by David Bradley
Scientists at Johns Hopkins University have developed a spherical motor
operated by magnets and software.
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A spherical motor that can rotate in any direction has been devised by US scientists to help bring flexibility and 3D movement to robot arms. The device could even be used as a computer mouse that pulls your hand, rather than the other way round, for interactive games and programs.
Magnetic attraction
"A conventional motor turns on an axis, moving in one direction," says mechanical engineer Gregory Chirikjian of Johns Hopkins University in Baltimore, Maryland. "What we've developed is a new type of spherical motor. Basically, there's a ball inside, and we can rotate it in any direction we want."
Magnetic forces and complex computer software make the device work. Inside the ball are 80 permanent magnets sitting in a hollow sphere. This sphere then sits in a 'saddle' of 16 circular electromagnets connected to the computer. When the engineers activate two or more of these electromagnets, there is an attractive magnetic force between the permanent magnets inside the sphere and the saddle, which pulls the ball into a new position.
Moving a robot's elbow
This is not the first attempt at a spherical motor but is the most advanced, the team says, and allows for a much greater degree of movement. The inventors say the spherical motor could act like a human shoulder joint by replacing the six standard electric motors needed to manipulate the 'elbow' of a robotic arm. This would allow the robot arm to move easily in three dimensions, as well as being more accurate because there are fewer moving parts.
Robotics: finding out more
http://caesar.me.jhu.edu/
Home page for Gregory Chirikjian and his robotics lab
http://telerobot.mech.uwa.edu.au/
Have a go at controlling a robot arm online
http://www.epub.org.br/cm/n09/historia/turtles_i.htm
Investigate the history of robots and cybernetics
Activity
How do motors work?
Conventional motors work by converting electrical energy into rotational movement.
- Find out how they do this.
- What forces are involved in the movement?
- Think about applications, other than making robots more human-like in their movements, in which a spherical motor could be used.
The idea of a computer mouse that can pull your hand around seems strange: think about whether there will be a time when you might get into a physical argument with your PC!
