Programming Autonomous pneumatic kicker

[billbo911]

Originally Posted by tanguma26

Can you explain me more about what you said about a single state machine i dont understand

or if you have any more advise i would apresiated.


thank you

Let's start with what a State Machine is. It is a series of steps, or states, that a machine or software runs through to perform a task.

Let's use the kicker as an example.

State 1: Precharge Kicker
State 2: Wait for "Fire" signal. Release kicker.
State 3: Wait .5 sec. for kick to complete.
State 4: Retract kicking mechanism.
State 5: Wait for retraction to complete.
State 6: Latch mechanism. Return to state 1.

The best advice I can give at this point is to visit http://www.lvmastery.com/tipjar

It will teach you all you need to know to start building state machines.
(This is not a paid advertisement for LVMastery.com)

I'm attaching an example vi. You will also need to create the DevRefNum's in the begin.vi.

[archwaykitten]

I am trying to make a very similar state machine kicker myself.

My problem is this: Say you tell your program to "wait" in a particular state for two seconds while a piston extends... I would expect the rest of your program to "freeze" for two seconds while that state machine code waits to execute. We want to be able to continue driving around and entering comands while our ball kicker state machine does its thing.

[billbo911]

Originally Posted by archwaykitten

I am trying to make a very similar state machine kicker myself.

My problem is this: Say you tell your program to "wait" in a particular state for two seconds while a piston extends... I would expect the rest of your program to "freeze" for two seconds while that state machine code waits to execute. We want to be able to continue driving around and entering comands while our ball kicker state machine does its thing.

The key is to have the vi run parallel to all other process. This way the other process, ie teleop.vi, do not have to wait for the kicker to cycle. We did this by placing the kicker state mchine in the main.vi. (See the attached picture) It requires no input from any other processes to complete, therefore it runs immediately. It also doesn't output any information that other vis need.

[I am error]

Hi,
I tried you example, changed everything around and put it in the main vi, but it did not function properly and i could not drive my motors in teleop. I'm trying to make so that when a button a latch is released by a piston retracting to fire a kicker from the default, then two pistons extend to reach the kicker and the latch piston extends to grab the kicker. Then the two pistons retract to rearm the device and the cycle repeats. I tried to implement that to your example but with no luck and also while running I could not drive the motors on the robot. Thanks for any help.

[Greg McKaskle]

You can of course do what you want with your code, but the framework gave you places to put code so that you wouldn't need to modify Robot Main.

Any code that you put into TeleOp or the Robot Main loop needs to finish within 20ms or it will start to affect the joystick code handling. This can be done provided you write the code to retain when something started and do time comparisons to determine when to move to the next kicker stage, note that time, etc.

OR

You can write the code with delays, but put that code into a parallel loop such as Periodic. Then in teleOp, you read the joystick and other stuff and if the conditions are right, you trigger a kick by setting a global. In periodic, you poll the global and start the sequence. At the end of the sequence, you clear the global.

Greg McKaskle

[Ether]

Originally Posted by archwaykitten

I am trying to make a very similar state machine kicker myself.

My problem is this: Say you tell your program to "wait" in a particular state for two seconds while a piston extends... I would expect the rest of your program to "freeze" for two seconds while that state machine code waits to execute. We want to be able to continue driving around and entering comands while our ball kicker state machine does its thing.

The "wait" in a state machine is NOT code that causes the processor to loop there until a desired amount of time has passed. Rather, it is code that tests whether the desired amount of time has passed, and if not, allows execution to continue. On the next iteration, it tests again. It keeps testing every new iteration until the desired time has elapsed, at which point it performs some action and changes state so it is no longer waiting.

You can put such a state machine in teleop along with other state machines and they will all peacefully coexist - i.e. they will all appear to execute "simultaneously", since none of them contain any code that "freezes" the processor waiting for time to elapse.

~