Without on-board electronics: researchers control robotic arm with blue laser
The material of a soft robot arm reacts to laser light. Light patterns projected onto it move the robot arm at will.
Rice University scientist Elizabeth Blackert tests the technology to control the robotic arm.
(Image: Jeff Fitlow / Rice University)
A team of scientists at Rice University has developed a soft robotic arm that is moved remotely by laser beams. The arm does not require any wiring or control electronics. The soft material of the robotic arm reacts to laser light and can therefore perform any movement.
The robotic arm at Rice University is made of an azobenzene liquid crystal elastomer. It reacts to blue laser light, as the researchers write in the study "Spatiotemporally Controlled Soft Robotics with Optically Responsive Liquid Crystal Elastomers", which was published in Advanced Intelligent Systems. As soon as blue laser light falls on the robot arm, the material shrinks and bends in the direction of the laser light; in the dark, it expands again.
Laser light pattern controls robot arm
The material reacts immediately, allowing the arm to be controlled in real time using specific lighting sequences. Until now, conventional light-sensitive materials, which have to be irradiated with harmful ultraviolet light, for example, could not achieve this. They require too much time, sometimes up to several minutes, to reset the material. Real-time control is therefore not possible.
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In order to control the robot precisely, light patterns must be projected onto the robot arm. These light patterns are determined in advance by a neural network that is trained to predict them for certain arm movements.
The light patterns are generated by a spatial light modulator. It can be used to split a single laser beam into several beams and thus cover different parts of the robot arm. Depending on the position, duration and intensity of the irradiation, the individual areas of the robot arm bend more or less and thus perform the desired movements. Certain movements, even complex ones, can thus be initiated by an operator without the need for further control commands. The robot arm requires no electric motors, cabling or control electronics.
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The soft robot arm has no restrictions in its degrees of freedom, as the material can in principle be moved in all directions. This opens up a wide range of possible applications, for example in areas where sensitive objects need to be handled. The scientists at Rice University see their robot being used in medicine, for example.
However, the prototype of the robotic arm still has one limitation: it can only move in two dimensions. The researchers are already working on allowing it to perform three-dimensional movements as well.
(olb)
