For my Wall-E project, I think I use the modular track system of Lynxmotion with the 3" wide treads and the 12T or 15T sprocket for the rear wheel (and smaller for others). My robot has a cube-shaped body 35 cm wide and weighs about 5 kg. The structure is made with Makerbeam profiles. The robot will move on flat surfaces. Here is the shape of the track that I would like to have : my project thread.
Is this system sufficient for this robot ?
What are all the items I have to buy for this track system ? I think I need one meter of modules per side.
What type of motors should I use? Can continuous servo motors be used ?
What can I use to attach this track system to the Makerbeam profiles ?
Q2) What are all the items I have to buy for this track system ? I think I need one meter of modules per side.
For 3" wide track, you’ll likely need two sprockets per pivot, for a total of 6 per side, 12 in total. The 3" passive idler can be found in the same category, but it’s likely better to use a standard (solid) shaft supported at either end, along with shaft locks of the right diameter. Driving a pair of sprockets side by side won’t be too easy, and you’ll need custom mechanics.
Q3) What type of motors should I use? Can continuous servo motors be used ?
For a 5KG robot (keep in mind the tracks might weight a good percentage of this, and each motor might be 1Kg each), you might start with DC planetary gear motors with a good bit of torque. Use the Drive Motor Sizing Tool to get an initial estimate:
5Kg for a total weight with battery might be low for the size of robot you’re considering.
Q4) What can I use to attach this track system to the Makerbeam profiles ?
That will likely need to be custom-made. Consider investing in a 3D printer.
I used the drive motor sizing tool, and I evaluated the motor specs :
RPM : ~215
Torque : 25 kg.cm
with these characteristics :
Mass : 10kg
Nb motors : 2
Wheel radius : 9cm if I use the higher sprocket of the MTS system.
Velocity : 2m/s
Before I consider buying the track system, I want to be sure the choice of the motors and their controller is good.
For the motors, I think about these :
Q2) I am a developer but not an electronics engineer , are these products compatible with each other (especially for the current) ?
And do you have them on Robotshop France website ? I see the controllers.
Q3) Do you know the difference between these 2 controllers ?
A1) You would need at least two sprockets per axle. The motor you chose has a stall torque of 30Kg-cm, so the dynamic torque is roughly 1/4 that value, only around 7.5Kg-cm, which is far too wear for your application.The other motor has the same issue. No comment on the controllers since the motors are not powerful enough.
A2) The motor 638280 has a stall current of 20A, so you’d need at least a 10A motor controller. The Phidgets controller goes up to 5A continuous, which makes it too weak.
A3) Quite a lot actually - take a look at the “specifications” tab. Note the one in the plastic case is their “next generation”.
A4) Crimps are indeed the way without soldering.
Regarding the motor, you’ll likely need something quite a bit more powerful with a stall torque of 50Kg-cm, or 700oz-in.
If you want 200+ rpm as well, it’s a category of motor RobotShop does not seem to carry.
I didn’t known the difference between the stall and the dynamic torque. I’ll pay attention to that now. But, the Robotshop driving motor size tool estimated me a 25kg.cm torque from my specs. What did I do wrong?
For the RPM, I think the speed I want is too high and not adapted for my robot. I think I can lower it to 0.5m/s. But what is this speed? Empty or loaded ?
I will also recalculate the weight of the robot because 10kg, it seems huge. But it’s true that it can go up quickly with the batteries, wheels, chassis, …
One day, it will succeed to move, this robot !!!
, are these products compatible with each other (especially for the current) ?
