Upper Velocity Limit by a Joint control loop

[qiushi.ji]

Hi Marc,

I'm now trying writing program in joint callback script instead of child script because of the delay time every simulation time.
One question actually I've just forgot asking before weeks ago:
If a joint can reach a speed of e.g. 3600°, why the max. number of "Upper velocity limit" is 1145.92 in Joint Dynamic Properties? It just jumps back to 1145.92 if I enter a bigger number.

One little question, I'm always confused myself about the word "simulation time" or "simulation step" which present dt and dt/10times in physic engine... how to say it correctly? is it simulation time = simulation step/10?

Cheers,
Ji

[coppelia]

Hello Ji,

the Upper velocity limit is used when the control loop is enabled, when the position control mode or spring-damper mode is enabled. In that case it doesn't make sense to allow for higher velocities.

When you write your own controller via a joint callback script, then you are free to ignore that upper limit. Your callback script is handed that upper limit in the first line, last value:

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init,revolute,cyclic,jointHandle,passCnt,totalPasses,currentPos,targetPos,errorValue,effort,dynStepSize,lowLimit,highLimit,targetVel,maxForceTorque,velUpperLimit=...

You can use the variable velUpperLimit, or you can ignore it and simply return the velocity that you wish to apply:

Code: Select all

-- Following data must be returned to V-REP:
return forceOrTorqueToApply,velocityToApply

Then you have:

• simulation time: is not constant and represents the simulation progression. By default, it varies like: 0, 50ms, 100ms, 150ms, 200ms, etc.
• simulation step: is by default what happens during 50ms of simulation. In each simulation step the main script is called exactly once.
• simulation time step: is by default 50 ms. You can change it here.
• dynamic time step: is by default 5ms. By default a simulatioj step is composed by 10 dynamic simulation steps. You can change the dynamic time step here.

Cheers

[xxm]

Hi,coppelia

When the control loop is enabled, when the position control mode or spring-damper mode is enabled,do you have any way to improve upper velocity limit? when velocity is 1000deg/s,my robot is 1m/s,but I want my robot run faster,for example 5m/s,10m/s.I do not know what should I do .

Look forward to your replay!