Applying torque control in PyByllet makes object fly away from the secene - bulletphysics

Question

So I grabbed latest code from https://github.com/bulletphysics/pybullet_robots
I modified laikago.py example to the following, I'm only controlling one joint using torque.
Strangely enough poor robot flies away from the scene :)
There are two ways to fix it: either decrease simulation time step (line 10) or change torque value to 60 (line 33).
Any ideas what am I doing wrong?
import pybullet as p
import time
import os
os.chdir(os.path.dirname(os.path.abspath(__file__)))
p.connect(p.GUI)
plane = p.loadURDF("data/plane.urdf")
p.setGravity(0,0,-9.8)
timeStep = 1./300 # HERE!!! changing it to 1./400 fixes the problem
p.setTimeStep(timeStep)
urdfFlags = p.URDF_USE_SELF_COLLISION
quadruped = p.loadURDF("laikago/laikago_toes.urdf",[0,0,.5],[0,0.5,0.5,0], flags = urdfFlags,useFixedBase=False)
#enable collision between lower legs (2,5,8 and 11)
lower_legs = [2,5,8,11]
for l0 in lower_legs:
for l1 in lower_legs:
if (l1>l0):
p.setCollisionFilterPair(quadruped, quadruped, l0, l1, 1)
#set damping
for j in range (p.getNumJoints(quadruped)):
p.changeDynamics(quadruped, j, linearDamping=0, angularDamping=100)
p.setJointMotorControl2(quadruped, j, p.VELOCITY_CONTROL, force=0)
#run the simulation
p.setRealTimeSimulation(0)
for i in range (1000):
p.setJointMotorControl2(quadruped, 13, p.TORQUE_CONTROL, force=62) # HERE!!! changing it to force=60 fixes the problem
p.stepSimulation()
time.sleep(timeStep)

Answer 1

I am a bit late to the party, but maybe you are still in search of an answer. The reason is given here: https://pybullet.org/Bullet/phpBB3/viewtopic.php?t=12644 and a note was added to: https://docs.google.com/document/d/10sXEhzFRSnvFcl3XxNGhnD4N2SedqwdAvK3dsihxVUA/edit#heading=h.jxof6bt5vhut
The reason: "You need to first unlock/disable the default velocity/position motor. [...] Otherwise, your force/torque has to exceed the default motor." (see first link).
To fix do (same link):
pybullet.setJointMotorControl2(objUid, linkIndex, p.VELOCITY_CONTROL, force=0)