Hello, I am simulating a 7-DoF robotic arm, and wanna assign the position of one joint like following (before 'mj_step(m, d);', in the main loop): int id4 = mj_name2id(m, mjOBJ_JOINT, "robot_joint_4"); d->qpos[m->jnt_qposadr[id4]] = 0.5; However, I got the following error during simulation: WARNING: Nan, Inf or huge value in QACC at DOF 1. The simulation is unstable. Time = 3.3100. While the remaining joints work well. The simulated robot behaves as it has been reseted to its original position at this error time point. Could you please give me any hints about this problem? Thanks.