One thing I do need to mention before I jump to that,

is we have an additional flow source that we need to supply.

And this happens to be that our, our tractive motor,

even with reasonable efficiency, has quite a large amount of leakage through it,

and the leakage is fairly comparable to what we would actually size that, the,

the engine pump for initially for these.

For just the, the road loads.

And so based on this we hae to oversize this pump to take care of the,

the leakage losses that would be going on in this motor.

So, I just wanted to raise that before we jump onto the simulation.

So here's what the simulation looks like.

I'm going to jump over to sim hydraulics and

we can look at this maybe a little bit more directly.

So, now what I've got going on here in sim hydraulics,

the main components I want you to be looking at.

Is over here on the left side, I've got the pump, and this would be,

really be the engine pump that is driving the system, and

this is my constant flow source, so the flow coming out of his,

this is going through a flow sensor, so this is just measuring the flow.

Fluoride coming out of the engine pump and then I have a flow meter,

again going to a hydraulic accumulator so this is my energy storage device.

And then I have this going over here to attract a motor.

This is what's driving the wheels of the vehicle, so

here is the, the wheel unit that's converting.

By rotational domain into linear domain.

Linear mechanical and

then attached to my linear mechanical I've got a mass right here.

This is the mass of the vehicle and

then I've the road loads which are both the aerodynamic drag and

the rolling resistance and then I'm going to measure that and.

Convert it into a velocity that I can plot right here with the velocity output.

So that's the system and I've gone ahead and plugged in these values so

if you look at the tractive motor, you can see that I happen to have

the the displacement of 3 times 10 to the minus 4th cubic meters per round which

is very close to what we had sized it at, during our, our sizing just a moment ago.

Did the same thing for

the accumulator, the same thing for this hydraulic flow source.

And this happens to be where I'm placing the volume flow rate for that, for

that flow source.

So I'm getting a little ahead of myself because I'm starting to talk about the two

different control strategies here.

And so the first control strategy is simply,

how do we track the velocity that we want to be creating in this drive cycle.

So what I'm going to do is I'm going to take the velocity that my vehicle actually

has that I'm measuring here and I'm going to compare it with my drive cycles.

In this upper left here I've got two different drive cycles,

I can either switch from my sign wave or I can switch to an imput,

this happens to be the urba, urban dynamometer driving schedule.

I'll go back to my, my sign wave.

And so, this will be my input and in this summing block,

I'll compare that with what the actual velocity is.

I then just have a proportional controller, so I am applying some gain to

this and then that is going into the command signal of the tractive motor.

So that is the displacement control of this tractive motor.

So that's how I am controlling the motor or the speed of the vehicle.

Now, as far as the engine pump remember I'm using the,

the pressure in the system and so I take this pressure source right here and

my accumulator pressure is now being fed back to over here and I'm using this

relay to say when the pressure drops below a certain threshold turn on this flow

source when it gets above a certain threshold turn it back off.

And I'm cycling on and off.

And you can play around with this in, in your own simulation.

So let me first of all run this through the sign wave and

we can look at how this behaves.