In some science fiction movies, evil robots refuse to die, no matter how hard people fight back.
Now science fiction has become science fact. For the first time, scientists have made a robot that can take a beating(挨打) and keep on going. Scientists from Cornell University made the robot, which looks like a spider with four legs.
Until now, even the most advanced(先进的) robot was almost certain to break down when it was damaged(毁坏). That is because its computer inside simply doesn't know how to make the machine work after its shape has changed.
To deal with this problem, the scientists put eight motors(发动机) and two sensors(传感器) that read how the machine is working. They all give signals to the machine's software. Using this information, the computer can then figure out the machine's shape at any moment.
The new technology is a big advance in robot-making, scientists say, and it's far from scary. It may someday help scientists create better artificial(假的) arms and legs and give new freedom to people who lose them. It might also help scientists understand how people and animals figure out their own sense of place in space.
“It has been difficult to design robots that can work well when the environment changes or when it's damaged,” says Olaf Sporns of Indiana University in US. “With this work, we are nearer to solving this problem.”
的木板B放在水平地面上，质量为
的木箱A放在木板B上。一根轻绳一端拴在木箱上，另一端拴在天花板上，轻绳与水平方向的夹角为
。已知木箱A与木板B之间的动摩擦因数
。现用水平方向大小为200N的力F将木板B从木箱A下面匀速抽出（
，重力加速度g取10m/s2），则木板B与地面之间的动摩擦因数
大小为（ ）