Newsgroups: comp.robotics
Path: brunix!sgiblab!swrinde!ihnp4.ucsd.edu!ames!sgi!wdl1!mail!cps233!dombrows
From: dombrows@lds.loral.com (Brian Dombrowski, 5424)
Subject: Re: tennis robot
Message-ID: <1994Apr22.162603.10286@lds.loral.com>
Sender: news@lds.loral.com
Reply-To: dombrows@lds.loral.com
Organization: LORAL Data Systems
References: <Brian_Sullivan.29.2DB6C0B1@Carleton.CA>
Date: Fri, 22 Apr 1994 16:26:03 GMT
Lines: 27

In article 2DB6C0B1@Carleton.CA, Brian_Sullivan@Carleton.CA (Brian Sullivan) writes:
> >> Tennis Ball Server:
> >> 
> >> Two electric motors each drive a 5" diameter wheel in opposite directions
> >> ( the left one clockwise, the right one counter clockwise.)  The wheels
> >> are placed so that the distance between them is about 1/2" less than the
> >> diameter of a tennis ball.  A ball feed ramp directs a tennis ball to
> >> roll between the two wheels.  The ball is pinched between the wheels
> >> and is shot out the other side at 60 MPH.  ( see figure 1 below )
> >> 
> 
> OK I've read a few of the replies to this post, but ....
> 
> If I recall 60 mph is ~ 88 ft/second. The 5" wheels will need to turn ~ 10-12 
> cycles /sec. or 600-700 rmp. At that speed the thing is going to have a 

Assuming the ball acquires the speed from the radial velocity of the wheel
you need over 4000 RPMs to get 60 MPH out of 5" diameter wheels.

5" diameter wheels have a circumference of 15.7".  88 ft/sec is 1056 in/sec.
That's 67.3 revs/sec or 4038 RPM.


Bd



