Hi,
Short answer:
At the moment these constant do not have a big effect. Only the ratio between Ct and Cm is important.
Longer answer:
Ct is in Newton/command, it is the thrust at command 1 (max command).
Cm is in Newton.meter/command, it is the torque at command 1 (max command).
The formula is different from gazebo in that it does not use motor velocity but motor command which is between 0 and 1: F = motor_constant * motor_command
You can find the formulas used to compute the thrust here px_generate_mixers.py#L150-L157, and the one for the torque here: px_generate_mixers.py#L127-L134.
Also, the mixers are currently normalized px_generate_mixers.py#L191-L218 so
- the absolute values of Ct and Cm do not matter much
- the ratio between Ct and Cm is important if the rotors are not all horizontal
- if your platform have motors stronger than others, you can reflect it by setting larger Cts and Cms for the stronger motors
In the future I hope we can use non-normalized mixers so that Ct and Cm have more physical meaning.