[Dprglist] Fwd: My Robot Chassis Dynamometer

[David]

Forward from Dave Ackley

dpa



-------- Forwarded Message --------
Subject: 	My Robot Chassis Dynamometer
Date: 	Tue, 22 Jun 2021 21:12:34 -0500
From: 	David Ackley <dackley at verizon.net>
Reply-To: 	dackley at verizon.net
To: 	'Anderson, David' <dpa at mail.isem.smu.edu>



Hi David

I found the email I had sent you and modified it for the DPRG mailing list.

I tried sending it via the DPRG list, but it didn’t seem to go out.

So I’d appreciate it if you would send it out to the DPRG mailing list.

Thanks

Dave

*From:* David Ackley [mailto:dackley at verizon.net]
*Sent:* Tuesday, June 22, 2021 9:05 PM
*To:* 'DPRGlist' <dprglist-bounces at lists.dprg.org>
*Subject:* My Robot Chassis Dynamometer

Hi All

My “Robot Chassis Dynamometer” is what I tried to show at the 9/24/2020 
VRBNO meeting, but I’m not sure whether it ever showed up when I was 
discussing it or that people followed my description.

Just in case it didn’t show up I’ve attached a picture of the bare 
“Robot Chassis Dynamometer” and a picture of my “Build-More-Robots” 
robot sitting on it that I’m going to try tuning the PID on.

I really like the size, cost, and characteristics of the 
“Build-More-Robots” robot, so I have several different versions of it.

I decided that what I really wanted was a way of running this robot in 
place while analyzing and tuning up its  PID.

So I came up with the idea of building a “Robot Chassis Dynamometer” 
where load/inertia on the robot’s wheels is a reasonable approximation 
to what the robot would see if it was actually running around “In-The-Wild”.

In theory, the inertia that a robot’s wheels see is roughly the robot’s 
mass (Mr) times its wheel radius (Rr) squared

(i.e.~ Mr*Rr**2).

So I built a “Robot Chassis Dynamometer” with two flywheels that the 
robot’s two wheels drive that try to approximate the effect of the 
robot’s inertia.

The inertia of a solid flywheel is */one half/* its mass (Mrcd) times 
its radius (Rrcd) squared

(i.e. ½ Mrcd * Rrcd **2).

So I got a chunk of metal with a suitable mass and radius such that its 
inertia approximates my robot’s mass and wheel radius to build the 
“Robot Chassis Dynamometer” shown in the attached pictures.

Enjoy

Dave

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