Fixing the foot with an audience

Proposed ECU change

Current ECU

Proposed ECU with electronic engine speed governor.

Inside the workshop

And a shot of the Mantis packed away in the workshop

New workshop

It's a bit tight but I can just walk through the door!

5/6 legs nearly done

It's a pig of a job but worth doing.

I'm amazed I managed to get the EN8 axle stubs into my mini lathe and make half a good job of turning them down!

New Bearings

Need to replace some of the coxa bearings that are showing some corrosion! Also need to seal them up.

H&S operating the Mantis

Here is part of the H&S document I put together for Bestival 2012, this describes the working envelope of the machine, and operational practice.


Mantis Hexapod - Plan View Working Envelope

When the machine is powered up, the following applies:

RED: (No Go Area)

When the machine is powered up, under no circumstances should any personnel enter the Red area. Only when the machine is powered off or in a low power state can trained personnel enter this area.

ORANGE: (Leg Operational Area)

During normal walking operation the legs should stay within the orange area, but can be over-ridden under manual control by the operator to reach within the yellow area.

YELLOW: (Leg Reach Area)

The yellow area is the personnel clearance distance during operation. This represents a 3000mm radius from the leg coxa/hip joint that places personnel outside the maximum reach of a leg. 

When the machine is powered off, all areas are safe, however, if the machine is supported above the  ground by its own legs and without any prop stands, NO personnel should go underneath the body!

I've had a fair few requests for more information on the Mantis control system, so here is a schematic overview:

Mantis Control System Overview

Hydraulic maintenance

The hydraulic cylinder on the middle leg femur has a piston seal leak, this means the leg droops when it is powered off, and it also looses power when working. As the middle leg needs the most power I decided to switch the middle leg femur ram with the front leg femur ram..

Foot mould tests..

Having failed to find anything suitable for the foot of the mantis I decided to try making a mould and creating my own foot pads from polyurethane. This was the first mould and the first pour I tested. Unfortunately I got the quantity wrong, but it was a pretty successful test. I poured two types of hardness, shore 70 and shore 60, initial thoughts are that the shore 70 will work best.

The product I'm using for these feet is PT Flex 70. It's a fairly easy product to use, although the pour time is only 5 mins, so you need to work fast! De-mould time is approx 1 hour.