Researchers from ETH Zurich and the Max Planck Institute for Intelligent Systems have developed an animal-inspired robotic leg with artificial muscles as part of a research partnership. The publication has been published in the journal Nature Communications.
Zurich, September 09th, 2024 – Research into the development of robots has been going on for over 70 years. What they have all had in common so far is that motors had to be used, which meant that their scope was limited. In some cases, they lack the mobility and adaptability of living beings. Researchers from ETH Zurich and the Max Planck Institute for Intelligent Systems (MPI-IS) have now been able to develop a muscle from an electrohydraulic actuator as part of a research partnership called the Max Planck ETH Centre for Learning Systems.
Electrically charged like a balloon
As in humans and animals, an extensor and a flexor muscle ensure that the robotic leg can move in both directions. These electro-hydraulic actuators, which the researchers call HASELs, are attached to the skeleton via tendons.
The actuators are plastic bags filled with oil. Around half of the bag is coated on both sides with a black electrode, i.e. a conductive material. Buchner explains: ‘As soon as we apply voltage to the electrodes, they attract each other due to static electricity. If I rub a balloon against my head, my hair sticks to the balloon due to the same static electricity’. When you increase the voltage, the electrodes pull closer together and push the oil in the bag to one side, making the bag shorter overall.
Pairs of these actuators, which are attached to a skeleton, lead to the same paired muscle movements as in living beings: When one muscle shortens, its counterpart lengthens. The researchers use a computer code that communicates with high-voltage amplifiers to control which actuators should contract and which should lengthen.
Agile locomotion over uneven terrain
The researchers were able to show that the robot leg is highly adaptable. To be able to jump, it is necessary to lift its own body weight explosively. The elasticity of this developed muscle is able to adapt agilely to the respective terrain. ‘This is no different for living beings. If we can’t bend our knees, for example, we have great difficulty walking on an uneven surface,’ says Katzschmann. ‘Just think of the step from the pavement onto the road.’
Katzschmann continues: ‘If we combine the technology of the robotic leg to create a four-legged robot or a humanoid robot with two legs, we will one day be able to use it as a rescue robot as soon as it is battery-powered.’
Originalveröffentlichung:
Buchner TJK, Fukushima T, Kazemipour A, Gravert SD, Prairie M, Romanescu P, Arm P, Zhang Y, Wang X, Zhang SL, Walter J, Keplinger C, Katzschmann RK: Electrohydraulic musculoskeletal robotic leg for agile, adaptive, yet energy-efficient locomotion. Nature Communications, 9. September 2024, doi: 10.1038/s41467-024-51568-3
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