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Life-sized Humanoid Robot Capable of Getting Up and Lying Down
For the first time in the world, a life-sized humanoid robot with the ability to get up and lie down on its own has been successfully built by the collaboration of Intelligent Systems Research Institute, AIST and Kawada Industries Inc. These two movements were realized by the deft combination of hardware and software: Kawada Industries Inc. successfully designed the hardware "with a mechanism similar to that of a human body which does not carry a backpack and is equipped with flexible waist joints and high-powered arms", whilst AIST developed the software which "regulates the systemic movement by controlling its center of gravity to enable the shift of support. This achievement has marked an important step toward the practical use of humanoid robot workers.
Characteristics of the Humanoid Robot HRP-2 Prototype
This robot with the ability of these movements is the HRP-2 prototype (HRP-2P), and is called P-chan for short nick after the capital letter of "prototype" among the researchers engaged in this project. P-chan is 154cm tall; it weighs 58kg and its height for weight ratio is very similar to that of human. It is much more light-weighted compared to the previous humanoid robots. In order to realize the "standing-up" movement and "falling or tipping-over", it has the following characteristics:
1. high density electronics installation package to eliminate a bulky backpack which can be a hindrance of getting-up movement,
2. larger moving range of center of gravity as well as the distance of arm's reach thanks to the flexible hip-joint axes that allow a great deal of freedom of bending movement, and
3. increased power of the arms to the level of the legs, to have them enabled to support the upper body.
Weakness Resolved through Getting-up Movement
For the practical application of humanoid robots, one of the most significant issues has been the fact that humanoid robots are relatively susceptible to falling over. When a humanoid robot stands on two legs, what supports the body weight is an extremely restricted area of the bottoms of its feet whereas the gravity center is located at relatively high position, that is around the waist. Therefore, a biped robot is considerably unstable compared to the wheel-type robot or the robots with four or six legs.
In order to overcome this weakness, a great deal of effort has been made to create a robust gait control system and improve its adaptability, focusing on "prevention from falling" of the robot. However, so long as it functions in an environment with unexpected factors arising from co-existence with human beings, it is almost impossible to liberate the robot from possibility of falling. Consequently, a different approach to the weakness has been adopted: developing a robot which has an ability to get up on its own from fallen positions. Based on this idea, the weakness can be resolved by coordination of the following three motor controls.
1. Prevention from falling or tipping-over as far as possible (stabilization),
2. Taking a passive attitude in order to protect itself and surrounding objects from damage when it falls (falling or tipping-over control), and
3. Raising oneself from the ground to a standing position (recovery of the position).
The robot with an ability of getting up on its own to continue the
work will make a great contribution to the realization of humanoid
robot workers. The achievement of this time was produced by adding
the ability of recovering the position as above 3 to the long pursued
research goal: prevention of falling.
The software controls the shift of the stance of the robot body by regulating the position of the center of gravity. Firstly, the movements of getting-up and lying-down were resolved into their component elements in accordance with the stance as they determine the way of controlling the gravity center. The results are shown in the figure as below. The smooth shift between stances were obtained by allocating a suitable position of the center of gravity to each of the component movements in each of the ten different stances.
Further Progress of the Research & Development of the Humanoid Robot
The current robot can raise itself only when it lies down (either facing up or down) on its own. The technology of falling control will be integrated so that the robot can get up in case it falls accidentally.
Furthermore, HRP-2, considered to be the final version at this stage, will be completed by the end of 2002 and it is considered to make it commercially available for research and development purposes. In addition, the internal API (Application Programming Interface) of HRP-2 will be open to the public, allowing the users to develop software.
A venture software company established in October 2002 will take charge of the operation and maintenance of the current control software including the position recovery function. New software development will also be continued.
Humanoid Worker Robot
So far industrial robots have been working in the environment suitable for them such as factories. Even though Japan is the world's biggest market for industrial robots, the market size has remained flat at approximately 500 to 600 billion yen since the 1980's. The main reason for this is that the variety of tasks which can be handled by a robot has been limited, and it is essential to develop a robot which can work alongside the humans in a less-controlled environment. For human-interactive operations, humanoid robots are the best suited to such purposes. A robot which has a shape very similar to that of human beings is capable of operating in the environment
Since Honda Motor Co., Ltd. introduced the humanoid robot P2 in 1996, a number of humanoid robots have been developed, and the humanoid robot has entered into a new era of technical epoch. Honda Motor Co., Ltd. released a robot called ASIMO and Sony Corporation unveiled its SDR-4X. ASIMO can be even rented for events. However, the applications of these robots has been specialized in the area of entertainment, and they are not intended for work.
This research is a part of a five-year program launched by Ministry of Economy, Trade and Industry in 1998, "Humanoid Robotics Projects (HRP)" under the project leader, Mr. Hirochika Inoue, Professor of Tokyo University. The project aims at presenting the possibility of realization of humanoid worker robot through the researches on application examples of humanoid robots.