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I. Steering Models.
===================
1. Full
(car_physsteering*.x3d)
5 moving parts plus wheels and body.
Ackerman steering implemented using physics.
  x------x------x
 O-\           /-O
    x---------x
    |         |
    |         |
    |         |
    |         |
 O--x---------x--O
Doesn't work well at this point.

2. Simple
(car_mathsteering*.x3d)
No extra moving parts, just wheels.
Ackerman steering implemented using math.
Wheels are turned to the correct angles given by the physical model,
	but the joints are not present.
Methods of turning the wheels:
	i. Torque
	Works pretty well, but oscillation results.
	ii. Velocity
	Apply velocity instead of torque to greatly reduce oscillation.

3. Direct - Abandoned!
Try to remove oscillation seen in simple steering model.
Directly set the rotation of the wheels instead of applying forces.
Doubtful utility.


===================
II. Braking Models.
===================
1. Add to Acceleration
(car*_velbrakes.x3d)
A braking factor is added to the torque applied to the wheels by the accelerator.
Results in oscillation.
If setting velocity to accelerate, the oscillation is greatly reduced.

2. Hammer Brakes
(car*_hammerbrakes.x3d)
A block is forced down on top of the wheel
Works ok, but block slides down the front or back of the wheel if torque is applied to the wheel joint.
i. Modify CFM to fix oscillation
Maybe the cfm could be adjusted?
Yes, reducing global cfm to 0.001 fixed the sliding.
But at high speeds weird stuff happens with both the front wheels and the brakes.
High speeds mess with the brakes, low cfm somehow messes with the front wheels.
ii. Use Hinge2JointD and servomotor-like mechanics
This still has some issues.  HingeJointD would be better as it removes exactly 5 DOF all at once,
	but HingeJointD has no angle output field.
Maybe CFM could still be adjusted to keep the blocks on top of the wheels.

3. Bike Brakes - Abandoned!
Thin boxes are forced against the sides of cylindrical wheels.
Because of cylinder collision mechanics, this doesn't work.

4. Velocity Brakes - Abandoned!
Braking tries to directly set the velocity of the back wheel joints.
This doesn't work at all - probably.  I didn't spend much time on it.


=========================
III. Acceleration Models.
=========================
It might be worth comparing these, or just doing something like part IV and choosing one.
1. Set Wheel Torque

2. Set Wheel Velocity


=========================
IV. Acceleration Methods.
=========================
I've done no real study of the differences here, just some observations.
1. Back Wheel Drive - Abandoned?
Seemed like a good idea at the time.

2. Front Wheel Drive
Seems to hinder steering less than back wheel drive.

3. All Wheel Drive
???


===================
V. Braking Methods.
===================
1. Back Brakes

2. Front Brakes

3. Both Brakes

4. Adaptive Brakes
Brakes with wheels that would not cause flipping.