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Comparisons of various drivetrains for FGC 2023

 Comparisons of Drivetrains for FGC 2023


4 Wheel Drive

Advantages:

They have good manoeuvrability and turning.


Disadvantages:

There is less traction because fewer wheels

Less power from motors 


Typically, the front two wheels are Omni wheels for increased turning ability.


6 Wheel Drive

Standard 6-wheel drive:


Advantages:

They have high traction and stability


Disadvantages:

They need more maneuverability and turning.


Two or more motors must be used per side, as splitting one motor over three wheels is horrible.

The motors have to be powered according to the turning and traction

If we use four motors, two motors power two of the middle wheels and the other two can power either the front two or the back two.


An issue that is faced is that the turning could be better. There are two methods to fix this.
1) West Coast drivetrain

-> further explained

2) Corner Omni

-> This is where the corner traction wheels are replaced with omni wheels, which helps to achieve better turning; even though the traction is reduced, it is a valuable sacrifice, as this allows for more traction than 4WD but just as good of a turning



Eight wheel drive



As in 6WD, the centre wheel is dropped to turn better. In 8WD, the four centre wheels are dropped. This allows for the stability and traction of the 6WD with the agility of the 4WD.

The two strategies are 

  1. Powering only the middle motors and letting the corner omnis be free

  2. Powering the middle motors and connecting the corner omnis by chains

The reason to go for this drivetrain is its stability and agility, but this can be tricky to achieve as, without an adequate drop, the turning can be reduced drastically



West Coast Drivetrain


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West Coast drivetrains can be either 6WD or 8WD; however, only the centre wheel(s) is powered. The main point of West Coast drive is that the centre wheel(s) is dropped by around 3-4 mm. This means that only four wheels will ever touch the floor, making turning much more accessible. This is better than a 4WD as the distance between the wheels is far less, allowing the West Coast Drivetrain to turn even easier. By replacing the outer two wheels with omni wheels, turning can be made furthermore accessible.


Advantages:

Have very excellent mobility and maneuverability

Great traction


Disadvantage:

Slightly complicated and challenging to design

Might be too many wheels(in the case of 8WD)



Our Drivetrain Design:


Note: This drivetrain is not meant to be used but just to note some of our first paper scribbles.

(The above image depicts only one side of it)


This drivetrain, called the TriChain Drive, has three motors for power, which are placed at the back of the robot and connected by chain to all the tyres.


Advantages:

All motors power all wheels

All the motors are at the back, which gives more space in the front for storage and shooting mechanisms.

We can make excellent adjustments to gear ratios using chain gears.



Disadvantages:

Requires too many motors.

Having a complex chain system can cause maintenance problems.

The motor mounting could be complex to design.


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