Driving: Tank, Arcade or FPS?

[JamesCH95]

As a (relatively) old-school driver I liked single-stick arcade control for FRC robots. This typically works best with a real gimbal'd joystick, where the driver can 'feel' center on the stick. Most common joysticks are not gimbal and thus lose a lot of the 'on-center' feeling that makes this control scheme beloved by many.

In recent years we've used game pads with single-stick arcade that I found easy to drive, and I liked it a lot. This takes some modest drive transforms to fine-tune to the driver's taste, but nothing complex. These transforms help address the 'on center' feeling and let the robot drive forward even if the thumb-stick is off-centered slightly.

I've got an RC car with 'dual stick' arcade that I like to drive and find very easy to control. The divorced axes for f/r and l/r are really nice and lets one send precisely the inputs they want.

I have raced a lot of Forza (car simulation game) which uses one thumb-stick for turning and two triggers for throttle/brake (forward/reverse on a robot) and like that too. The f/r and l/r axes are divorced, which is nice, and the forward/reverse axes are also divorced. For the extra-fine control required for a semi-realistic car sim it is great to be able to apply both the throttle and the brake, and I imagine it would work well for an FRC robot as well, but perhaps only marginally better than 'dual stick' arcade.

I absolutely cannot stand 'tank drive' where two joysticks are used. It forces the driver to do the drive 'math' in their head, something a computer is MUCH better suited to do. I never felt that it was intuitive, fluid, or an efficient use of controllers. I know some people/teams have been successful with it, but I can only imagine how much more successful they could have been with any of the controls described above.

[MrForbes]

The FPS configuration is the same as a traditional RC car controller, but instead of a trigger for the throttle and a steering wheel, it uses the right joystick Y axis for throttle, and left joystick X axis for steering.

Which makes it even stranger that we never figured this out, because we used an RC car controller to drive our robot in 2008 and 09.

[z_beeblebrox]

Originally Posted by MrForbes

The FPS configuration is the same as a traditional RC car controller, but instead of a trigger for the throttle and a steering wheel, it uses the right joystick Y axis for throttle, and left joystick X axis for steering.

Which makes it even stranger that we never figured this out, because we used an RC car controller to drive our robot in 2008 and 09.

When we don't have a holonomic drive, we still prefer the RC car controllers to FPS drive on a gamepad. We find the larger range of motion of the axes allows for more precise control of the robot than the tiny thumbsticks on a gamepad.

[RunawayEngineer]

My personal favorite way to drive a tank drivetrain is to use 2 single axis joysticks for tank drive control scheme. The removal of the degrees of freedom of the joysticks allows you way better feedback and control. This is because if you are off straight on a double-axis joystick, your hands will feel a different travel distance than the controls are being sent.

[Abhishek R]

Originally Posted by JamesCH95

I absolutely cannot stand 'tank drive' where two joysticks are used. It forces the driver to do the drive 'math' in their head, something a computer is MUCH better suited to do. I never felt that it was intuitive, fluid, or an efficient use of controllers. I know some people/teams have been successful with it, but I can only imagine how much more successful they could have been with any of the controls described above.

Agreed, it just doesn't seem natural, since the two sides are often driving in contradicting directions (I.e when you want to turn).

[JamesCH95]

Originally Posted by RunawayEngineer

My personal favorite way to drive a tank drivetrain is to use 2 single axis joysticks for tank drive control scheme. The removal of the degrees of freedom of the joysticks allows you way better feedback and control. This is because if you are off straight on a double-axis joystick, your hands will feel a different travel distance than the controls are being sent.

While that may be in improvement over two 2-axis joysticks, it still doesn't deal with the difference in dexterity between the driver's two hands. They will almost always have better dexterity with one hand than the other, and a single joystick will allow them to put that dexterity to use, instead of being dragged down by their less-dominant hand's performance.

Two-stick tank drive is like drawing with an etch-a-sketch and single-stick arcade is like drawing with a pencil; yeah, the etch-a-sketch can sometimes make a good approximation of a pencil drawing, but it's never going to be quite as good.

