getJointState and StateLogging

[ZZHPKU]

I use setJointMotorControlMultiDof(ObjectId, JointId, controlMode=p.TORQUE_CONTROL, force=force) and p.stepSimulation() to do a simulation and I set numSubSteps=1. Also, I use p.getJointState(ObjectIDd, JointId) to obtain the force (torque) it applies which should be stored in appliedJointMotorTorque. However, I find that appliedJointMotorTorque is not equal to force I input.

I'd like to know what appliedJointMotorTorque means and why the difference occured. My code is as follows.

import pybullet as p import numpy as np from utilities import readLogFile

import time

useMaximalCoordinates = False import pybullet_data

p.connect(p.GUI) p.setAdditionalSearchPath(pybullet_data.getDataPath())

print(pybullet_data.getDataPath())

pole = p.loadURDF("cartpole.urdf", [0, 0, 0], useMaximalCoordinates=useMaximalCoordinates)

p.setGravity(0, 0, -9.8)

timeStep = 0.01

taus = [10., 10.]

logID = p.startStateLogging(p.STATE_LOGGING_GENERIC_ROBOT, r"mytest\test.txt",logFlags = p.STATE_LOG_JOINT_TORQUES) p.setPhysicsEngineParameter(fixedTimeStep=timeStep, numSubSteps=1) torque_use = [] for i in range(5): for j in [0, 1]: p.setJointMotorControlMultiDof(pole, j, controlMode=p.TORQUE_CONTROL, force=[taus[j]])

p.stepSimulation()
[jointPosition,jointVelocity,jointReactionForces,appliedJointMotorTorque0] = p.getJointState(pole,0)
[jointPosition,jointVelocity,jointReactionForces,appliedJointMotorTorque1] = p.getJointState(pole,1)
torque_use.append([appliedJointMotorTorque0, appliedJointMotorTorque1])

p.stopStateLogging(logID)

a = np.array(readLogFile(r"mytest\test.txt", True)) a = a[:,41:43] print(a) print(np.array(torque_use)) print('stop')

What's more, I use startStateLogging to log torque. I think it should be equal to appliedJointMotorTorque but it doesn't in fact. What happened?