A simple robot platform

I have a two old Robots 27 mhz band, gears missing teeth etc.
Project is to build a simple new platform two wheels in the centre one castor front and back and able to support say 5kg’s. Robot to be used on flat surfaces moving front and back turning left or right. I wish to use my Spektrum DX6i 6 channel 2.4ghz (aircraft system for my Radian Glider) plus 2x 11V 1300mAh Batteries.
What hardware should i use to create this new platform.
Thanks Robert

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I started to provide an answer to this about 5 times and deleted it each time; realising the question is too broad to provide a concise valid answer.

The answer is anything that works with the very specific items and conditions you have listed.
Can you provide more details related to the specific items you have listed and why they must be used.

I can think of many designs that will do what you want, but the specific items and conditions listed limit the ability to provide a valid answer.

Regards
Jim

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Good Morning and thanks Jim for getting back.

Attached are some photo’s of the Robot that i wish to refurbish, it stands 65 cm H weights 3.5kgs wheel size is 4cm in diameter and 1.5 cm W.

It was suggested that i list the specific items on the forum.

I have searched the internet and visited various hobby shops seeking suggestions, I am confused.

Some weeks ago it was suggested I get on the forum at core electronics and here i am.

Jim looking forward to your suggestion re a simple design to drive the robot and i do not have use the specific items that I have listed.

Thankyou

Robert

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Hi Robert,

Thanks for sending through some more details about what you are trying to do.
Your robot is a bit bigger than the 150 gram RC bot I’ve built but there were some resources that I found super useful which I’m sure can be scaled up.

The Battlebots team Witch Doctor has a series of videos intended to walk beginners through building a 1-pound combat robot and goes over all the calculations needed to ensure each part will work well with the rest of the system. Parts 1 to 5 are most relevant.

There is a more information-dense tutorial by a member of the Bloodsport team aptly titled How to NOT Blow Up Your Robot which covers part selection as well.

For the sake of using the parts you already have it seems sensible 3S LiPo voltage - nominally 11.1V, (if you could confirm that’s what your 11V batteries are) and select gearmotors with an operating voltage of 12V.

From there we just need to select a motor driver or controller based on the current draw of your motors.

Hopefully, this helps get you started, let me know if you have any more questions, it took me a few weeks to get my head around all the parts and how they fit together, but for me the design stage is half the fun.

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Thanks Trent

I will keep in touch.

Robert

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Thanks for the pics, makes a lot more sense.

Your project can be divided into the following parts.

  1. Motors, Batteries, Chassis
  2. Driver board for motors with suitable interface for micro or comms control.
  3. Power supply for electronics.
  4. Communications for remote control.

So, is anything from the old chassis usable ??
The last pic looks like the top has been removed.
From the pic:
2 motors with gearing to wheels (white/green wires and blue/purple wires)
2 rectangular battery packs in series. (red orange/black wires)

Even if motors and batteries don’t work maybe the plastic/metal shell could be used. But trying to make something new fit might not be worth the effort.

From the current motors and batteries the power and torque required can be worked out to drive the robot. Another consideration is how fast the robot is to move and for how long. This will affect the motor gearing and battery capacity.

The following lists some Metal Gear Motors that run from 12V. I have used smaller 5V Metal Gear motors and they are very high quality.

The shaft would directly connect to a wheel because the gearing is inside the motor. The gearing ratio affects the torque and speed. Wheel size would need to be large enough to provide adequate ground clearance. Possibly these motors could be fitted in the current chassis using the current wheels.

What I am saying is there are some decisions to be made as to use the existing chassis or make a new one from scratch or use a different type (Rover 5 Robot Platform or Wild Thumper 6WD Chassis much to expensive IMHO).

Your original post stated 2 wheels and 2 castors. If the gears can be replaced in the original chassis and the motors still work, this might be the best solution.
Plastic gear, maybe a 3D printer could make new gears. (need a friend with a 3D printer)
Metal Gear, maybe a machine shop could make a new one. (probably costly)
In any case further investigation and disassembly of the robot would be needed to see how bad the damage is and how easy to remove and replace.

From scratch, I would get a sheet of Perspex or MDF, and figure out how to attach motors, castors and batteries. Drill some holes, mount some brackets, etc. These would be underneath with the top as the platform. Might not look pretty but it would be a start. Depends on your skills and tools available.

From the Spektrum web site you would need something like the following installed in the robot. I have not looked at what the signal out of the receiver is; it may be able drive a motor board directly, but probably not so a small micro device could be used. It would read the signal from the receiver and switch the motors.
https://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMAR6335#prod_manuals

Further advice really depends on what you decide to do with respect to the chassis.

Regards
Jim

EDIT: Maybe this would be better than an aircraft one. It has steering and throttle.
Possible a 2 or 3 channel one rather than 6 channeds, depends on how much you want the robot to do.

https://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMSR6200A

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