[JABot67]

RC Car Drive:
Left thumb Y axis gets mapped to ArcadeDrive forward-backward
Right thumb X axis gets mapped to ArcadeDrive turning



This drive control scheme is the only scheme that has been used by any of the teams I have been on, from 2007 to 2015. It gives the driver an absolutely guaranteed way of driving straight forward and back, and no other drive scheme mentioned here comes close. It also allows the driver to turn on a dime, with no forward-to-backward movement if none is required - useful when you don't have that much room.

One thing my team noticed in 2012 was that teams who used two-stick tank or one-stick arcade drive were struggling to balance the bridge. Thinking about it, it makes sense - when you are trying to drive slowly forward or backward with one of those drives, you may end up inadvertently turning.

This thread really should be a poll - I think RC car drive is actually a very popular drive (and is also by far my favorite! )

With mecanum and slide and swerve drive, different drive schemes have to be used. I would probably recommend the First-Person Shooter drive, using the free axis of the forward-backward stick to strafe.

[FTC5110]

In FTC and VEX land we run split arcade but for holonomic drives, to keep the driving controls mostly the same regardless of drive system, we add a fairly large deadband on the LH joystick X value so Y being forward/backward is "preferred" and left/right movement is available when required plus RH joystick X value for rotate allows for some fun driving.
This scheme in action: http://www.youtube.com/watch?v=ClGWg43TtCI

Might be handy since it's looking like FRC will have many holonomic drives this season.

[RunawayEngineer]

Originally Posted by JamesCH95

While that may be in improvement over two 2-axis joysticks, it still doesn't deal with the difference in dexterity between the driver's two hands. They will almost always have better dexterity with one hand than the other, and a single joystick will allow them to put that dexterity to use, instead of being dragged down by their less-dominant hand's performance.

Two-stick tank drive is like drawing with an etch-a-sketch and single-stick arcade is like drawing with a pencil; yeah, the etch-a-sketch can sometimes make a good approximation of a pencil drawing, but it's never going to be quite as good.

The dominant hand effect might be there, but I don't think that it is significant. First of all, I never noticed it in my years on a drive team.
But less anecdotally . . . look at guitar-playing: the non-dominant hand is doing at least equal dexterity tasks, probably moreso. Practice and muscle memory can remove that weakness from that activity.

[JamesCH95]

Originally Posted by JABot67

RC Car Drive:
Left thumb Y axis gets mapped to ArcadeDrive forward-backward
Right thumb X axis gets mapped to ArcadeDrive turning

[IMG]http://juguetedivertido.com/wp-content/uploads/2011/02/YY-4582Remote.jpg[IMG]

This drive control scheme is the only scheme that has been used by any of the teams I have been on, from 2007 to 2015. It gives the driver an absolutely guaranteed way of driving straight forward and back, and no other drive scheme mentioned here comes close. It also allows the driver to turn on a dime, with no forward-to-backward movement if none is required - useful when you don't have that much room.

One thing my team noticed in 2012 was that teams who used two-stick tank or one-stick arcade drive were struggling to balance the bridge. Thinking about it, it makes sense - when you are trying to drive slowly forward or backward with one of those drives, you may end up inadvertently turning.

This thread really should be a poll - I think RC car drive is actually a very popular drive (and is also by far my favorite! )

With mecanum and slide and swerve drive, different drive schemes have to be used. I would probably recommend the First-Person Shooter drive, using the free axis of the forward-backward stick to strafe.

It doesn't seem like you read the thread... what you call "RC car drive" is what is commonly know as "FPS" control. Other control methods, including single-stick arcade (with a gimbal stick), provide a reliable way to 'drive straight forward.'

Frankly, even FPS style control won't be guaranteed to drive perfectly straight without closed-loop control due to variances in motor torque and drivetrain drag. And when closed-loop control is in the mix, almost anything can manage to reliably drive straight.

It is a horrific and sweeping generalization to say that: "teams who used two-stick tank or one-stick arcade drive were struggling to balance the bridge." Your conclusion that their control system was holding them back is simply false.

