Re: [mowbot] Locomotion/chassis

Dave Everett (Deverett nospam at
Wed, 25 Sep 1996 15:20:02 +1000

robin nospam at wrote:
> Dave Everett <Deverett nospam at> wrote:

> > Firstly I see you opted for only one skid, what happens when the robot
> > reverses?
> If the centre of gravity is at the point marked ``c'' and low enough,
> there isn't a problem.

Not if the robot is climbing any sort of grade though.
> > ... just move the axle forward about half way and place the castor > > at the rear. Of course doing this negates the ability to perform > > turns in the robots own diameter
> It seems to me that this is quite a disadvantage, since the algorithm
> for getting out of confined spaces has a lot less freedom. Not that it
> is impossible of course, but it does mean you need a lot more collision
> sensors and a clever backtracking routine.

Nothing particularly clever is needed.
> > I would suggest that a slightly more rectangular or square base
> > would be more suitable as it will allow us to 'thin' the robot to the
> > width of the axle base.
> Once we know the width of the cutter, it should be more obvious whether
> the chassis can be circular. Since the cutter is going to be relatively
> light, we might be able to put it in the otherwise empty space forward
> of the drive wheels:
> ___
> .- S -.
> / c \
> | D D |
> \ xxxxx /
> `-___-'
> front
> This does have the potential problem of grounding that Dave mentions.
> Though as we might well want to dynamically adjust the cutting height,
> the cutter can perhaps be lifted out of harm's way in these circumstances.

The prime spot for just about everything seems to be along the axle
line. Both cutter and grass sensors would benefit from being there, but
I can't yet see how we would be able to have them coexist peacefully.

Dave Everett.