Truly omnidirectional omniwheels?

[George1902]

Originally Posted by Exotria

...I can't visualize omniwheels working perfectly at a 60 degree angle from the direction they're suppose to roll...

When the robot is moving in the direction of rotation, the wheel rotates and the rollers are stationary on their axes. When the robot is moving perpendicular to the direction of rotation, the rollers rotate and the wheel is stationary on its axis. Any vector in between these produces rotation on both the rollers' axes and the wheel's axis.

[Exotria]

I don't know about your team, but our motors use an autolocking system so that it's harder for us to be pushed. Thus, whenever a motor isn't receiving instructions, it locks itself up, so if certain motors are moving(say, two matching sides in a hex drivetrain design) while others aren't, the wheels wouldn't be rolling to go along with the miniwheels. Omniwheels wouldn't be very omni in that situation. And that's the point of my idea.

[RogerR]

Originally Posted by Exotria

I don't know about your team, but our motors use an autolocking system so that it's harder for us to be pushed. Thus, whenever a motor isn't receiving instructions, it locks itself up, so if certain motors are moving(say, two matching sides in a hex drivetrain design) while others aren't, the wheels wouldn't be rolling to go along with the miniwheels. Omniwheels wouldn't be very omni in that situation. And that's the point of my idea.

the hex drive train that you're talking about would definitely work with traditional omni wheels. you're right about the wheels not being able to free-wheel when the motor is unpowered, but this is a good thing. you want the rollers to only free-wheel in a direction that has another powered wheel opposing it, so that the powered can control motion in that direction. if the rollers swivel, then the drive will be difficult to control, and will have virtually no traction (how much traction does a desk chair get?).

i'm sorry if this doesn't make sense; omni directional drive trains are difficult to explain without delving into vectors trigonometry.

[Alan Anderson]

Originally Posted by Exotria

I don't know about your team, but our motors use an autolocking system so that it's harder for us to be pushed. Thus, whenever a motor isn't receiving instructions, it locks itself up, so if certain motors are moving(say, two matching sides in a hex drivetrain design) while others aren't, the wheels wouldn't be rolling to go along with the miniwheels. Omniwheels wouldn't be very omni in that situation. And that's the point of my idea.

I guess I still don't understand the point. Are you trying to make an omniwheel that rolls freely in every direction? A standard omniwheel does that. Are you trying to make an omniwheel that rolls freely in every direction even when it's prevented from turning around its main axis? That would work exactly against your reason for locking the drive shaft in the first place.

[Mr. Freeman]

I think he wants an "omni"wheel that will roll freely in every single direction except forward/backward. (Thus, the motors will still drive the wheel along one axis.)

With traditional omniwheels you can push them only sideways if the driveshaft isn't moving. With the wheels he's talking about you could still push the wheel at a 45 degree angle with forward being 0 degrees.

It wouldn't have very much traction though, but I think that's the point.

[Exotria]

Yeah, that's what I'm going for. Of course, a more senior team member is telling me I'm dumb, so most likely it won't ever happen. Of course, I can still dream.

The locking of the motors would still have its intended effect because from almost any angle there would be wheels going forward or close enough forward so that the wheels wouldn't let it roll. Or something akin to that.

And Roger, I'm afraid I can't... really visualize your statement of the problems. Someone needs to invent a machine that visualizes thoughts and sticks them on a screen. To be used for purely scientific purposes.

[MasonMM]

Originally Posted by Exotria

Someone needs to invent a machine that visualizes thoughts and sticks them on a screen. To be used for purely scientific purposes.

They have... and i believe it's called microsoft Paint. I can't visualize very well how this differs from a normal omnidrive except that it has 6 wheels... and powering 6 wheels will be a challenge since you dont have 6 identical motors.

[X-Istence]

Originally Posted by MasonMM

They have... and i believe it's called microsoft Paint. I can't visualize very well how this differs from a normal omnidrive except that it has 6 wheels... and powering 6 wheels will be a challenge since you dont have 6 identical motors.

Use 2 motors total, and use two of them to power all 6. We this year had 4 wheels, two motors. One wheel was direct drive from the gearbox, the other was 1:1 ratio chained with the other wheel that was direct driving.

[chrisinmd]

Originally Posted by Exotria

I don't know about your team, but our motors use an autolocking system so that it's harder for us to be pushed. Thus, whenever a motor isn't receiving instructions, it locks itself up, so if certain motors are moving(say, two matching sides in a hex drivetrain design) while others aren't, the wheels wouldn't be rolling to go along with the miniwheels. Omniwheels wouldn't be very omni in that situation. And that's the point of my idea.

Are you talking about the brake/coast jumpers on the victors? You can set the jumpers on the speed controllers to short the motors with a neutral command (127), this causes them to brake. You can also set them to coast on neutral, which lets the motors free spin. The jumper block is right below the PWM cable port on the victor.