[swordtart]

In retrospect I think the body movement happens when the opposite leg pushes the vehicle forward. The other rear leg becomes the pivot. In an animal the body will flex and probably twist diagonally somewhat but the rigid nature of the box on top will prevent too much flexing with the MUTANT. You could resolve this with the body making a 15 degree turn with each movement rotating about the non stationary foot, but equally you could just say that hydraulic linkages between the cab and the chassis takes care of all that.

Your example gait is not so much a walk as a shuffle. It is the machine moving forward and then coming to a rest position in stable equilibrium. A walk is a constant fall forward arrested by moving the supporting limb underneath the new centre of gravity and whilst it ends in a stable position when you stop, while moving it is unstable.

This first movement turn shown has each leg effectively moving forward from the centre point, but as the quadruped body moves forward the point of suspension moves ahead of the feet in contact with the ground and so each step is actually a move front a point behind the point of suspension to a point in front. So once you are actually moving if the body moves further then so will the foot, this is how stride is increased which is how quadrupeds move faster.

You can go at 20 without changing the foot placement, just changing the rhythm a little into the Amble. There the front feet move as the rear foot arrives allowing it to step into the front foots place. In this case you move the body 1" forward with each leg movement instead of the 1/2" with the walk.

The trot is where only two legs are in contact at any one point and as this involves a degree of bouncing, I am not sure it really works for the MUTANT, the body would move 30 mph and so each leg must move 3". It is in this bounding that the front legs move to a position in front of the body. In elephants the gait is especially adapted as they can't really jump. Instead the rear legs walk and the front legs trot. This results in the centre of mass remaining around the same height as it moves rather than moving up and down like a trotting horse. This may be more appropriate for the MUTANT. How this happens is probably irrelevant (I think it like the Tolt of Icelandic Horses) as we are only concerned where the feet land each phase. In the first cycle move one of the front legs an extra inch. In the following cycle move the back leg on that side an extra inch into the created gap and this time move the other front leg the extra inch, the next cycle that back leg can be moved into the extra space etc.

It is hard to see how you could go faster without bumping into your own limbs unless you change the gait again to the Canter. Here a rear leg moves first. You move the body 1" as usual. The next movement is both the other rear leg and the opposite front leg. The Body moves another 1" forward. The final step is the remaining front leg and this time the body moves forward again on the lone front leg step . The sequence is then reflected for all three movements to complete the cycle. As the body is moving 3 times each turn each leg can extend 1" beyond that new suspension point making extra space for the leg moving into the gap (I think this works). These 3 movements would go in phase 1,3 and 5 of a 5 phase turn and equate to 30 mph

You can change the gait to the Gallop where only one leg is in contact with the ground at a time. You will move the Body forward after each leg moves and thus get 4" of body movement per turn. This equates to 40 mph of movement.

If you step longer (longer legs and body) you could double all these movements.

If this is more complicated than you would like (and it is pretty complicated I agree), you could hand wave it all away and just move the feet further each phase (by half the total movement in inches) and move the body by the same amount each time a back foot is moved. It is a machine after all, perhaps it doesn't matter about energy efficiency. This achieves the same range of movement but avoids having your MUTANT tap dancing :)