Now, I'm not saying "FPS" drive is bad, it certainly is a great drive control scheme, but don't undercut your own argument by making such rash statements.

Originally Posted by RunawayEngineer

The dominant hand effect might be there, but I don't think that it is significant. First of all, I never noticed it in my years on a drive team.
But less anecdotally . . . look at guitar-playing: the non-dominant hand is doing at least equal dexterity tasks, probably moreso. Practice and muscle memory can remove that weakness from that activity.

Sure, lots of practice always helps. Perhaps that is not the best anti-two-stick-tank argument.

Still, how can a two-stick system drive straight at part-throttle? This is VERY difficult to do.

Consider this thread from last year: http://www.chiefdelphi.com/forums/sh...d.php?t=125759

Team 33 found that all drivers wound up preferring FPS-style control to two-stick tank and found it "way easier" to control their robot(s).

[blazeflipper]

This is an interesting system. I will suggest it to our programmer this afternoon and possibly start driving it around tonight! We normally use two stick tank drive. Something we will still do is to actually have two joysticks rather than just a gamepad. We found that when our drivers use a gamepad, they think of the robot as a warthog from Halo and just use full power all the time rather than slow careful movements when it's needed.

[MrForbes]

Originally Posted by blazeflipper

This is an interesting system. I will suggest it to our programmer this afternoon and possibly start driving it around tonight!

Thanks...for letting me know that it was worth my time to start this thread. This is the result I wanted--other teams discovering the same thing we discovered.

Who knows...it might even end up as part of the WPI library.

[JABot67]

Originally Posted by JamesCH95

It doesn't seem like you read the thread... what you call "RC car drive" is what is commonly know as "FPS" control. Other control methods, including single-stick arcade (with a gimbal stick), provide a reliable way to 'drive straight forward.'

Frankly, even FPS style control won't be guaranteed to drive perfectly straight without closed-loop control due to variances in motor torque and drivetrain drag. And when closed-loop control is in the mix, almost anything can manage to reliably drive straight.

It is a horrific and sweeping generalization to say that: "teams who used two-stick tank or one-stick arcade drive were struggling to balance the bridge." Your conclusion that their control system was holding them back is simply false.

Now, I'm not saying "FPS" drive is bad, it certainly is a great drive control scheme, but don't undercut your own argument by making such rash statements.

This drive is called "First-Person Shooter Drive" by the first poster in this thread, then called "Split Arcade Drive", "Kaj Drive", and "RC Car Drive" during this thread. I don't think it has a universal name, but you are right that I should not have presented the name I use as the correct name.

Regarding "FPS Drive", I think the name is actually good for describing a drive that allows strafing - many FPSes (Halo, etc.) allow you to strafe using the left joystick (same one for going forward and backward).

"RC Car Drive" could also be considered a bad name for the control scheme, because real RC cars are not tank drive and can't turn on a dime.

Regarding the rest of your post, I am glad we agree that it is very important to have a foolproof way of going straight forward and backward. I am very curious about everyone's opinion about what drive control schemes perform the best, or if it matters at all. I think that your chosen scheme does impact your performance, but not as much as driver skill and practice.

And yes, one of my statements up there could be considered a "horrific and sweeping generalization". I was considering removing it, but I'll leave it there for now. This was my first controversial post on CD!!

[DarkRune]

Running octocanum this year, and because of the driver (I don't know why, he just likes it and it seems to work well) the traction wheels will be controlled via tank, however the mecanum drive will be a sort of split arcade where one joystick is f/b/l/r and one joystick is purely turning. Kind of a weird setup, but he likes it and it seems to work.

[artdutra04]

I used to prefer 2-joystick tank drive to regular arcade, but after trying split-arcade, it's my new favorite. Very intuitive, especially for anyone who has played video games.

IMHO the terms "split-arcade" and "FPS" control modes are not interchangeable terms for the same thing.

Split-arcade is for skid-steer robots, as it cannot handle strafing of any kind. FPS can only be used on swerve/mecanum/holonomic robots where the left joystick is full X-Y translation and the right joystick is rotation.