Problems about mass of target objects and quadrotor with suction gripper

[xirhxq]

Hello sir,

We have two questions about mass of target objects and quadrotor with suction gripper.

1. Among the small objects, we notice only one of them named small_case is 3kg weight, while others are all 1kg. We wonder if there is a mistake here.

2. Even if we modified the mass to 1kg, we still cannot lift this object successfully by quadrotor with suction gripper. Eventually, we find the maximum thrust produced by the motor is $4\times2.52\times 10^{-5}\times800^2=64.5\text N$ by using motor_constant and maxRotVelocity in the file mbzirc_ign/models/mbzirc_quadrotor/model.sdf.erb. However, the weight of quadrotor with suction gripper & target object is greater than $\rm 1.5(quadrotor)+2(end \space effector)+2(suction)+1(object)=6.5kg$, which means it is an impossible task. Are there any solutions? or does it simply mean that we can't use quadrotor & suction gripper for this task?

Best regards.

[iche033]

Hi, thanks for catching this. We have updated the Small Case model. You can clear your model cache to force the simulator to download the updated version:

rm -fr ~/.ignition/fuel/fuel.ignitionrobotics.org/openrobotics/models/small\ case/

Even if we modified the mass to 1kg, we still cannot lift this object successfully by quadrotor with suction gripper.

We gave it a test and saw that it should now work though: