Insert the torque sensor and the Ideal rotational motion sensor in a Simscape Model

I am working on a Simscape multibody model of a 4 wheeled vehicle. Due to the presence of encoders, I need to identify the value of the angular speed of the motors. At the same time, I need to detect the value of the torque, because the multibody revolute joint requires the torque as an input value. For these reasons, I need both the Torque sensor and the Ideal Rotational Motion sensor. So here's the problem: when I connect together the two sensors, as seen in figure, one of them has a value of 0 (as seen in the scope). If I remove one of the two sensors, the value detected is correct. How can I fix this? The connection may be the problem? If so, how should the two sensors be connected?

All the other parameters (Voltage value, DC Motor parameters, etc) of the model are fine.

[VBBV]

Hi @Joseph Thomas Chun,

can you check what happens when you connect the C port of rotation speed sensor directly to the C-port attached to DC-motor, just as you did for torque sensor ?

[Joseph Thomas Chun]

It's the same. It's always zero.

Answer 1

[Chaitanya]

Hello Joseph

I see that you are trying to measure torque and angular speed using torque sensor and ideal rotational motion sensor in your simscape model.

From the diagram, I see that the orientation of the sensors are incorrect.

Torque is a through variable (similar to current). This means you need to connect the torque sensor in series with the block you want to measure.

Angular velocity is an across variable (similar to voltage). This means you need to connect it in parallel with the block you want to measure to get the relative velocity across its two ports.

Please refer to the following documentation for better understanding of through variables and across variables in simscape.

https://www.mathworks.com/help/simscape/ug/basic-principles-of-modeling-physical-networks.html#bq89sba-3

Please rectify the connections and verify if you are able to see both the reading.

I hope the above information helps

Thanks,

Chaitanya