Robomech Walking Robot

For a change from model airplanes, I put together a Robomech model walking robot. Assembly was fairly easy, but getting the robot to walk without falling has been a challenge.  The instructions were pretty good, although not step-by-step, but rather included many steps for each diagram.  There was a good legend on top of the instructions identifying all the components.

 The kit consists of wood die-cut parts, plastic gears, metal framework for the electric motor and gears, and assorted electric components (battery holder, LED lights, and a switch). There is even paint, a small brush, and two pieces of sand paper included.

 Many small Phillips head screws used, and the instructions suggested a magnetic screwdriver or using Vaseline to hold a screw while trying to get it started, I ignored this advice and struggled.

 One place I would differ with the instructions is that I painted all the plywood pieces, before assembling. The instructions have you completely assembling the robot, and then painting, this would be tough.

Teaching the Robot to Walk

 Mpeg video 2.6 mb of Robot Walking

There is a small picture on the outside of the box with a picture of the gears, text next to this says, “Learn about Gears”.  You can easily see that there is a combination of small and large gears that greatly slow down the electric motor to power the legs and arms. The greatest learning I had was getting the robot to walk, without falling over. The feet consist of  two U-shaped metal brackets that are held to the legs with two small screws.  The brackets face towards each other, so the feet are between the legs. First issue I tried to correct was that the robot would fall over to the right or left, it would also fall on its face or back also.

First Major Attempt at Correction

 My first major step in correcting the problem, was to re-attach the U-shaped brackets such that they were facing towards the outside of the legs. This gave the robot stability, but it could barely walk now. It waddled severely from side to side and made very little forward progress. To me, this was not a proper solution, so I put the brackets back. Next, I experimented with bending the brackets in different directions, to see if it made a difference. Not really. My next attempt was to make additional small wood feet that are on the outside of the legs.  This seems to have solved the problem of the robot falling to one side, but it can still fall forwards or backwards.

Get a Grip

 Watching the feet closely, it appeared that the feet were slipping at times.  I thought I would try gluing sandpaper on the bottom of the feet. Not sure how much this has helped, but I think it has helped slightly.

 More Observations

 I am still not pleased that the robot occasionally tips over. Most  of my testing has been on a hard surface such as vinyl flooring.  I tried the robot on carpet a couple of times, and it flew over almost instantly.  One theory I have is that there is too much weight high in the body of the robot, causing it to easily tip over.  Putting additional weight in the feet, might be worth a try.

 Another part of my debugging procedure has been to carefully observe the positions of the feet as they cycle through. I identified a point where the back of the foot was pushing the robot up, at one small edge.

Next Steps

I believe more testing is needed, the following are ideas that I would like to pursue:

• Try the robot walking on additional surfaces such as concrete, most testing has been on vinyl flooring.

• Video tape the robot walking and play in slow motion.

• Tape a lead sinker on each foot for weight.

• Extend the front and the back of the wood feet slightly.