add example comparing explicit PD control (Python), explicit PD control (plugin), position constraint and stable PD control (Python)

This commit is contained in:
erwincoumans 2018-12-19 20:12:19 -08:00
parent 69321a9ee6
commit 78de1f070f
2 changed files with 131 additions and 25 deletions

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@ -1,26 +1,49 @@
import pybullet as p
from pdControllerExplicit import PDControllerExplicit
from pdControllerExplicit import PDControllerStable
import time
useMaximalCoordinates=False
p.connect(p.GUI)
pole = p.loadURDF("cartpole.urdf", useMaximalCoordinates=useMaximalCoordinates)
for i in range (p.getNumJoints(pole)):
pole = p.loadURDF("cartpole.urdf", [0,0,0], useMaximalCoordinates=useMaximalCoordinates)
pole2 = p.loadURDF("cartpole.urdf", [0,1,0], useMaximalCoordinates=useMaximalCoordinates)
pole3 = p.loadURDF("cartpole.urdf", [0,2,0], useMaximalCoordinates=useMaximalCoordinates)
pole4 = p.loadURDF("cartpole.urdf", [0,3,0], useMaximalCoordinates=useMaximalCoordinates)
exPD = PDControllerExplicit(p)
sPD = PDControllerStable(p)
for i in range (p.getNumJoints(pole2)):
#disable default constraint-based motors
p.setJointMotorControl2(pole,i,p.POSITION_CONTROL,targetPosition=0,force=0)
print("joint",i,"=",p.getJointInfo(pole,i))
p.setJointMotorControl2(pole2,i,p.POSITION_CONTROL,targetPosition=0,force=0)
p.setJointMotorControl2(pole3,i,p.POSITION_CONTROL,targetPosition=0,force=0)
p.setJointMotorControl2(pole4,i,p.POSITION_CONTROL,targetPosition=0,force=0)
#print("joint",i,"=",p.getJointInfo(pole2,i))
timeStepId = p.addUserDebugParameter("timeStep",0.001,0.1,0.01)
desiredPosCartId = p.addUserDebugParameter("desiredPosCart",-10,10,2)
desiredVelCartId = p.addUserDebugParameter("desiredVelCart",-10,10,0)
kpCartId = p.addUserDebugParameter("kpCart",0,500,300)
kpCartId = p.addUserDebugParameter("kpCart",0,500,1300)
kdCartId = p.addUserDebugParameter("kdCart",0,300,150)
maxForceCartId = p.addUserDebugParameter("maxForceCart",0,5000,1000)
textColor = [1,1,1]
shift = 0.05
p.addUserDebugText("explicit PD", [shift,0,.1],textColor,parentObjectUniqueId=pole,parentLinkIndex=1)
p.addUserDebugText("explicit PD plugin", [shift,0,-.1],textColor,parentObjectUniqueId=pole2,parentLinkIndex=1)
p.addUserDebugText("stablePD", [shift,0,.1],textColor,parentObjectUniqueId=pole4,parentLinkIndex=1)
p.addUserDebugText("position constraint", [shift,0,-.1],textColor,parentObjectUniqueId=pole3,parentLinkIndex=1)
desiredPosPoleId = p.addUserDebugParameter("desiredPosPole",-10,10,0)
desiredVelPoleId = p.addUserDebugParameter("desiredVelPole",-10,10,0)
kpPoleId = p.addUserDebugParameter("kpPole",0,500,200)
kpPoleId = p.addUserDebugParameter("kpPole",0,500,1200)
kdPoleId = p.addUserDebugParameter("kdPole",0,300,100)
maxForcePoleId = p.addUserDebugParameter("maxForcePole",0,5000,1000)
@ -29,34 +52,50 @@ pd = p.loadPlugin("pdControlPlugin")
p.setGravity(0,0,-10)
useRealTimeSim = True
useRealTimeSim = False
p.setRealTimeSimulation(useRealTimeSim)
p.setTimeStep(0.001)
timeStep = 0.001
while p.isConnected():
if (pd>=0):
desiredPosCart = p.readUserDebugParameter(desiredPosCartId)
desiredVelCart = p.readUserDebugParameter(desiredVelCartId)
kpCart = p.readUserDebugParameter(kpCartId)
kdCart = p.readUserDebugParameter(kdCartId)
maxForceCart = p.readUserDebugParameter(maxForceCartId)
link = 0
p.setJointMotorControl2(bodyUniqueId=pole,jointIndex=link,controlMode=p.PD_CONTROL,targetPosition=desiredPosCart,targetVelocity=desiredVelCart,force=maxForceCart, positionGain=kpCart, velocityGain=kdCart)
desiredPosPole = p.readUserDebugParameter(desiredPosPoleId)
desiredVelPole = p.readUserDebugParameter(desiredVelPoleId)
kpPole = p.readUserDebugParameter(kpPoleId)
kdPole = p.readUserDebugParameter(kdPoleId)
maxForcePole = p.readUserDebugParameter(maxForcePoleId)
link = 1
p.setJointMotorControl2(bodyUniqueId=pole,jointIndex=link,controlMode=p.PD_CONTROL,targetPosition=desiredPosPole,targetVelocity=desiredVelPole,force=maxForcePole, positionGain=kpPole, velocityGain=kdPole)
p.getCameraImage(320,200)
timeStep = p.readUserDebugParameter(timeStepId)
p.setTimeStep(timeStep)
desiredPosCart = p.readUserDebugParameter(desiredPosCartId)
desiredVelCart = p.readUserDebugParameter(desiredVelCartId)
kpCart = p.readUserDebugParameter(kpCartId)
kdCart = p.readUserDebugParameter(kdCartId)
maxForceCart = p.readUserDebugParameter(maxForceCartId)
desiredPosPole = p.readUserDebugParameter(desiredPosPoleId)
desiredVelPole = p.readUserDebugParameter(desiredVelPoleId)
kpPole = p.readUserDebugParameter(kpPoleId)
kdPole = p.readUserDebugParameter(kdPoleId)
maxForcePole = p.readUserDebugParameter(maxForcePoleId)
taus = exPD.computePD(pole, [0,1], [desiredPosCart,desiredPosPole],[desiredVelCart,desiredVelPole], [kpCart,kpPole], [kdCart,kdPole],[maxForceCart,maxForcePole], timeStep)
p.setJointMotorControlArray(pole, [0,1], controlMode=p.TORQUE_CONTROL, forces=taus)
if (pd>=0):
link = 0
p.setJointMotorControl2(bodyUniqueId=pole2,jointIndex=link,controlMode=p.PD_CONTROL,targetPosition=desiredPosCart,targetVelocity=desiredVelCart,force=maxForceCart, positionGain=kpCart, velocityGain=kdCart)
link = 1
p.setJointMotorControl2(bodyUniqueId=pole2,jointIndex=link,controlMode=p.PD_CONTROL,targetPosition=desiredPosPole,targetVelocity=desiredVelPole,force=maxForcePole, positionGain=kpPole, velocityGain=kdPole)
taus = sPD.computePD(pole4, [0,1], [desiredPosCart,desiredPosPole],[desiredVelCart,desiredVelPole], [kpCart,kpPole], [kdCart,kdPole],[maxForceCart,maxForcePole], timeStep)
p.setJointMotorControlArray(pole4, [0,1], controlMode=p.TORQUE_CONTROL, forces=taus)
p.setJointMotorControl2(pole3,0, p.POSITION_CONTROL, targetPosition=desiredPosCart, targetVelocity=desiredVelCart, positionGain=timeStep*(kpCart/150.), velocityGain=0.5, force=maxForceCart)
p.setJointMotorControl2(pole3,1, p.POSITION_CONTROL, targetPosition=desiredPosPole, targetVelocity=desiredVelPole, positionGain=timeStep*(kpPole/150.), velocityGain=0.5, force=maxForcePole)
if (not useRealTimeSim):
p.stepSimulation()
time.sleep(1./240.)
time.sleep(timeStep)

