
1m/s speed.
I have 9ch r/c transmitter and receiver.
Was hoping to use the vex 393 motors.
What esc should I use? And do I need a voltage controller? Or anything else for that matter?

Many thanks in advance

Marcus Hall

3

Hi there,

Welcome on the forum.

According to the specifications of the VEX 393 Motor, the stall current is 4.8A.
This means that it is the maximal current the motor should be able to draw from your Motor Driver.

Note the documentation of the product: https://www.robotshop.com/media/files/zip/documentation-276-2177.zip
The 2-Wire Motor 393 does not have an internal motor controller. The motor connects directly to 2-Wire Motor Ports (Ports 1 & 10 on the Cortex Microcontroller).
Want to go faster than the standard motor but still have the same output torque as the standard motor? No problem! The 2 Wire Motor 393 kit can be configured into a “high speed” version. Simply follow the “Gear Change Procedure” step-by-step instructions to increase the output speed by 60%.
Motor should work at 7.2V

In the best, I would recommend you use the VEX cortex to control the speed of the motor

If you want to go full custom you could also use something like that: https://www.robotshop.com/en/sabertooth-2x5a-rc-driver.html?product-code=RB-Dim-30
Note that this suggestion is probably your best pick since it can be directly connected to the Receiver of your RC system.

Let me know if this helps.

Note that if you want to connect 3 motors in parallel, you will need a stronger driver: https://www.robotshop.com/en/sabertooth-dual-12a-regenerative-motor-driver.html?product-code=RB-Dim-43

4

Hi,

I’m back and been quite busy since we last spoke.

Capture
Capture496Ă—543 395 KB

I have put together a 6 wheeled crawler:
Control:
Standard RC system.

Motors:

DC Geared Motor - 12V 50RPM 50kg.cm

SPECIFICATION

  • Rated voltage: 12 V
  • Gear reduction ratio: 100:1
  • D output shaft diameter: 6 mm
  • No-load speed: 50 RPM @ 12 v
  • No-load current: 0.17 A
  • Rated speed: 45 RPM @ 12 v
  • Current rating: 0.68 A
  • Rated torque: 9 kg.cm
  • Locked-rotor torque: 50 kg.cm
  • Locked-rotor current: 2.19 A
  • Power: 5W
  • Weight: 210 g

Driver:

Sabertooth Dual 12A 6V-24V R/C Regenerative Motor Driver

2nd driver and motor for a scissor lift

SyRen Single 10A DC Motor Driver

Powered from a 18V 2.5ah Ryobi one + battery

Step down DC to DC Step Down Voltage Converter Module

  • Input voltage: 6-28V DC
  • Output voltage: 3-15V DC
  • Max output current: 1.5A
  • Dimensions: 60(L) x 45(W) x 20(D)mm

FPV camera also running off 12V supply.

THE PROBLEM:
I have a voltage display. and when the motors stall e.g. when climbing or screwing around the voltage drops and motors cut out…then voltage comes up again and all good. if I do the climbing or screwing very slowly… very low revs it seems to get by and can slowley power through it and retain a constant power supply.

I thought it might be the amp cut off on the DC-DC converter of 1.5 amp… so I tried a different kind
DC-DC Adjustable Step-Down Module - LM2596 - See MOD0495 IN 4.5-40V (3 amp cut off) but that was worse. In fact the voltage would spike the servos would jump on the FPV camera and the motors would automatically power off in a direction.

I’ll add that I have just (carefully) tested no step down… straight 18V to 12V motors… and there is no issues, obviously motor massively overpowered… but at low throttle they are perfect… and dont stall at all.

PLEASE HELP. I have a project i am going to use this for in a week so ideally I get this sorted before then if it isn’t too much of an issue to actually fix this (including ordering some new part if I have too )

Thanks in advance

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