ASIMO in Prague

ASIMO (Advanced Step in Innovative Mobility) was presented to public in November 2000. It is a successor of heavy machines P2 and P3 — ASIMO is smaller (120cm) and much lighter (52kg). Some resources speak even about 43kg, which were achieved with another banting. ASIMO has 26 degrees of freedom. It is able to walk as fast as 1.6km/h or climb stairs. It can carry small objects up to 2kg in each hand. The power is provided by a 38.4V/10AH NiMH battery that can keep the robot alive for 30 minutes. The robot height allows common interaction with the environment. Due to its 120cm it can reach switches, door-handles or a keyboard on the table. The sensor pool contains for example two cameras, accelerometer and gyroscope.

The presentation was targeted at journalists (i.e. amateurs). After a short opening talk the robot appeared from behind the corner with flowers. A hesitating moment and then a person from National Museum accepted the flowers. He lay them down near the bust of Karel Čapek, the author of the R.U.R. Then the robot walked approximately to the middle of the room, where it presented its tricks. It was pity, that we did not notice before two black and white calibration marks on the floor, used for precise robot positioning. We could have chosen a slightly more attractive spot.

Moderator of the show was a representative of Honda development laboratory, which designed the robot. Comments were mostly restricted to announcements of what is robot going to do, so they did not contain any, for us robotics, “useful” information.

The demonstration of various types of walking was followed by climbing the stairs (up and down). The robot did not really fancy that task. It stopped so it almost looked like it is thinking. The reason for this pause were camera flash lights. Although all participants were warned (both in Czech and Japanese) not to take any pictures with a flash during this presentation, they ignore it. ASIMO tried to compute its exact position using black and white marks in front of the stairs, and it probably could not see them very well. Similar marks were also on the ramp, from which robot later walked down. A big hint for how the walking algorithm works was a comment of the moderator, who in the very moment when robot started to climb down the stairs swept his hand and let people take pictures. This fact shows that the robot probably does not use cameras during the walk, but only beforehand for positioning. The step size must be entered via some alternative way. This fact interested us so we searched for more information.

Although the first impressions were not so positive, later we found some more interesting details. It was almost herculean task, to find out how the robot works “inside”. One of the better resources was ASIMO_Technical_Information.pdf.

Ordinary people could say – well it walks, so what... At first sight it is hard to see all the details, which had to be successfully solved. It is pity, that Honda restricts its presentations to statements, that ASIMO is the best humanoid robot ever. They probably use motto that if you do not commend yourself nobody else will. The official web pages http://asimo.honda.com/ are slightly more moderate and speak about the robot ASIMO as “one of the best”.

So why is ASIMO “so good”? One of the details worth mentioning is, for example, usage of small projections on ASIMO's feet. Studies of a human walk showed that construction of a human body contains many such a “soft” elements. The main reason for them it to protect our joints against too much pressure. Notice how important are for our health good shoes for sport (basketball, run, etc.). Our joints survive thanks to these elements without damage. Without these “dampers” the joints would have to be much bigger otherwise our speed would be limited to 1.6 km/h and we could only dream about jumping. ASIMO's small elastic projections are a simplified version of these human mechanisms.

Another reward of the furious search was a discovery that ASIMO is using accelerometer and gyroscope for its movements. These sensors are mounted on the robot body and provide information about actual pose of the torso. Robot also uses encoders built in each joint. Finally it has a 6axis force sensor in each hand and leg, measuring stress in all extremities.

Unfortunately we did not find out what computer robot ASIMO controls. It could be a very powerful computer guessing from the size of “backpack”. The predecessor P3 had four-processor high-performance system, so we can expect something similar.

Honda is above all proud of its own walking algorithm, which has been seriously improved when compared to older robots. Already robot P3 was able to walk relatively well (as you can see on several video shots), but only forward or to turn in place. Its walks is built from several prepared patterns, which are then sequenced. The result is unnatural walk — it has to stop whenever it wants to change direction.

ASIMO's walk algorithm contains more reactive behavior. In every step it takes into account its inertia and it can compute/predict, in what state it will be in the next step. If this state does not corresponds to desired state, it can modify length, speed or direction of the next step to improve it.

One of the consequences is that ASIMO can, for example, walk in a circle. The research showed that if a human wants to turn during the walk then he/she slightly leans in the direction where he/she wants to turn and only after that it starts to turn. This is something what ASIMO ancestors were not capable of. During the sequence they could not change neither speed nor step length.

ASIMO's ability to react to the environment was the biggest disappointment for us. Later we found out that robot uses camera only for searching the marks (as you can see on the picture), and it can climb only stairs, which were beforehand measured and exactly marked.

According to http://world.honda.com/news/2002/c021205.html ASIMO can use camera for gesture and face recognition. If it sees known face it can greet. It can recognize when a human wants to shake hand. It is easy to doubt the reliability of these relatively new features. Nothing of this was presented in Pantheon, and robot refused to shake premier Špidla's hand for the second time. Some newspapers used this to state, that premier Špidla is probably not very sympathic to the robot ASIMO, but the reality is surely much simpler — either robot was preprogrammed to shake hand only once or the routines are not very robust yet.

We could write long stories from our own experience about how difficult it is to reach some level of reliability of robot that has to move in a beforehand unknown environment and react to it. Therefore it would by proper to say that despite of our somewhat critical comments have Honda developers built an exceptional robot.

If you have any comments of questions – kontaktujte nás. More information about the robot ASIMO can be found on these pages: