RE:Slide Joints and physics optimization

[nige777]

Hi,

I have constructed a virtual environment containing, amongst other things, a forklift. As the "name of the game" for this project was realism I have constructed the truck using purely physics joints. This works well, the truck follows the lay of the land and behaves pretty well how i want it to. However, one of the tasks for the user is to load some items (steel cages) onto the back of a lorry, at this point things go a bit weird. I am using a slide joint for the forks and 'applyForce' on joystick button events (within a timer) to raise and lower them, but when I pick up the cages they bounce and jump all over the place - not good. I have tried everything i can think of -reducing the physics stepsize (0.0003) and accuracy (0.000001), altering the weight, bounce and friction of the forks and cages, all of which have an effect, but not really what I want.
Is applyForce the best way to operate this type of slide joint, or is having it within a timer making the forks movement jumpy???? HELP, i've run out of ideas and this has to be finished by beginning of next week!!

This is the code for the cages:

top =cage1.collideBox(node = 'Cage_Top',bounce=0,density=.1)
top.setFriction(80)
bottom = cage1.collideBox(node = 'Cage_Bottom',bounce=0,density=.4)
bottom.setFriction(80)
side1=cage1.collideBox(node='Left_Ones',bounce=0,density=0.05)
side2=cage1.collideBox(node='Right_Ones',bounce=0,density=0.05)
cage1.enable(viz.COLLIDE_NOTIFY)

This is the code for the FLT:

#Build FLT#
###########
flt = viz.add('flt8.ive')
body = flt.getChild('Body')
body.playsound('CE2a.WAV',viz.LOOP)
body.collideBox(bounce=0, density = 1.25)

lever1=flt.getChild('Lever1')
lever1.collideBox(bounce=0,density=0.05)
lever2=flt.getChild('Lever02')
lever2.collideBox(bounce=0,density=0.05)

#Get and process children
run = flt.getChild('Shaft')
run.collideBox(bounce=0, density = 0.1)
run.setPosition([0.0,0.2,0.0])
print run.getPosition()

guard = flt.getChild('ForkGuard')
guard.translate([0,0,0.005])
guard.collideBox(bounce=0,density=0.05)

fork1 = flt.getChild('Blades')
#fork1.setPosition(0,-0.1,0)
forks = fork1.collideBox(bounce=0,density = 0.1)
forks.setFriction(200)

steering = flt.getChild('Steering_Wheel')
steerBox = steering.collideSphere(bounce=0,density=0.01)

#Link
bodyLink = viz.link(body,view,dstFlag=viz.LINK_BODY)
bodyLink.preTrans([0,-0.12,0.28])

##--MOTORS & JOINTS--##

steerlink = viz.phys.addHingeJoint(body,steering,pos=[-0.005,1.153,0.813],axis0=[0,1,0])
steerlink.setMotorAngle(0,0,1,.25)

#lever1link = viz.phys.addHingeJoint(body,lever1,pos=[0.249,0.763,0.993],axis0=[1,0,0])
lever1link=viz.phys.addFixedJoint(body,lever1)
lever2link=viz.phys.addFixedJoint(body,lever2)
#lever1link.setMotorAngle(0,0,100,.5)

slideJoint = viz.phys.addSliderJoint(fork1,run,pos=[-0.005,0.5,1.317],axis0=(0,1,0))
slideJoint.setAxisFriction(0,12)
slideJoint.setAxisLimit(0,-0.2,2.8) # Limit sliding distance

guardJoint = viz.phys.addFixedJoint(guard,fork1)
#cwLink = viz.phys.addFixedJoint(cw,body)
#runJoint = viz.phys.addFixedJoint(run,body)
runJoint = viz.phys.addHingeJoint(run,body,pos=[-0.005,0.279,1.21],axis0=[1,0,0]) 
#runJoint.setAxisFriction(0,10)
#runJoint.setAxisLimit(0,-5,8)
runJoint.setMotorAngle(0,-1,26,1)
 
fr = viz.add('F_wheel1.ive',scale = [1,1,1],pos=[0.58,0.194,0.9])
fright = fr.collideSphere(bounce = 0, density = 1)
fright.setFriction(5)
frJoint = viz.phys.addHingeJoint(body,fr,pos=[0.58,0.194,0.9],axis0=(-1,0,0))
frJoint.setAxisFriction(0,1.5)

fl = viz.add('F_wheel1.ive',scale = [1,1,1],pos=[-0.58,0.194,0.9])
fleft = fl.collideSphere(bounce = 0, density =1)
fleft.setFriction(5)
flJoint = viz.phys.addHingeJoint(body,fl,pos=[-0.58,0.194,0.9],axis0=(-1,0,0))
flJoint.setAxisFriction(0,1.5)

rr = viz.add('F_wheel1.ive',scale=[1,1,1],pos=[0.0,0.194,-0.727])
#rr.playsound('CE2a.WAV',viz.LOOP)
rearr = rr.collideSphere(bounce = 0, density = 3)
rearr.setFriction(2)
rrJoint = viz.phys.addWheelJoint(body,rr,pos=[0.0,0.194,-0.727],axis0=(0,1,0),axis1=(1,0,0))
rrJoint.setAxisBounce(0,0)
rrJoint.setAxisBounce(1,0)
rrJoint.setAxisFriction(1,.75)
print rrJoint.getPosition()


def steer(val):
    rrJoint.setMotorAngle(0,val,0xFF,.05)
    
def steerWheel(val):
    steerlink.setMotorAngle(0,val,3,.1) 
    
def SetThrottle(val):
    rrJoint.setMotorThrottle(1,-val,9,1100)

#Control Forks#
def buttonTimer():

    
    if joy.isButtonDown (7):
        print "Button is 7 down"
        fork1.applyForce([0,215,0])
        
    elif joy.isButtonDown (8):
        print "Button 8 is down"
        fork1.applyForce ([0,-205,0])
        
    if joy.isButtonDown (5):
        runJoint.setMotorAngle(0,-6,6,.03)
    elif joy.isButtonDown (6):
        runJoint.setMotorAngle(0,2,6,.03)

        
vizact.ontimer(viz.FASTEST_EXPIRATION,buttonTimer)

Any help, suggestions, information will be VERY gratefully received.

Cheers,

Nige