Velocity feedback from vehicle body is coming out to be negative

I am trying to simulate a vehicle model using vehicle body block. I created the vehicle subsystem using some SIMULINK by connecting motor rotational output to tires(magic formula) and tires to vehicle body and the subsystem to motor, H-bridge and giving drive cycle to get the velocity output. But when I try to simulate model my velocity is going in negative Y axis. I tried changing the solver parameters but didn’t work. I've tried starting from scratch and rechecked my connections so many times but nothing. I've no idea why this keeps happening. I've even tried it on both online and downloaded versions.

Please Help!

[Sam Chak]

Hi @Chetanvir Singh

Can you re-describe the problem in math and diagram?

It makes investigating your problem much easier.

[Chetanvir Singh]

Hi @Sam Chak,

The blue graph is for refence velocity given by the specified drive cycle and the yellow graph is for velocity feedback from the vehicle body.

Due to this the distance travelled also comes out to be negative.

[Sam Chak]

Hi @Chetanvir Singh

Thanks for showing the graph and the diagram. If the distance travelled should be in the positive direction, could it be the polarity issue?

[Chetanvir Singh]

Hi @Sam Chak

Thanks for replying. I've checked all the connections and polarity for the same, but there's no change in the results.

[Sam Chak]

I see. Then you probably have to go back to the fundamentals: the governing math of the system or algorithm of the control block. Almost everything can be explained once you identify culprit behind the math.

[Chetanvir Singh]

Hi @Sam Chak

Thank you so much for your time and help. I'll check the algorithm and block specifications and then try!

Answer 1

[Steve Miller]

Without looking at the model directly it is hard to be sure. Given the top speed is reached pretty quickly, I suspect your powertrain is turning the wheels in the wrong direction. The error increases, the powertrain drives the car as fast as it can until drag prevents it from accelerating any faster.

Solution: check the setting on your gear block. Setting "Output shaft rotates" is probably set to "In opposite direction to input shaft". Set it to "In same direction as input shaft".

--Steve