ArtBot

A walking gait for a depressed robot

I wanted to create a new gait that you will not find anywhere, a gait for a “depressive robot” (well the robot is not depressed of course, it just imitate the posture of a depressive person).

It is also an interesting research work because one have to coordinate the whole body in order to create an emotion from the audience. Besides it is a good opportunity to play with the articulated torso of the robot.

Unfortunately I cannot like cartoonists, exaggerate all the postures in order to create amazing walking gaits and create stories around them.

But for a first tentative I am quite satisfied - yes always good to congratulate myself ;)

Improvements on the straight walk and new turning gait video available

New video on the Straight walk gait

This video shows some important improvements with respect to Video 2: no more fast movements of the torso during heel strike and smoother transitions from one phase to another.

More details on the walking gait computation.

Over the last months, I redesigned some parts of the robot (see Figure 1), mainly:

• The Pelvic and the brackets “linked to the Pelvic” are made with aluminum. Initially the Pelvic and related brackets were made of resin, but because of the torque exerted by the servos and the weight of the robot, they bent which lead to difference in terms of angles (Pelvic in Sagittal plane to be precise) between the simulator and the real robot. The use of aluminum solved the problem
• The lower part of the leg and the foot in order to change the distribution of weight.

Two New videos more compelling

Here are two new videos I want to share. The first video shows the robot walking at real speed.  The gait is quite stable and the video shows two cycles and the second part focus on the legs movements.

As mentioned before the gait I implemented is different from the one used by most of the existing humanoid robots. Here the gait implements a heel strike, a forefoot push and the stance leg is straight during the swing phase. In other words, the robot never keeps the knees bent.

 

The second video shows the same sequence but a speed 4 times faster, it is interesting because  it looks more "natural and/or more smooth" I will say.

 

I will post a note describing the robot and how I implemented the gait very soon

 

Human gait cycle : importance of the stride length

So far we did not speak about the stride length, which is defined as the distance between two successive placements of the same foot, but it is the parameter that will determine whether the gait is slow, medium or fast.

In our study we will consider that stride length will be determine by the following parameters:

• Rotation of the pelvic in the Horizontal plane ;
• Thigh/Hip flexion in the Sagittal plane;

Human gait cycle : some graphs

Here are some graphics in the different planes in order to illustrate what have been discussed in the note “A study of the human gait cycle in order to design a biped robot”.

 

A study of the human gait cycle in order to design a biped robot

To make a biped walking machine, it seems to me essential to understand as we walk. This is precisely the aim of the study. It differs from other studies because the pelvis and chest (pectoral girdle and arm) are taken into account.

1      Take a closer look at human gait

1.1    Introduction

Biomechanics defines walking a form of bipedal locomotion as there is an alternating action between lower extremities. One leg is in touch with the ground for restraining, supporting and propulsion.

The other leg is in swing phase for creating a new step forward. So gait is the result of a series of rhythmic alternating movement of arms, legs, and trunk which create forward movement of the body.

By convention, the gait cycle begins with the initial placement off the right heel and ends when the same heel contacts the ground.

La marche c'est aussi raconter une histoire

Quand on observe déambuler quelqu’un dans la rue, nous avons souvent de nombreuses images qui nous viennent, cette personne est-elle heureuse /malheureuse, riche/pauvre, exerce une profession manuelle/intellectuelle, jeune/moins jeune/vieille, agréable/acariâtre … car quand on marche, l’ensemble du corps raconte une histoire.

Pour le démontrer on va s’inspirer des animateurs. Ceux sont d’excellents observateurs dont l’une des tâches est d’exagérer certaine expressions des caractères qu’ils animent dans le but justement de susciter une réaction.

Dans le cadre de ce travail, nous sommes exactement dans la même perspective. Ce qui nous différencie des animateurs, c’est la réalité.  Les animateurs ne sont pas soumis aux lois de la physique, ils en jouent même souvent pour créer des situations qui nous feront rire en général.

Une étude de la marche dans le but de concevoir un robot bipède

1      La Marche

Pour réaliser une machine bipède qui marche, il me semble indispensable de comprendre comme nous marchons.

C’est précisément le but de cette étude. Elle se distingue des autres études par le fait que le bassin et le buste (ceinture scapulaire et bras) sont pris en compte.

Cette étude sera régulièrement enrichie et une version en Anglais est également prévue