Re: Shooter Problem
 

Having played with a similar setup this is almost certainly the problem. Gaffer's tape on the arc worked really well, if you don't have any of that masking tape would probably work about as well. We're going to try hockey tape tomorrow.

Re: Shooter Problem
 

We have plans to try several of the tricks mentioned here, and we'll try to report back with our findings.

Re: Shooter Problem
 

Check and make sure the wheel is tighten to the axle and is not slipping

Re: Shooter Problem
 

We found tread material to give us the most difference in performance. We use wedgetop wheel tread and it works well on a 6 inch wheel.

Re: Shooter Problem
 

OK, let's say it is slipping 90% - you would never be able to see this with your 'bare eyes'.

As Ian Curtis mentioned, try some tape on the plexi. Then come back and tell me it didn't work, But not before you try it, all right?

Re: Shooter Problem
 

This is what we're planning to try tomorrow. And we'll set it up so we can play with the speeds, by using chain drive and computer speed control, eventually with a PID loop of some type.

Re: Shooter Problem
 

We are using a 8 inch high grip wheel directly driven with a cim

Re: Shooter Problem
 

Try P-only and crank the gain up to the sky*. If you've got enough inertia in the wheel, and you run the loop at 10ms, that's all the tuning you should need.


* this will mimic a bang-bang controller.

Re: Shooter Problem
 

We know how we're going to shoot but how we're going to put the frisbees in to the robot or how will the robot going to pick it up????.

Re: Shooter Problem
 

Yeah, I'd say that you might want to go with a bang-bang controller.

If you get flack from your mechanical/fabricators for "slamming" the motor, do what I did, add a linear cushion within ~3% of your target speed.
Ex. For a shooter wheel capable of 10,000RPM when you're over 300 RPM lower than your setpoint, you go 100% power, when you're 150 RPM Lower, 75%, Dead on 50%, 150RPM Higher 25%, 300RPM Higher 0%.

This will mimic the PID you're trying to use, and unless you really know what you're doing when PID tuning, will be half the headache.

Re: Shooter Problem
 

Seriously? Are you saying there was some visible or audible manifestation?

If so, check the following and fix if necessary:

- make sure the motor controller jumper is in the "coast" position (not "brake").

- make sure you are running the control loop fast enough (10 ms is good)

- make sure your sensor is capable of giving an up-to-date speed reading faster than your control loop iteration rate

Re: Shooter Problem
 

I didn't know what I know now when I made that control loop last year, and I just dropped it in autonomous and teleop. Obviously a case of it not running fast enough. Still, even our poor bang-bang controller was better than a PID for this application.