Humans - Walking

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Research

http://www.dartmouth.edu/~humananatomy/part_3/chapter_18.html

When a subject is walking on level ground, the movements of the lower limbs may be divided into "swing" and "stance" phases, which are separated by heel-strike. The swing phase occurs when the limb is off the ground, and the stance phase when it is in contact with the ground and is bearing weight. A cycle of walking is the period from the heel-strike of one foot to the next heel-strike of the same foot.

At the time of heel-strike, the ankle is in slight dorsiflexion (fig. 18-2) and the anterior leg muscles contract in order to prevent the forefoot from slapping down. The muscles progressively relax to lower the foot and weight is transferred up the lateral side of the foot and then across the ball of the foot as the stance phase progresses. The last part of the foot remaining on the ground is the medial part of the ball of the foot and the great toe. This is termed “toe-off” and begins the swing phase.

At the time of heel-strike, the knee is slightly flexed on that side, with contraction of the quadriceps necessary to prevent collapse. As the stance phase progresses, this knee straightens, resulting in some upward motion of the trunk.

During the stance phase, the thigh abductors, particularly the gluteus medius and minimus, are active on the side of the leg that is in contact with the ground. This is in order to resist the tendency of gravity to cause downward movement of the hip on the opposite side (fig. 18-3). Additionally, the paraspinal muscles and lateral trunk muscles are active on the side of the swinging leg in order to resist downward movement of the iliac crest on that side.

The center of gravity moves upward and downward twice during each cycle, as is indicated by the bobbing up and down of the head. That is, the body is lifted as each limb is extended during its stance phase (fig. 18-2). There is also a slight side-to-side movement. The basic movements involved in walking are (1) flexion and extension at the hip, knee, and ankle joints and at the front part of the foot; (2) abduction and adduction, chiefly at the hip joint (fig. 18-3); and (3) rotation, mainly at the hip and knee joints.

http://www.dartmouth.edu/~humananatomy/figures/chapter_18/18-2.HTM

http://www.dartmouth.edu/~humananatomy/figures/chapter_18/18-3.HTM

(Related to the above excerpt) Figure 18-2. The swing and stance phases of the right lower limb

(Related to the above excerpt) Figure 18-3. The hip joint viewed from behind when walking

Article on bipedalism from the database 'Infobase Learning':

http://www.fofweb.com/activelink2.asp?ItemID=WE40&SID=5&iPin=EEVO0027&SingleRecord=True

Animals that walk habitually upon two legs are bipeds, and this ability is called bipedalism. As any dog owner or anyone who has visited a zoo knows, many quadrupedal animals (animals that habitually walk on four legs) can stand on two legs for a brief time, and perhaps even walk on two legs. Some apes, such as chimpanzees, are partially bipedal. Their form of locomotion, called knuckle-walking, involves long arms and the use of their knuckles to help them maintain their posture. Only humans and birds are fully bipedal among modern animal species.

Adaptations required for human bipedalism include:

Strong gluteus maximus muscle. The largest muscle in the human body is the gluteus maximus, which connects the backbone and the femur (thighbone or upper leg bone). By contracting, this muscle pulls the backbone into an upright position. This is one reason why humans have big butts, compared to other primates.
Foramen magnum underneath the skull. The foramen magnum is the opening in the skull through which the spinal cord connects to the brain. In quadrupedal animals, this opening is in the rear of the skull, but in humans it is at the base of the skull.
The pelvis. The pelvis (hip bone) of humans must support most of the weight of the body and has a shorter, broader shape than is found in quadrupeds.
The knees. The knee joint must be able to extend to make the femur straight in line with the tibia and fibula (lower leg bones).
Angle of femur. The femur of humans angles inward, while in chimpanzees it does not.
The foot. The human foot has an arch, and a big toe that is in line with the others. In contrast, chimps do not have arches, and their big toes are at an angle resembling that of a thumb. The thumb-like big toe helps chimps to grasp branches while climbing trees, something not necessary to a bipedal animal walking on the ground.

'Science Dong A' volume 257 p56-61; published in 2007 May 1 by Dong A Science (Korean):

Yoo, JaeJun. "Scientific View on Ducks, Penguins and Humans' Gaits; Shifts in Center of Gravity and Energy-minimizing

Strategies." Science Dong A. Vol. 257. Seoul: Dong A Science, 2007. 56-61. Print. Science Dong A.

https://www.youtube.com/watch?v=vq9A5FD8G5w https://www.youtube.com/watch?v=G8Veye-N0A4

Slow motion reference video of a male walking. Slow motion reference video of a female walking.

Guide:

http://www.vmg.vil.ee/Robootika/Lego9695/9695_Humanoid100.pdf

'Building robots with Lego Mindstorms NXT' from the school library

Astolfo, David, Giulio Ferrari, and Mario Ferrari. Building Robots with Lego Mindstorms NXT. Updated ed. Burlington, MA:

Syngress, 2007. Print.

Robot Building

1. Following the guide I've found from the interent, I started building the robot.

I've finished making the base of its legs.

2. I've added the motors, gears, etc. Then I tried to modify the design.

3. I've made further changes to the robot while following the design from the guide. As a result, the robots looks almost exactly same as the design except that I've drawn out unnecessary parts (e.g. arms).

4. After some experiments I've learned that one motor moves the legs up and down and the other one moves legs forwards and backwards. From what I've noticed, I programmed the robot.