Beyond velocity and acceleration: jerk, snap and higher derivatives (2016)

I wish designers of vehicles - particularly cars, trains and busses, would work to minimize jerk, snap and crackle.

Turns out if you minimize those, you get a far more comfortable ride. It matters far more than acceleration.

Finite element models of the whole system (tyres and suspension components and flexing elements of the vehicle body and road/track) can quickly allow analysis of the jerk, snap and crackle, and allow tuning of damping and drive system control loops to make a far more comfortable ride.

>I wish designers of vehicles - particularly cars, trains and busses, would work to minimize jerk, snap and crackle.

They do.

>Turns out if you minimize those, you get a far more comfortable ride. It matters far more than acceleration.

They know that this is the case. And put a lot of effort into making sure your car has the desired feel.

Besides your comfort these considerations are extremely important for the durability analysis for the vehicle.

>Finite element models of the whole system (tyres and suspension components and flexing elements of the vehicle body and road/track) can quickly allow analysis of the jerk, snap and crackle, and allow tuning of damping and drive system control loops to make a far more comfortable ride.

Finite element simulations are undesirable, they are extremely calculation expensive for those kind of large models and somewhat unsuitable. They are used in crash tests.

For the application you described multi body systems are used, where the car is decomposed into its functional components, which can be modeled either as stiff or flexible. With that you have a reasonably accurate model of a car which you can use to test on a virtual test track.

Basically every competent car manufacturer is doing this.

I have two questions:

1) does this hold for all 3 of jerk, snap and crackle, like OP suggested?

2) In applications where no humans are involved (robot actuators etc.), would it make sense to minimize jerk, snap and crackle too?

Modern cars are designed on GUI simulation software like MATLAB, they model head accelerations few inches ahead of the most important headrest and run optimizer on variables. If it can be made into equations, they can cancel it.

btw, minimizing higher orders of derivatives improve passenger comfort only so much if the driver isn't so good at look-ahead path planning, you can't make coffee cup rides not sickening by software.

>Modern cars are designed on GUI simulation software like MATLAB

MATLAB is the programming language. You are talking about Simulink. But there are also dedicated software packages for car multi body dynamics.

>you can't make coffee cup rides not sickening by software.

Plainly false.