Well your in luck! I specialize in character animation! Man, I can talk all day about that subject. Well, here it goes…
First off you must remember that a walk is never the same for each person and also projects their character. For example a woman who is self reserved is going to take smaller and tighter steps. While a big macho man is going to strut his stuff and take wide pounding steps. Also if the character is happy, sad, angry, or drunk their walk is going show it. Happy walk has a lot of bounce in the step, so the torso is going to be moving up and down quite a bit. Sad walk is more dead hardly any moment in the torso and it is slow. Angry walk has arms swinging and feet slamming on the ground as the character stomps around. And drunk walk…well you get the point.
Now the first thing you want to do is to change your timeline to 24 frames per second. Trust me, it is far easier to think in 24’s than it is to think in 30’s. Now walks are normally on the dot and do not vary in time when the person is walking. for example, the most common walk is every 2 steps a second. So thats one step for every 12 frames (15 frames if you are animating on 30 fps). mainly here is the break down:
4 frames = a very fast run
6 frames = a run or very fast walk
8 frames = slow run or cartoon walk
12 frames = natural walk
16 frames = strolling walk
20 frames = elderly or tired person
24 frames = slow step
32 frames = I’m…almost…dead
Now that you know the speed lets take a look at the action. The heel of the foot always leads the toe and the rest of the foot. For example, the heel rises and before the toe does went the foot is about to take the next step. The heel also touches the ground first when the character actually takes the step. Also the toe of the foot stays on the ground until the last moment then the foot swings to a up position barely missing the ground just as the heel hits the ground. Are bodies spend as little energy as they can when walking, so the feet are barely above the ground. That is why it is so easy for us to trip over the slightest crack in the pavement.
So basically it goes like this:
1Heel moves up toe stays on ground (other foot is on step 4)
2foot starts to move forward as toe leaves the ground
3toe swings up as heel makes its way down
4heel touches ground first (other foot should be on step 1 at this time)
5then toe touches ground.
Now you have your feet animated lest talk about the torso.
The torso can do just about anything when the fee are passing each other but when both feet are on the ground the torso is aligned with the feet. Also when the feet are making there pass from the foot in back to the foot in front the torso is up a little higher. So we get this bouncing affect when the character walks. It mostly depends on what mood your character is trying to portray.
Its hard to teach this subject without you being right next to me. The best way to find out how a body moves is to grab a stopwatch and go people watching. Walk behind someone and try to copy there walk and pay attention to where your body is. Most of the time I act out what my character is going to do before I animate them.
Once you completed one cycle of the animation you can just copy the keys so your character’s walk is just repeateing. If you do it right, i will look natural.
I hope this helps you and good luck!