Backlash block does not simulate gears backlash

Different behavior is shown by the simscape backlash block, which is designed to more accurately model the backlash of gears. See picture below. Note: it is speeds, not angles. What I am referring to is initial constantness of speed when it changes direction. Also ignore staircase-like behavior: obviously, it is more accurate model then simulink's one so it takes more physical processes into account.

You can compare it to the output of simulink backlash block (for convenience, see below from official example, note: this is angles). Here one can see initial angle constantness.

I think, simulink's block does not simulate gears backlash correctly (and simscape block does). Gears disengage when torque changes sign => when speed changes direction (because at this moment motor will start pushing in the opposite direction then before, but there is no contact to the opposite gear => backlash occures. Exactly at this moment torque = 0 (changes its sign) and speed tries to change direction: before this moment gear was accelerating and after it starts to slow down). So this constantness should occure on the speed level. But disangagment should be calculated on the angles level. Therefore it can't be simulated by simulink's block (and indeed simulink's simscape block shows different behaviour).

P.S. Sorry for my english, it is not my native language.

Editted: fix: it is simscape driveline block, not multibody.

[Pat Gipper]

The Simulink backlash block is simply a hysteresis element without any involvement between two masses. If you insert a Simulink dead zone block between the difference of the positions of two masses you should be able to get similar results. Generally, the output of the dean zone needs to be converted into a force that is applied in opposite directions to the two masses.

[Alexander Novak]

Thank you for your answer! I think your solution is great and will help me, but I do not think that in such case backlash block should be called backlash.

I understand that simscape block simulates a lot more processes (it not only takes into account masses but also collisions of gears with damping etc.), but that is not what I am having problem with.

And I mostly agree that simulink's backlash block is more like a hysteresis (the only difference is that it is disengaged at the start while hysteresis is not).

What I am having problem with is that it does not realy simulate backlash: it should disengage when the speed (the first derivative of the input) changes direction (or torque (second derivative) changes sign) and engage the output depending on the angle difference (input itself). And when disengaged remain speed constant. But at the moment it does all operations on the input.

I may be wrong, but I think I am not because simulink simscape's block backlash simulates backlash differently then simulink's one (and I am not talking about more accurate model which results in steps in the output) (and I think it simulates it as described above).

It is stated that simulink backlash block can be used ot model backlash as is (see below), but I do not think so. (simscape's one does not have such detailed descriptino unfortunately).