ASIMO – The World’s Most Advanced Humanoid Robot

Two ASIMO robots competing in soccer

(By, Kevin Le)

20 years in the making, Honda’s robot, ASIMO (Advanced Step in Innovative Mobility) is the most advanced humanoid robot in the world.  Capable of understanding a series of preprogrammed gestures, phrases, commands, ASIMO can also recognize voices and faces and interface with IC Communication Cards.  Standing at 4 feet 3 inches (1.3 meters), ASIMO is meant to be a non-intimidating helper to people and is often described as a “kid wearing a spacesuit.”  ASIMO can do jobs too dangerous for humans to do, such as fighting fires, entering hazardous areas, and even disarming bombs.  The three main and most incredible functions of ASIMO is the robot’s ability to walk independently and maintain balance, its smooth motion, and its senses.Kevin Le

One of the things which make ASIMO so unique is the robot’s ability to walk independently.  Engineers at Honda developed ASIMO’s walking mechanism by studying the legs of insects, mammals, and the motion of a mountain climber with prosthetic legs.  To create ASIMO’s body movements, many things had to be taken into account, such as how humans shift their weight and use toes to balance themselves.  In fact, ASIMO has soft pads underneath each foot which act as “toes” and also act as shock absorbers.  Like humans, ASIMO has hip, knee, and foot joints and has an incredible 34 degrees of freedom (a degree of freedom is how engineers refer to joint movement in robotics).  ASIMO also has a speed sensor and gyroscope sensor which allows the robot to not only know where and at what speed the robot is going, but also relay information back to the central computer to help ASIMO stay balanced.  Through the implementation of floor surface sensors and six ultrasonic sensors, ASIMO can also “see” its surroundings and react accordingly.  To control the “muscles” of ASIMO, ASIMO has both joint-angle sensors and a six-axis force sensor.  By using knowledge about the Earth’s inertial forces and the zero moment point (ZMP), which is what happens when forces balance out, ASIMO is also able to make turns fluidly without having to shuffle around.  To monitor ASIMO’s posture, the engineers designed ASIMO around three areas of control: floor reaction control (can stand on uneven surfaces), target ZMP control (can shift weight to counterbalance inertial forces), and foot-planting location controls (allows ASIMO to reposition itself after the target ZMP is activated).

Another thing which makes ASIMO unique is the fluidness of ASIMO’s motions.  For example, as stated earlier, ASIMO has a smooth gait and is able to turn without stopping using the target ZMP control and foot-planting location controls.  When people turn, they shift their center of gravity around as well.  ASIMO uses a technology called “predictive movement control,” also known as Honda’s I-Walk (Intelligent Real-Time Flexible Walking Technology) to simulate this shift.  Using this technology, ASIMO is able to predict how far it has to shift its center of gravity, and how long to maintain the shift.  So, with every step ASIMO takes, the robot has to calculate inertia and predict how to shift its center of gravity by taking into account the length of its steps, its body position, its speed, and the direction it is stepping.  Going back to the degrees of freedom, ASIMO also has a degree of freedom in the hips which allows ASIMO to adjust its postures in midair.  Because of this, ASIMO can both walk and run, although at the very slow speed of 3.7 mph (6 km per hour).  ASIMO can also take into account counter centrifugal forces to maintain balance and anticipate turns as the robot runs.

In robotics, vision is a very tricky thing.  At its core, vision works in robotics by allowing the robot to detect different templates in the bot’s memory.  However, that means that the robot can only “see” what the robot remembers – the lighting has to be the same, the positions have to be the same, even the angle of shadows have to be the same.  Yet, a humanoid robot like ASIMO whose purpose is to be a helper needs to be able to navigate independently and react to its surroundings accordingly by sensing what the robot “sees.”  ASIMO’s “eyesight” consists of two basic video cameras located in ASIMO’s head for eyes.  ASIMO uses stereoscopic vision and a vision algorithm that lets the robot see, identify, and react to objects in its surroundings in real time without having to rely on the robot’s database of memory.  These cameras are able to perceive distance, motion, and objects, recognize programmed faces, and even understand gestures.  For example, ASIMO is able to “greet” familiar faces and recognizes an upright, open-faced palm as a gesture to stop.  The cameras can also send information back to ASIMO’s controller and allow the user to see what ASIMO sees.  Ultrasonic sensors allow ASIMO to react to the robot’s environment, and ASIMO can even “feel” things.  The six-axis force sensors in ASIMO’s wrist let ASIMO know how much force to exert when doing different actions, such as picking up an empty tray or pushing a cart filled with groceries.  ASIMO can also recognize infrared IC Communication Cards to receive and transmit information.  This allows ASIMO to interact with people better, as ASIMO will be able to recognize a person with an IC Card rather than having to recognize a pre-programmed version of that person’s face.

ASIMO is powered by a 51.8 volt lithium-ion battery that lasts for one hour on a single charge, takes three hours to charge, weighs 13 pounds (5.9 kg), and fits onto ASIMO as a “backpack.”  The robot also has a total of 34 servo motors (powerful motors with a rotating shaft that moves limbs and surfaces to a specific angle as specified by the controller) with position sensing technology, and can be controlled by a wireless controller, gestures, vocal commands, or a computer.

One of the greatest concerns of ASIMO appears to be the wariness of an overdependence on robotic technology.  However, ASIMO has the potential to be a companion, a helper, and even a life-saver.  For now at least, ASIMO is bringing the future to the present.


“Some have worried about robot rebellions, but with so many tort lawyers around to apply the brakes, the bigger questions is this: will humanoid machines enrich our social lives, or will they be a new kind of television, destroying our relationships with real humans?” – Fred Hapgood, Discover magazine


Posted in Current Engineering News