The problem of simulating absolute grip

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In summary, Brian Beckman found that there is an equation that can be used to calculate the correct amount of sideways force to apply to each wheel in order to simulate absolute grip. However, he cautioned that it is not an exact science and that most people fall victim to the Newtonian friction problems.
  • #1
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Ok, so I'm not even bothering with tire friction simulation anymore. What I'm trying to simulate is a tire that has 100% grip at all times (no lateral velocity.) Now you see that the statement I just made has a contradiction in it...If a car has 4 tires, and if a car is rotating, it is impossible for all 4 tires to have zero lateral velocity (unless all 4 tires have ackerman steering.)
However, using ackerman steering would simply be a cop-out way for never really having to solve the underlying problems.
So basically, I am going to list the problems with simulating absolute grip here (For now we are completely ignoring friction equations and just trying to have tires that try their best to grip 100%.)
upload_2017-4-10_10-57-0.png

to explain problem 1 more in depth, the problem is phy_speed updates only after the physics has been applied, so that the entity must first move forward before it can change the lateral velocity of the tires.

To explain more of problem 2 more, the overall goal is to cancel all lateral velocity of the tire...This results in pure longitudal velocity for each tire...BUT if this is the goal...then look at the paralelogram location of the tires...the actual destination of the tires cannot be this, because each tire follows a curve with a radius, the path of the inside tire cannot be same length as the outside tire...thus simply putting the tires where the pure longitudal velocity indicates, cannot possibly be the right method.

I am really at a loss. Any Brian Beckman's in the audience?
 
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  • #2
Wheel speed difference . Inside pair v outside pair .
 
  • #3
quickquestion said:
I am really at a loss. Any Brian Beckman's in the audience?
Have you actually tried doing a web search on car physics simulation? There seems to be plenty out there, including example code etc.
 
  • #4
Nidum said:
Wheel speed difference . Inside pair v outside pair .
Yes, but we are dealing with Box 2D physics, it has no such thing as wheels. All we have to work with is abstract thrust vectors. So in terms of Box 2D, we are looking to cancel the sideways speed of the wheels, and I'm not sure how knowing the inside longitudal speed will give us the needed sideways force. Basically I will say exactly what I am after: Basically I am trying to find an equation that will tell me the correct amount of sideways force to apply to each wheel. So that right there basically sums up what I'm after.

A.T. said:
Have you actually tried doing a web search on car physics simulation? There seems to be plenty out there, including example code etc.
Have done tons of searching, none really suited my fancy. Some examples were better than others, Iforce 2D was pretty bad and basic, others were more advanced but still not quite right or realistic. I stumbled upon Brian Beckman's car physics and he said it was basically not an exact science, and he was the first guy to discover the "combined grip/slip" equation. He said he wasn't sure his math was right (this document was 10 years ago.) The reason for this is I suspect most fall prey to the Newtonian physics friction problems...Newtonian models give an incorrect analysis of friction, In real life a car-wheel (longitudally), behaves like a cog on a toothed rail. But laterally, it behaves like a damping field. Newtonian model attempts to crudely represent behaviors as a thrust force (which, unfortunately, thrust forces are the pretty much the only available functions available to my physics engine.)

That being said, what particular car physics examples do you recommend for me?
 

Related to The problem of simulating absolute grip

1. What is "The problem of simulating absolute grip"?

The problem of simulating absolute grip refers to the challenge of creating a simulation or model that accurately represents the sensation of grip or the sense of touch. It involves understanding the complex interactions between the brain, nerves, and muscles that allow us to sense and control grip in the real world.

2. Why is simulating absolute grip important?

Simulating absolute grip is important for various fields such as robotics, virtual reality, and medical research. The ability to accurately simulate grip can enhance the realism and functionality of prosthetics, improve training and rehabilitation programs, and advance our understanding of the human body and brain.

3. What are the challenges in simulating absolute grip?

There are several challenges in simulating absolute grip, including the complexity of the human nervous system, the variety of factors that contribute to the sensation of grip, and the lack of a complete understanding of how grip is processed and controlled by the brain.

4. How have scientists approached the problem of simulating absolute grip?

Scientists have used various approaches to tackle the problem of simulating absolute grip, including studying the physiology of the hand and fingers, developing advanced sensors and actuators, and utilizing computer simulations and artificial intelligence algorithms.

5. What are some potential applications of simulating absolute grip?

The ability to simulate absolute grip has potential applications in fields such as prosthetics, human-computer interaction, gaming, and sports training. It can also aid in the development of innovative technologies and therapies for individuals with sensory or motor impairments.

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