Why don't I ever see robots that steer like a car

[team1203 4life]

Originally Posted by Capt. Quirk

Wouldn't that be an advantage in this competition?

because the turning radius is to large and would put you out of position

p.s sorry if this was already posted didnt read through all of them

[Jherbie53]

Like the others have said, it would be hard for you to turn around and go backwards in a quadrant. Other than that, this years game would promote it I think. If you decided not to hurdle the trackball or pick the trackball up off the ground, then you could build a really nice drive train that turns easy and could push the trackball around the track. I don't how easy it would be to build a CAR like drive train,( I'm not that technically inclined in this area ).

The reason why I think most teams don't use it is, like Kevin Sevcik said, you have to do a Y turn to turn around and its so much easier to have a drive train that can spin in a tight radius. Another reason is that it might be harder to build a CAR steering mechanism rather than lining up 6 wheels and running chain to all the wheels from a gearbox.

[1086wulf]

Car like steering was not really advantageous in the past because the games were more of maneuverability. This year however, since you will be running around the track, I would think if your strategy is to just run around to get points then it would work well. If you are herding it may cause some problems if you lose control and try to get the ball back.

[Kit Gerhart]

Originally Posted by Capt. Quirk

Wouldn't that be an advantage in this competition?

This year, for the first time since I've been involved with FIRST (12 years) we discussed car type steering briefly. For this game it might have an advantage in that you would have better precision when driving through holes in traffic than with tank type drives. The down side, as others have mentioned, is that you can't "turn in place" as with tank drive. Because of it's simplicity, I'm sure most teams will use tank drive this year, but will be practicing some different driving skills than for most previous FIRST games.

[R3P0]

Team 1504 is making this kind of steering.

Isn't overdrive NASCAR for robots with a huge ball?


R3P0

[petek]

My typical overthink analysis of this question:
Ignoring other aspects of the game, if you want to go just for the absolute minimum lap time, I suspect that an automotive-style drive train and ackerman steering system would be the ticket. In either rear-wheel drive or four-wheel drive form, in principle there should be less frictional losses and smoother direction change control.

One gotcha with this is your un-steered wheels need to compensate for the different driven path length around corners. A differential can lead to sitting still with one driven wheel spinning while drifting (sliding) a solid axle takes more finesse to drive and re-introduces frictional losses, so I'd opt for differential control of the motors driving the wheels (sync'ing them to the steering angle).

In the real world of Overdrive I think all this is moot, because it will be pretty darn hard to get a clear lap to make use of the little bit of extra speed you might have. Besides, us oldtimers recall a certain Evil Machine with six-wheel drive and tank steering that just plain flew around the field a few years back, proving that drive system can be fast, manuverable and push like an irresitable force - without any complicated steering system.

[deshirider430]

612 (05') http://www.chantillyrobotics.com/pho...?g2_itemId=875

[JesseK]

What I'd like to see is a tractor-style turning mechanism. 3 CIMs on 1 transmission that drives 2 rear wheels from a differential. To turn, all you do is brake the side you want to turn to. Put unpowered omnis on the front and BAM there you go -- seems easy enough right?

[Capt. Quirk]

Originally Posted by petek

One gotcha with this is your un-steered wheels need to compensate for the different driven path length around corners. A differential can lead to sitting still with one driven wheel spinning while drifting (sliding) a solid axle takes more finesse to drive and re-introduces frictional losses, so I'd opt for differential control of the motors driving the wheels (sync'ing them to the steering angle).

The easy way around that is to just let your inside wheels freewheel through the corners. The differential and "Steering Brakes" like JesseK suggested would turn wickedly fast. Programming for the turn angle or using a Go-Kart style chassis that lifts 1 wheel and with programming, could drive 3 wheels would be another option.


Nice pictures deshirider430, how did it work?. I was worried that using the window motors would limit how quickly the bot could change directions?

Originally Posted by JesseK

What I'd like to see is a tractor-style turning mechanism. 3 CIMs on 1 transmission that drives 2 rear wheels from a differential. To turn, all you do is brake the side you want to turn to. Put unpowered omnis on the front and BAM there you go -- seems easy enough right?

A differential wouldn't be hard to make and I think multiple motors feeding a differential would be a great idea, Especially for the 6 wheel drive "tractor style" drive train. All it would take is steering brakes and then the outside bank would receive full power.

[dlavery]

Originally Posted by petek

My typical overthink analysis of this question:
Ignoring other aspects of the game, if you want to go just for the absolute minimum lap time, I suspect that an automotive-style drive train and ackerman steering system would be the ticket. In either rear-wheel drive or four-wheel drive form, in principle there should be less frictional losses and smoother direction change control.

After going through a similar overthink analysis, we came up with a different approach that should beat an automotive-style drive train with Ackerman steering - and arguably almost any other "standard" system. I won't just give it away, but let's just say that it involves reducing the deceleration time required to make the turn at the end of the Lane Divider to the absolute minimum amount of time possible, and constructing the ability to withstand repeated 53-G impacts into the robot.

-dave



.

[Cory]

Originally Posted by dlavery

After going through a similar overthink analysis, we came up with a different approach that should beat an automotive-style drive train with Ackerman steering - and arguably almost any other "standard" system. I won't just give it away, but let's just say that it involves reducing the deceleration time required to make the turn at the end of the Lane Divider to the absolute minimum amount of time possible, and constructing the ability to withstand repeated 53-G impacts into the robot.

-dave



.

So you decided to go with this, afterall?

[dlavery]

Originally Posted by Cory

So you decided to go with this, afterall?

We will see after the CDR on Saturday. Either way, it is a fun idea (if we don't go with it, it may still be a fun off-season project to prepare for IRI).

-dave

[Travis Hoffman]

Originally Posted by Kit Gerhart

Because of it's simplicity, I'm sure most teams will use tank drive this year, but will be practicing some different driving skills than for most previous FIRST games.

Actually, those who were adept at patrolling the area around the rack by driving in arcs last season may discover that that skill directly translates into making smooth gradual turns through the lane dividers with a tank steering setup this season.

[Travis Hoffman]

Originally Posted by dlavery

After going through a similar overthink analysis, we came up with a different approach that should beat an automotive-style drive train with Ackerman steering - and arguably almost any other "standard" system. I won't just give it away, but let's just say that it involves reducing the deceleration time required to make the turn at the end of the Lane Divider to the absolute minimum amount of time possible, and constructing the ability to withstand repeated 53-G impacts into the robot.

-dave



.

Bat-Steer? Holy CO2 grapnels, Batman!

[Capt. Quirk]

Originally Posted by dlavery

and constructing the ability to withstand repeated 53-G impacts into the robot.

-dave.

By the ball, wall or other robots?