Real-Time Physics Simulation Forum 2022-05-20T18:11:10+00:00 https://pybullet.org/Bullet/phpBB3/app.php/feed/topic/13439 2022-05-20T18:11:10+00:00 2022-05-20T18:11:10+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=44022#p44022 <![CDATA[Issues using Inverse Kinematics on Spherical Joints (DeepMimic Humanoid)]]> I am working on trying to apply Inverse Kinematics to DeepMimic's humanoid model (https://github.com/xbpeng/DeepMimic/blo ... noid3d.txt) in order to slightly alter the character's motion in real time.

In order to figure out how to do so I have reduced the problem into a small example - Trying to modify the Humanoid's left wrist position using Inverse Kinematics.
The humanoid has 8 Spherical Joints and 4 Revolute Joints

I wrote the following code in order to try to dynamically alter the humanoid's wrist position taking in new values from the user:

Code: 

endEffector = 14curPos = self._get_joint_pose(phys_model, endEffector)[0]if(self.first):self.first = False self.c = [self._pybullet_client.addUserDebugParameter("lWrist x", -2, 2, curPos[0]), self._pybullet_client.addUserDebugParameter("lWrist y", -2, 2, curPos[1]), self._pybullet_client.addUserDebugParameter("lWrist z", -2, 2, curPos[2])]targetPos = [self._pybullet_client.readUserDebugParameter(self.c[0]), self._pybullet_client.readUserDebugParameter(self.c[1]), self._pybullet_client.readUserDebugParameter(self.c[2])]jointPoses = self._pybullet_client.calculateInverseKinematics(phys_model, endEffector, targetPos)currentPointer = 0for i in range(s.num_joints):jtype = s.joint_types[i]if jtype is JointType.BASE: #Rootpass      elif jtype is JointType.FIXED: #R/L Wrist        pass      elif jtype is JointType.REVOLUTE: #R/L Knee ; R/L Elbow        self._pybullet_client.resetJointStateMultiDof(phys_model, i, [jointPoses[currentPointer]])       currentPointer += 1      elif jtype is JointType.SPHERE: #Chest ; Neck ; R/L Hip ; R/L Ankle ; R/L Shoulder        quat = self._pybullet_client.getQuaternionFromEuler([jointPoses[currentPointer], jointPoses[currentPointer+1], jointPoses[currentPointer+2]])        self._pybullet_client.resetJointStateMultiDof(phys_model, i, quat)        currentPointer += 3
However, I am not getting the expected results as the final outcome appears distorted/incorrect.

Image
Image

I believe the issue has to do with me not really knowing what to do with the outcome of the CalculateInverseKinematics function. I have tried looking at other examples, but I couldn't find anyone else using a combination of InverseKinematics and Spherical Joints. Has anyone tried doing something similar (i.e using InverseKinematics on Spherical joints/the DeepMimic Humanoid.urdf)?

Statistics: Posted by Herou — Fri May 20, 2022 6:11 pm

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