After motocycles, cars and power products, Honda has taken up a new challenge in mobility – the development of a two-legged humanoid robot that can walk. The aim of the function for the robot in the human living space was to create a partner for people, a social robot. From this challenge came the HONDA ASIMO, Advanced Step in Innovative Mobility. ASIMO is designed to operate in the real world with its abilities to walk smoothly, climb stairs and recognise people's voices.
The ASIMO is scheduled for use in a pedestrian safety program named “Step to Safety with ASIMO”. This is a program where ASIMO will help students learn the safe and responsible steps to road-crossing using its human-like capabilities. Using ASMIO in this program is beneficial as such a robot will catch the attention of the young children and allow them to pay more attention to the safety steps being taught.
Besides this, ASIMO has been involved in many entertainment events such as performing for visitors at Aquarium of the Pacific, dancing with the host on the Ellen DeGeneres show and even walking down the red carpet for the premiere of the movie, “Robots”. The interactive nature of this robot has endeared itself to viewers from all over the world.
Videos of ASIMO in action can be viewed on the website at this link "http://asimo.honda.com/inside_asimo_movies.asp". It is fascinating how the movement of the ASIMO is so human-like, from the dipping of the shoulders to the turning of the hips when running. Look out for the particular video "NEW MOBILITY". You will be amazed by the human-like manner in which the robot comes to a stop after running. You can't help but be reminded of a human runner after you watch that clip.
Honda engineers created ASIMO with 26 degrees of freedom to allow it to mimic human movement as much as possible. For the technical part, we shall concentrate on the movement component.This robot’s walk is modeled after a human being with the human skeleton used for reference when locating the leg joints. The joint movement was calibrated after research carried out on human walking on flat ground and stairs. From there, the centre of gravity of each leg was modeled after that of the human body. Similarly, to obtain the idea torque exerted on the joints during motion, vectors at the joints during human motion were measured.
Besides this, sensors were also implemented. These were based on the 3 senses of balance that humans have, namely speed by the otolith of the inner ear, angular speed by the semicircular canals and deep sensations from the muscles and skin, which sense the operating angle of the joints, angular speed, muscle power, pressure on the soles of the feet and skin sensations. From this, the robot was equipped with a joint angle sensor, a 6-axis force sensor and a speed sensor with gyroscope to determine position.
To achieve stable walking, three main posture controls are used, namely floor reaction control which maintains firm standing control of the soles of the feet even during floor unevenness, target ZMP (Zero Moment Point where inertial force is 0) control which is the control to maintain position by accelerating the upper torso in the direction in which it threatens to fall and finally, foot planting location control which is the control using side steps to adjust for irregularities in the upper torso caused by the abovementioned target ZMP control.
Finally, a new two-legged walking technique allowed for more flexible walking by creating prediction movement control. For example, when humans wish to turn a corner, they will shift their centre of gravity towards the inside of the turn. With the Intelligent Walking Technology, ASIMO is able to predict its next movement in real time and adjust its centre of gravity correspondingly in preparation for any turns.
Pictures can be found at http://asimo.honda.com/photo_viewer_news.asp