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@ -0,0 +1,67 @@
import numpy as np
class PDControllerExplicit(object):
def __init__(self, pb):
self._pb = pb
def computePD(self, bodyUniqueId, jointIndices, desiredPositions, desiredVelocities, kps, kds, maxForces, timeStep):
numJoints = self._pb.getNumJoints(bodyUniqueId)
jointStates = self._pb.getJointStates(bodyUniqueId, jointIndices)
q1 = []
qdot1 = []
for i in range (numJoints):
q1.append(jointStates[i][0])
qdot1.append(jointStates[i][1])
q = np.array(q1)
qdot=np.array(qdot1)
qdes = np.array(desiredPositions)
qdotdes = np.array(desiredVelocities)
qError = qdes - q
qdotError = qdotdes - qdot
Kp = np.diagflat(kps)
Kd = np.diagflat(kds)
forces = Kp.dot(qError) + Kd.dot(qdotError)
maxF = np.array(maxForces)
forces = np.clip(forces, -maxF , maxF )
return forces
class PDControllerStable(object):
def __init__(self, pb):
self._pb = pb
def computePD(self, bodyUniqueId, jointIndices, desiredPositions, desiredVelocities, kps, kds, maxForces, timeStep):
numJoints = self._pb.getNumJoints(bodyUniqueId)
jointStates = self._pb.getJointStates(bodyUniqueId, jointIndices)
q1 = []
qdot1 = []
zeroAccelerations = []
for i in range (numJoints):
q1.append(jointStates[i][0])
qdot1.append(jointStates[i][1])
zeroAccelerations.append(0)
q = np.array(q1)
qdot=np.array(qdot1)
qdes = np.array(desiredPositions)
qdotdes = np.array(desiredVelocities)
qError = qdes - q
qdotError = qdotdes - qdot
Kp = np.diagflat(kps)
Kd = np.diagflat(kds)
p = Kp.dot(qError)
d = Kd.dot(qdotError)
forces = p + d
M1 = self._pb.calculateMassMatrix(bodyUniqueId,q1)
M2 = np.array(M1)
M = (M2 + Kd * timeStep)
c1 = self._pb.calculateInverseDynamics(bodyUniqueId, q1, qdot1, zeroAccelerations)
c = np.array(c1)
A = M
b = -c + p + d
qddot = np.linalg.solve(A, b)
tau = p + d - Kd.dot(qddot) * timeStep
maxF = np.array(maxForces)
forces = np.clip(tau, -maxF , maxF )
#print("c=",c)
return tau