Mecanum Wheel Type-B__Revision B3.2

Last crawled date: 1 year, 11 months ago

Mecanum wheel type b revision B-3.2

Formats Notes:
asm format = Solid Edge ST5 (GrabCAD insist it's ST4).
x_t format = Parasolid text file.
x_b format = Parasolid binary transmit file.
JT format = JT open CAD format.


A real concept model of a Mecanum wheel with rollers breaking system.
Though incredibly versatile, the standard Mecanum wheel has an unfortunate side effect which reduce its efficiency considerably. It's wide range of mobility is due to the fact that the peripheral rollers translate a portion of the driving motor force into a force perpendicular or at an angle to that produce by the driving motor. This means that large portion of the force in one direction is lost though the translation into a resulting force by the rollers. As an extreme example of this inefficiency, when the platform travel diagonally, only a front and rear opposing wheels are spinning whilst the rollers on the other two wheels cause direct drag that the motors must fight against. (Australasian conference on robotics 27-29 November 2002)
This problem can be solved in a few ways:
1. Controlling the rollers spins (Mecanum wheel type B)
2. Rotating the rollers assembly arm (Mecanum wheel type R)
3. Rotating the spoke (rollers assembly) & control the spinning speed of the rollers (Type BR)
Rotating the main spoke also solve one big headache that is caused by damaged or uneven rollers (erosion damage), however you need to know how much to rotate the spoke & to what direction (CW or CCW). You also need to know when to rotate the spoke. Of course the same is true regarding braking or slowing the rollers spin.
Any change to rollers angle &/or speed is effecting the main vector of the wheel assembly (i.e the direction of the wheel movement), called “off course vector”. There are some other variables like ground condition, speed, load, contact angle etc that will all combine in the shape of OC Vector.
That pesky OCV is the main reason for the complexity of this system. Gyroscopic servo controlling spinning mechanical parts under load… well designing a complex system bottom-up style is what Spaceclaim do best as you can see with your own eyes.
About this specific model:
This one of the early revisions that uses hydro restriction valve as means to control the rollers spin. This system while relatively simple & elegant found to be problematic & did not pass the mechanical simulation stage. It is however the real model with only a few of the system missing. Sensors wiring harness, hub planetary reduction gear & the restriction valve harness & Spokes rotation systems & gear to name a few.
Even so you got about 1800 parts & if you dig a bit into the design you will understand planty.
Hope you like it :)
Nesher Amir