enable pdControlPlugin by default (requires pdControlPlugin.cpp and b3RobotSimulatorClientAPI_NoDirect.cpp)

add pdControl.py example, make pdControlPlugin functional
reduce memory usage
fix examples/pybullet/gym/pybullet_data/random_urdfs/948/948.urdf, fixes issue #1704

examples/pybullet/examples/pdControl.py

@@ -0,0 +1,62 @@
+
+import pybullet as p
+import time
+
+useMaximalCoordinates=False
+p.connect(p.GUI)
+pole = p.loadURDF("cartpole.urdf", useMaximalCoordinates=useMaximalCoordinates)
+for i in range (p.getNumJoints(pole)):
+	#disable default constraint-based motors
+	p.setJointMotorControl2(pole,i,p.POSITION_CONTROL,targetPosition=0,force=0)
+	print("joint",i,"=",p.getJointInfo(pole,i))
+
+
+desiredPosCartId = p.addUserDebugParameter("desiredPosCart",-10,10,2)
+desiredVelCartId = p.addUserDebugParameter("desiredVelCart",-10,10,0)
+kpCartId = p.addUserDebugParameter("kpCart",0,500,300)
+kdCartId = p.addUserDebugParameter("kpCart",0,300,150)
+maxForceCartId = p.addUserDebugParameter("maxForceCart",0,5000,1000)
+
+
+desiredPosPoleId = p.addUserDebugParameter("desiredPosPole",-10,10,0)
+desiredVelPoleId = p.addUserDebugParameter("desiredVelPole",-10,10,0)
+kpPoleId = p.addUserDebugParameter("kpPole",0,500,200)
+kdPoleId = p.addUserDebugParameter("kpPole",0,300,100)
+maxForcePoleId = p.addUserDebugParameter("maxForcePole",0,5000,1000)
+
+pd = p.loadPlugin("pdControlPlugin")
+
+	
+p.setGravity(0,0,0)
+
+useRealTimeSim = True
+
+p.setRealTimeSimulation(useRealTimeSim)
+	
+p.setTimeStep(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.executePluginCommand(pd,"test",[1, pole, link], [desiredPosCart, desiredVelCart, kdCart, kpCart, maxForceCart])
+		
+		desiredPosPole = p.readUserDebugParameter(desiredPosPoleId)
+		desiredVelPole = p.readUserDebugParameter(desiredVelPoleId)
+		kpPole = p.readUserDebugParameter(kpPoleId)
+		kdPole = p.readUserDebugParameter(kdPoleId)
+		maxForcePole = p.readUserDebugParameter(maxForcePoleId)
+		link = 1
+		p.executePluginCommand(pd,"test",[1, pole, link], [desiredPosPole, desiredVelPole, kdPole, kpPole, maxForcePole])
+		
+
+	if (not useRealTimeSim):
+		p.stepSimulation()
+		time.sleep(1./240.)
+	
+