I thought the 2+dof idea had more to do with the theoretical ability of the walking mechanism to allow for variable motion of the legs not just the same action repeated over and over again as the cams and leavers ran through their fixed pre programmed sequence.
Even if this walking sequence moved the leg in combinations of XYZ axes there is no freedom, the sequence can only run back and forth fast or slow if the foot only lifts 10 mm and it comes to a 20 mm step there is nothing it can do about it.
I thought that was why multiple linear actuators were one of the favoured theoretical
Methods put forward by the proponents of “true” walkers.
The problem I have with that is that those people insist that the mechanical parts of the bot be built for this flexibility of movement and then its ok to use a simple code looped through the electronic control to power the actuators.
Brett told me I could use an electromechanical rotary switch to control the walking sequence he even suggested one out of my broken dish washer.
My point is that if the walking sequence is controlled in this manner it has no more freedom than if it were controlled by a system of cranks and levers.
To go to all that trouble and compromise the robots ability to survive a fight for what??? The illusion that that with enough sensors accelerometers gyros motor controllers and computer power it might have made it over that 20mm step.
I think it is possible to come up with something better.

2 DOF requires 2 motors. one for each direction you want it to go in. In human terms the shoulder joint has 3 DOF, the elbow has 1 Dof and the wrist has 3 .
In bot terms it means a joint that can pivot two different ways. Lifting leg is one and swinging it back is another. each requireing its own motor or actuator. One works on the pitch whilst the other on the yaw. Adding a third would give you roll and making it a 3 DOF leg.
In order for some bots to lower their overall height they have another DOF on shoulder to enable this meaning another motor on each leg. Every DOF requires a motor and thats why shufflers are different. An Inverse Kinematic system, camms, chains and multiple linkages are 1 DOF only. You would have to duplicate your system, slant it on another angle and then it would be 2 DOF if you could get it to work. If you also had a movable knee joint and an ankle That would be another 2DOF your legs would have..
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quote:

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Originally posted by MachineHead:
2 DOF requires 2 motors. one for each direction you want it to go in. In human terms the shoulder joint has 3 DOF, the elbow has 1 Dof and the wrist has 3 .
In bot terms it means a joint that can pivot two different ways. Lifting leg is one and swinging it back is another. each requireing its own motor or actuator. One works on the pitch whilst the other on the yaw. Adding a third would give you roll and making it a 3 DOF leg.
In order for some bots to lower their overall height they have another DOF on shoulder to enable this meaning another motor on each leg. Every DOF requires a motor and thats why shufflers are different. An Inverse Kinematic system, camms, chains and multiple linkages are 1 DOF only. You would have to duplicate your system, slant it on another angle and then it would be 2 DOF if you could get it to work. If you also had a movable knee joint and an ankle That would be another 2DOF your legs would have..

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Yes I aplogies again for my use of the word Axis. It was late I was tired blah blah, THanks Kheeroo for your words but have to disagree on your shouder not being able to twist. documents suggest there is 90 degrees of twist in your shoulder as in your wrist but being a ball joint would make it hard to notice slight movements, but if you twist your arm like a screwdriver you shoulder joint will twist as well, just not as much. Well said about the stabilising effects, it made me think of mechadons legs and how close the motor/actuators angles are to each other. THats a good example having about 14 motors. 2 on each leg i guess and a few on its body.

Have to clarify something I said. quote - (XYZ is not 3DOF). In one way you can have 3DOF on the XYZ but was trying to explain that in XYZ environment you can also have a robot that has 30 DOF as each degree of freedom is independant from the other and doesnt have to refer to the XYZ of the environment because its position is in relationship to the part its connected to.
It has a sort of a Parent/child relationship, apart from the example above of a shoulder joint i guess.
I think the key word here is freedom, degrees of FREEDOM. If your mechanism is not able to work on any other plane than the vertical then it can have only one degree, think about it. As soon as you put another motor on the same leg at a different angle, even something small like 20 degrees you have a second degree of freedom and as Kheeroo said you become more stable, not that you have necesassily increased your range of movement much but you have reinforced the whole leg.
As Mel once said "Freeeeeeeedooommmm"
Degrees of Freedom -
Wanted to thank everyone for keeping this subject on track and not being too hard on my errors along the way.
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I made a comment about having 2 DOF on the Hip and got to thinking and realised there was nothing to support the idea that it was limited to the hip joint. A leg with a hip joint and a knee joint is a 2 DOF leg as well so have to ask if anyones has the international rules on the walker bonus in any format.
Curious to see how it is worded
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According to the RFL ( www.botleague.com ) which is the ruleset used in most american comps..

