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baxter_ik_demo.py
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baxter_ik_demo.py
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from time import sleep
import pybullet as p
import numpy as np
def setUpWorld(initialSimSteps=100):
"""
Reset the simulation to the beginning and reload all models.
Parameters
----------
initialSimSteps : int
Returns
-------
baxterId : int
endEffectorId : int
"""
p.resetSimulation()
# Load plane
p.loadURDF("plane.urdf", [0, 0, -1], useFixedBase=True)
sleep(0.1)
p.configureDebugVisualizer(p.COV_ENABLE_RENDERING,0)
# Load Baxter
baxterId = p.loadURDF("baxter_common/baxter_description/urdf/toms_baxter.urdf", useFixedBase=True)
p.resetBasePositionAndOrientation(baxterId, [0.5, -0.8, 0.0], [0., 0., -1., -1.])
#p.resetBasePositionAndOrientation(baxterId, [0.5, -0.8, 0.0],[0,0,0,1])
#p.resetBasePositionAndOrientation(baxterId, [0, 0, 0], )
p.configureDebugVisualizer(p.COV_ENABLE_RENDERING,1)
# Grab relevant joint IDs
endEffectorId = 48 # (left gripper left finger)
# Set gravity
p.setGravity(0., 0., -10.)
# Let the world run for a bit
for _ in range(initialSimSteps):
p.stepSimulation()
return baxterId, endEffectorId
def getJointRanges(bodyId, includeFixed=False):
"""
Parameters
----------
bodyId : int
includeFixed : bool
Returns
-------
lowerLimits : [ float ] * numDofs
upperLimits : [ float ] * numDofs
jointRanges : [ float ] * numDofs
restPoses : [ float ] * numDofs
"""
lowerLimits, upperLimits, jointRanges, restPoses = [], [], [], []
numJoints = p.getNumJoints(bodyId)
for i in range(numJoints):
jointInfo = p.getJointInfo(bodyId, i)
if includeFixed or jointInfo[3] > -1:
ll, ul = jointInfo[8:10]
jr = ul - ll
# For simplicity, assume resting state == initial state
rp = p.getJointState(bodyId, i)[0]
lowerLimits.append(-2)
upperLimits.append(2)
jointRanges.append(2)
restPoses.append(rp)
return lowerLimits, upperLimits, jointRanges, restPoses
def accurateIK(bodyId, endEffectorId, targetPosition, lowerLimits, upperLimits, jointRanges, restPoses,
useNullSpace=False, maxIter=10, threshold=1e-4):
"""
Parameters
----------
bodyId : int
endEffectorId : int
targetPosition : [float, float, float]
lowerLimits : [float]
upperLimits : [float]
jointRanges : [float]
restPoses : [float]
useNullSpace : bool
maxIter : int
threshold : float
Returns
-------
jointPoses : [float] * numDofs
"""
closeEnough = False
iter = 0
dist2 = 1e30
numJoints = p.getNumJoints(baxterId)
while (not closeEnough and iter<maxIter):
if useNullSpace:
jointPoses = p.calculateInverseKinematics(bodyId, endEffectorId, targetPosition,
lowerLimits=lowerLimits, upperLimits=upperLimits, jointRanges=jointRanges,
restPoses=restPoses)
else:
jointPoses = p.calculateInverseKinematics(bodyId, endEffectorId, targetPosition)
for i in range(numJoints):
jointInfo = p.getJointInfo(bodyId, i)
qIndex = jointInfo[3]
if qIndex > -1:
p.resetJointState(bodyId,i,jointPoses[qIndex-7])
ls = p.getLinkState(bodyId,endEffectorId)
newPos = ls[4]
diff = [targetPosition[0]-newPos[0],targetPosition[1]-newPos[1],targetPosition[2]-newPos[2]]
dist2 = np.sqrt((diff[0]*diff[0] + diff[1]*diff[1] + diff[2]*diff[2]))
print("dist2=",dist2)
closeEnough = (dist2 < threshold)
iter=iter+1
print("iter=",iter)
return jointPoses
def setMotors(bodyId, jointPoses):
"""
Parameters
----------
bodyId : int
jointPoses : [float] * numDofs
"""
numJoints = p.getNumJoints(bodyId)
for i in range(numJoints):
jointInfo = p.getJointInfo(bodyId, i)
#print(jointInfo)
qIndex = jointInfo[3]
if qIndex > -1:
p.setJointMotorControl2(bodyIndex=bodyId, jointIndex=i, controlMode=p.POSITION_CONTROL,
targetPosition=jointPoses[qIndex-7])
if __name__ == "__main__":
guiClient = p.connect(p.GUI)
p.resetDebugVisualizerCamera(2., 180, 0., [0.52, 0.2, np.pi/4.])
targetPosXId = p.addUserDebugParameter("targetPosX",-1,1,0.2)
targetPosYId = p.addUserDebugParameter("targetPosY",-1,1,0)
targetPosZId = p.addUserDebugParameter("targetPosZ",-1,1,-0.1)
nullSpaceId = p.addUserDebugParameter("nullSpace",0,1,1)
baxterId, endEffectorId = setUpWorld()
lowerLimits, upperLimits, jointRanges, restPoses = getJointRanges(baxterId, includeFixed=False)
#targetPosition = [0.2, 0.8, -0.1]
#targetPosition = [0.8, 0.2, -0.1]
targetPosition = [0.2, 0.0, -0.1]
p.addUserDebugText("TARGET", targetPosition, textColorRGB=[1,0,0], textSize=1.5)
maxIters = 100000
sleep(1.)
p.getCameraImage(320,200, renderer=p.ER_BULLET_HARDWARE_OPENGL )
for _ in range(maxIters):
p.stepSimulation()
targetPosX = p.readUserDebugParameter(targetPosXId)
targetPosY = p.readUserDebugParameter(targetPosYId)
targetPosZ = p.readUserDebugParameter(targetPosZId)
nullSpace = p.readUserDebugParameter(nullSpaceId)
targetPosition=[targetPosX,targetPosY,targetPosZ]
useNullSpace = nullSpace>0.5
print("useNullSpace=",useNullSpace)
jointPoses = accurateIK(baxterId, endEffectorId, targetPosition, lowerLimits, upperLimits, jointRanges, restPoses, useNullSpace=useNullSpace)
setMotors(baxterId, jointPoses)
#sleep(0.1)