How to climb the ramp in Tipping Point better?

I currently have a robot with small omni wheels, and 2 60 tooth gears to a 36 tooth gear I can climb the ramp, but I struggle, what can I do to fix the issue

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How many motors do you have on your drive?

You should try to put rubber bands on the wheels

And also try to make your bot heavier

Why should they make it heavier, wouldn’t that put more strain on the motors making it even harder to climb?

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We have a 4 motor base, and our robot is quite heavy.

What motor cartridge do you have?

So 4 motor drives usually struggle climbing the ramp one way to fox is switch to 6 motor drive and another option it to gear your drive for a little more torque so like a 1to1 on 200rpm crate this means that you are going to be slower than everyone else but at least you can climb the ramp. Also make sure that your robot isn’t dragging the ground or ramp whe you climb.

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Green motor cartridge (200 RPM)

I would recommend having 6 wheels. The extra contact area makes it far easier to climb than with 4

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Use 6 wheel drive, one wheel with a motor can be connected with gears on both axles and a conveyor belt to save motor use since you can only use 8 motors in total. A 6 wheel drive makes a huge difference to a 4 wheel drive.

There are 2 types of not being able to climb that I have seen. These two are slipping and stalling. If your wheels are still spinning but your robot is not moving up the platform, you are slipping. If your wheels have grip but are not strong enough to climb the platform, you are stalling.

How to fix slipping:

Get more grip. There are 3 main ways of doing this.

  • Add more wheels
    With more wheels, you can get more traction on the ramp. This makes it easier to apply force to the platform, and due to newton’s third law this will help you climb the platform.
  • Use 4in wheels
    If you are currently using 3.25in wheels, I would suggest swapping them to 4in wheels or 2.75in wheels. 3.25in wheels are made from a different material that gives less traction, and thus makes it harder to park.
    Here is a small chart listing the traction coefficients of different wheels (more is better)
    cofbasetype
  • Add more weight
    If you add more weight to your robot, it will make it easier to get traction on the ground as more force is keeping the wheels in contact with the ground.

How to fix stalling:

You need more power to get up the ramp. This can be solved by:

  • Adding more motors to your drive
    By adding more motors to your drive, you increase the amount of force it can produce when moving. This will help drastically, as it allows you to easily park with many goals.
  • Using gear ratios to increase torque
    If you change the gear ratio that connects your motors to your wheel, you can increase and decrease the speed and torque of your wheels. If you spin from a bigger gear to a smaller gear, your speed will increase, but your torque will decrease. If you do the opposite, small gear to big gear, your speed will decrease but your torque will increase. You can use this to find the right ratio between speed and torque so you can be speedy but also have enough power to park.
  • Reduce the amount of force needed to climb
    You can reduce the force needed to climb by reducing the weight you have, or trying to climb with fewer mobile goals. You can also try keeping your motors from being overheated while parking

TLDR: you should identify why you are not able to park, and then you should look at which solutions are available to solve the issue.

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another common issue for slipping is that your center of mass isn’t in the right place. For the purpose of climbing, you want most of the weight to be towards the front of the bot, not the rear.

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Another issue might be that something is touching the ground and making the wheels not touch the platform (for example, ring guards being too low) and thus not letting the robot climb. We had this problem a while back.

If it is not possible to switch to 6 wheels, what are some ways to prevent slipping with a four wheel drive, outside of weight and center of mass. Our setup is currently 4 wheel, 4 in Omni, 200rpm drive. We can easily climb the platform, however we struggle with balancing due to the robot fishtailing when we make minor corrections, what ends of happening is we simply cross to the other side.

Have a button that sets the drivetrain to breaktype hold. Works wonders.

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this is actually very useful for parking. Not sure how much it will help if you don’t have good traction going up the platform, but it makes balancing much easier from a driver standpoint.

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That statement needs some clarification.

If you have plenty of margin in the driving power and motors do not stall, then the potential of the wheels’ slipping is your main concern. The traction force to move robot forward and uphill is roughly proportional to the weight of the robot times the friction coefficient between the wheels and the surface that you are driving on.

In theory, according to the above formula, for a robot of a given weight the number of wheels doesn’t matter in determining the traction force (except that the when you add more wheels you likely to increase robot’s weight). And, if you are right on the edge of the max power that motors could generate, the weight of those extra weight could even cause the motors to overload and will prevent your robot from driving up the platform.

However, when you add more wheels - it increases the area of contact with the surface and decreases the pressure on the surface, which reduces the depth of deformation in the soft foam tiles (and rubber rollers on the wheels) which, in turn, reduces the amount of rolling resistance friction . This lets you use motor power more efficiently, since it doesn’t have to constantly climb “uphill” out of the indentation in the foam tiles that your robot creates by pushing on the ground with its weight.

rolling_resistance_friction.jpg

When you drive on the rigid surface of the platform there is no indentation in the foam, but similar deformation happens with the rubber rollers on the omni wheels.

I feel like the number of wheels is not as important as ensuring that the surface of the rubber rollers on the wheels is clean and provides the best possible grip on both foam tile and the platform surfaces.

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I assume you have front/back wheels tied together using gears for a consolidated drivetrain?

If front wheels are spinning and back wheels stalling out… make the change.

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Yes, we have our gearing tied together with a pinon (small metal gear) in the middle, our front wheels spin until about half way up, then our whole robot stalls.