Torque calculations for a small electric vehicle

[domnu_filip]

I believe that we already have covered that.
Please, see:

https://www.engineeringtoolbox.com/cars-power-torque-d_1784.html

https://www.engineeringtoolbox.com/tractive-effort-d_1783.html

https://www.engineeringtoolbox.com/car-acceleration-d_1309.html

If I have the wheels mounted directly on the BLDC motor axle, how should I calculate the wheel torque?
I ask this because, if I send the command to the motor, e.g. 5 Nm necessary to keep the vehicle steady on the incline, how do I get the feedback for the control loop?
So, if I calculated that the vehicle needs 5 Nm to rest on the slope, it is correct to measure the wheel torque and consider it as feedback to my torque control loop?
And how do I should I calculate the wheel torque in this case?

 

[jack action]

Wouldn't your feedback come from an accelerometer? You set a certain amount of torque, expecting a certain amount of acceleration. If the resulting acceleration is different from what is expected, you apply the necessary correction.

 

[domnu_filip]

Wouldn't your feedback come from an accelerometer? You set a certain amount of torque, expecting a certain amount of acceleration. If the resulting acceleration is different from what is expected, you apply the necessary correction.

Yes, but how do I convert it? And btw I want it to rest...

 

[jack action]

If you want the acceleration to be zero (at rest), then you have calculated a constant value for your torque $C$, say 5 N.m. If the vehicle accelerate (+ve or -ve), then you need to counterbalance your torque by the amount of acceleration $a$ that is measured (it should be zero).

So you get your new torque value $T$ to apply with $T = C + rma$ where $r$ is your wheel radius, $m$ is the vehicle mass and $a$ the measured acceleration.

If you can measure the velocity $v$, that is even better, because your trying to reach for $v = 0$, which is your true objective. then the desired acceleration might be to reach for $\frac{dv}{dt}$ where $dv$ will be some fraction of $v$ and $dt$ will be based on your feedback loop time interval.

 

[domnu_filip]

If you want the acceleration to be zero (at rest), then you have calculated a constant value for your torque $C$, say 5 N.m. If the vehicle accelerate (+ve or -ve), then you need to counterbalance your torque by the amount of acceleration $a$ that is measured (it should be zero).

So you get your new torque value $T$ to apply with $T = C + rma$ where $r$ is your wheel radius, $m$ is the vehicle mass and $a$ the measured acceleration.

If you can measure the velocity $v$, that is even better, because your trying to reach for $v = 0$, which is your true objective. then the desired acceleration might be to reach for $\frac{dv}{dt}$ where $dv$ will be some fraction of $v$ and $dt$ will be based on your feedback loop time interval.

I have the speed of the motor axle is spining, in rad/s, if I have the wheel directly on that axle, or a hub-motor (segway), can I use that value?

 

[jack action]

Yes

 

[domnu_filip]

Hello guys, I'm working for a home project and I want to made a simulation on a BLDC motor, which have a wheel attached to it's axle. (It is a part of small cart, 2 BLDC motors with 2 wheels directly mounted on the axle). So can I control the torque this way? What regulator should I use? How to integrate the load torque in motor subsystem?

 

[domnu_filip]

No one?..

 

[anorlunda]

What regulator should I use?

When I shop for BLDC motors online, I see that many of the include the manufacturer's regulator as part of the package.