Methods of mobility include:
3.1.1. Rolling (wheels, tracks or the whole robot)
3.1.2. Walking (linear actuated legs with no rolling or cam operated motion)
[Contact this event with questions on weight bonuses to see if your robot may qualify. Robots are classified as "walker" at the sole discretion of the Event Organizer, and are not subject to appeal.]
3.1.3. Shuffling (rotational cam operated legs)

Thats what the RoboWars rules are based on...

So that says Son of Whyachi/Drillzilla style things are shufflers, Mechadon is a walker and everything else is dependent on the event organiser. So whoever wrote those rules left the hard work for someone else.
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or couldnt be bothered trying to see a clear consensus between all the emotional angst in the walker debate.. besides which, in most cases, most walker are allowed to compete regardless of the rules/weight bonuses because they're "cool" and will entertain the crowds.

So with those rules, Build something cool, and regardless of what it weighs, the Event Organiser (presumably inclduing the approval of the other competitors) can allow it to compete.

or build another SOW or other rule-exploiting bot that only vaguey looks any different to a rolling robot, or a wind-up toy and the EO can put you in with the bots in the same weight class.

seems like a reasonable compromise to me.. for now anyway, until someone builds something cool enough to make another exception for..

For a Robot that never won a fight, Mechadon sure created a lot of controversy..

ACtually it did beat Ginsu once. Ginsu was on its side and Mechadon was stuck on the wall but still got the win but couldnt do repairs and forfeited.
THats fair enough about the rules, was hoping there was a document referring to the 2 DOF clearly from an international source that migt have been a useful starting point. Looks like my idea of drivers in the ring sorting this out might be the answer, no flame throwers please.
Was hoping the the Star wars walkers might qualify as they have hips and knees, Since doing a google search have diff ideas about walkers but will probably just walk off a cliff instead.
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Hehe, a real Mechwarrior!

http://www.sakakibara-kikai.co.jp/products/other/LW.htm

Shame that the guns are only air powered
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All my robotic dreams are comming true lately...

now the next step.... to use 'dead' soldiers to operate Dreadnoughts..
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Sweet. Looks a bit like a fire fly from MW3. There is another website I've been to that a guy is making a hydraulic powered mech. I'll trying to dig up the link.
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https://www.halfdonethings.com/

Give it proper cannons and a rc unit and you've got yourself a whole new class
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best quote ever:: "Those Gas-Turbine style warehouse heaters arent illegal, and neither is remote controlling one as far as I know."

(at the risk of fanning old flames)

That thing isnt a walker..

it doesnt even lift its legs, it just slides them along..
probably some form of one-way clutch in ordinary wheels hiding under the skin.

Several suspicious perspective changes during the video clip lead me to believe that at least some of it has been faked.

The view of the cars in the car park look way too high compred to the height of the thing when the guy climbs into it.

No sound during the walking clips, but the sound of some brigg's'stratton sounding-ish lawn mower engine chugging away during the "weapon" firing (bursts of compressed air) clips is suspicious as well..

Sorry to be a a wet-blanket.. it looks cool and all, but it doesnt quite smell kosher to me.. might be another "Valerie the Android"..
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I would say that that thing is a prime example of a shuffler. It's feet clearly do not leave the ground.
That thing just reinforces my view that the japanese view robot building as an art form with at least 90% of all robots built over there having no real use. A good example is an all terain "hopping" (walker?) robot built by a group of university students which will be used to find earthquake victims and "comfort them".

Anybody notice that the view from inside the cockpit seems to from at least 3 stories high?
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