Overworked jaguars
 

Our jaguar on our conveyor belt will run and then stop after a few seconds. There is a minor mechanical problem, but there is friction acting upon the motor. This is a CIM motor on a torque setup with one other sprocket with the conveyor belt attached. I ran into this problem when they were ready to test the shoot (a two wheel apparatus on a CIM motor) and the wires would get hot and sparks were arcing from the battery due to friction. This was because of a speed gear setup. When they fixed it, it was on a jaguar. When the motor hit full speed, the jaguar was overworked and the jaguar had a slow blinking light for about 2 to 3 seconds and it would go back to normal. I determined, on accident and with a mentor realizing the issue, that when you slowly work the motor up for a few seconds and hit full speed, then the motor will run for a long time. With the conveyor belt, I feel that there is too much friction because it would either run or twitch the chain at random points in time with the overworked red light. Any suggestions will be very helpful!

Thanks in advanced and Happy Competitions!::safety::

Re: Overworked jaguars
 

Add slew rate limiting to your motor commands.

http://www.chiefdelphi.com/forums/sh...23&postcount=2

Re: Overworked jaguars
 

While you can ramp the motor up in code as well, Jaguars also allow you to configure the hardware so that it always ramps, regardless.

See Q4 and Q5 here to understand what automatic ramp mode is.

The guide for implementing automatic ramp mode is here on p11-12.

Re: Overworked jaguars
 

Some thoughts:

1) The user-configurable ramp feaure in the Jag is available only if CAN bus is being used to command the Jag.

2) I think they may want to ramp in one direction only. Does the ramp feature in the Jags allow for that?

3) What is the slowest ramp rate supported by the Jag ramp feature? Sounds like they are going to need something on the order of seconds, not fractions of a second. Is that supported?

Re: Overworked jaguars
 

Well, let's see what you think with this info:

I am programming in Java and I had the program on an axis control for testing. I recently programmed a speed buttons and will test it tomorrow. This is a SimpleRobot setup and we are not using CAN setups.

The direction is only one direction and I do not seem to understand how to answer the last two quests/thoughts, possibly due to terminology.

I have seen your single post of the rate-limit and have had programmers block on implementing that system with a single button use.

I hope I supplied enough information. If not, catch me on it and tell me what you think!

Thanks again for the help!

Re: Overworked jaguars
 

I'm not entirely sure; our experience with Jaguars has been quite dismal, so we've never actually had to use this command. If their shooter is that difficult to turn though, wouldn't they want bidirectional ramping regardless?

According to the CAN guide (see p14), the user-configurable rate is a "16-bit 8.8 unsigned fixed point number", so I would suppose so (but cannot confirm).

Re: Overworked jaguars
 

I can figure out the intended meaning of the above sentence. Could you please try wording it a different way?

Re: Overworked jaguars
 

Well, the motor (conveyor) is being set to a if(button hit) then move motor this set speed (unknown until testing done). Basically a single button conveyor belt movement.

Any ideas?

Re: Overworked jaguars
 

The problem you describe implies that the gearing on your shooter necessitates some sort of ramping feature; that is, rather than an instantaneous change in supplied power, a gradual change. This is implemented by rate-limiting, which implements a maximum rate of change so that the Jaguar's over current protection will not cut in and stop your shooter.

My suggestion was to use the Jaguar's automatic ramp mode, which can be done by changing the jumper configuration on the limit switches from both vertical to both horizontal; this ramps the power change over a sixteenth of a second (assuming you're going from zero to full forward). Refer to p12 of the document I originally linked for a diagram of what the jumper configuration should look like.

Re: Overworked jaguars
 

Yes. Run that set speed through the rate limiter before passing it on to the motor. The output of the rate limiter will limit the rate of change of the motor command. You can make it as slow (or fast) as you like.

Re: Overworked jaguars
 

from the original post: