Humanoid handicapEven in their basic movement, humanoid – human-like – robots are at a decisive disadvantage compared to the specialists of their species: walking on two legs is far more complex than precisely controlled movement on wheels. Even humans need a good year before this seemingly trivial sequence of movements is mastered and the interplay between some 200 muscles, numerous complicated joints and various specialized regions of the brain materialies. On top of this is the fact that human biomechanics leave much to be desired in terms of energy efficiency. The unfavourable lever ratios of arms and legs require high power effort for relatively modest results.
Up to now, humanoid robots have therefore only been used as research objects, as toys or as both. Technical universities around the world have been holding robot football tournaments since the 1990s in which research, technical development and fun form a productive unit. There is a separate league here for humanoid robots. Moreover, there is a massive international community of robot enthusiasts who test their programming skills with self-made robots or robots made from prefabricated kits and, in doing so, also advance the knowledge about the possibilities of humanoid robots.
Power and intelligence packageThe Hovis series from Dongbu Robot has many supporters in this community. This is due not least of all to the so-called servos, which put the approximately 35 centimetre mechanical men into motion. The servos, which are also sold separately, are very popular among the ambitious hobbyists. A servo is a compact unit which – to continue the comparison to humans – sits as a muscle-tendon-nerve packet in the limbs. It converts battery power and control signals into independent movement. For small humanoid robots, Dongbu Robot developed the servo units of the HerkuleX series. They consist of a drive motor, a high-performance gearhead, an electronic feedback system (encoder) and a communication interface, all of which are accommodated together in a sturdy plastic housing.
The encoder ensures that the servo always exactly knows its current position. It also translates the control signal, for example, for the command "step forwards", and tells the motor how many revolutions are needed in order to perform the task. An optimally coordinated interaction between motor, software and control unit gives the robotic joint a certain degree of autonomy in the sequence of movements. With HerkuleX servo units, the machines are able to precisely control both simple as well as complex mobility patterns independently. Thanks to the sophisticated software in the encoder and its high-performance communication interface, the signals are transmitted quickly and exactly.
Compact efficiencyThe movement itself comes from the motor. Due to the – see above – unfavourable humanoid lever ratios, it must develop as much torque as possible with minimal dimensions. "Following a detailed comparison of the motors that are available on the market, Dongbu Robot selected the DC-micromotors of the 2224 SR and 2232 SR series from FAULHABER", explains D.S. Choi from Dongbu Robot. "The extreme compactness and high power generation of the motors were the decisive factors. In terms of dynamics and power density, they were the undisputed leaders. Furthermore, the name FAULHABER is synonymous with outstanding quality for robotics enthusiasts."
The DC-micromotors of the 2232 SR series achieve a continuous torque of 10 mNm with a motor diameter of just 22 millimetres. To accomplish this, they need very little power and begin their work even with a very low starting voltage. With an efficiency of up to 87 percent, they use the battery reserves with maximum efficiency. D.S. Choi: "This is extremely important for a long running time per charge. In addition, the linear characteristics of the motor simplify control for us."
With regard to their utility value, humanoid robots are still far from their stationary industrial colleagues and the rolling domestic servants. With advances in technology, their disadvantage could be transformed into a key advantage, however. Humans, too, were able to celebrate their evolutionary triumph on account of their comparatively unstable upright gait. From their non-specialisation grew virtually limitless possibilities which ultimately made them so successful. In any case, the robo-footballers have set the goal of being able to defeat the reigning human world champions by 2050.