Using p.setJointMotorControlArray with joint_forces runs false

[hitzhukui]

when I ues p.setJointMotorControlArray in position_control, if set the joint_forces as the urdf gives, or try any other values, the (panda/kuka) robot runs chaos in simulation. When abandon joint_force and use defaults (maybe: [0,0,0,0,0]), it runs normally. So i want to know how the max_forces parameter works or how to solve my problem. Thanks