Energy storage scheme for modulating the power before jumping at the SALTO robot. Illustration: University of California, Berkeley

Engineers from the University of California at Berkeley designed a 100-gram robot SALTO (SAtatorial Locomotion on Terrain Obstacles), which overcomes multi-meter obstacles, quickly jumping one meter high. The main idea is that the power developed during the jump exceeds the power of the motors of the robot. The idea of ​​accumulation and release of energy (modulation of power) was borrowed from the animal world, namely, from the Senegalese galago, a small African animal with large eyes.

Following the example of the Senegalese Galago, the SALTO robot makes a series of consecutive jumps, including starting from vertical walls, like in parkour. Perhaps these machines will be used in the army and the Ministry of Emergency Situations.

Constructing a SALTO robot, scientists studied animals with maximum vertical jumping ability. In nature, there are only a few mammals that can jump to a height of more than two meters from a state of rest, with the possibility of an immediate repetition of such a jump. The champion among these animals is the Senegalese galago ( Galago senegalensis ).
')

Senegalese Galago (Galago senegalensis)

The animal is adapted to nightlife. The body length of the Senegalese galago is from 13 to 21 cm, the length of the tail is from 20 to 30 cm. The weight is approximately 200 to 300 g.

Power modulation

The Senegalese Galago is able to overcome vertical obstacles up to five meters using a unique jumping system, known in the literature on biomechanics as power modulation or power amplification. This term means that the instantaneous power delivered by the animal's muscle-tendon complex exceeds the maximum strength of its muscles . Such "spring" complexes are found in various species, including chameleons, salamanders, sea needles, some rotapods and other animals.

In the process of modulating the power of the muscle is transferred to the accumulation of energy in a series of elastic structures connected in series or in parallel. Then this energy is released at once, so that the total return exceeds the strength of the muscles alone. In a robot, springs or elastic bands are used to accumulate potential energy.

The location of these elastic structures determines the order of energy input from the drives and the method of its transformation from potential to kinetic. Engineers from the University of California at Berkeley set the task to develop an elastic drive with a series connection , which will show the maximum vertical jumping ability.

Vertical jumping ability

By vertical jumping is meant the quotient of the height of the jump and the amount of time to prepare the jump and the flight time to the highest point. That is, the vertical jumping is equal to

h / (t ₁ + t ₂ )

Scientists have measured the parameter of vertical jumping in various robots and living organisms. The measurement result is shown in the graphs.



On the left graph, it is noted what height the drives of different designs with different vertical jumping ability can overcome in 4 seconds. For example, the parallel-elastic robot EPFL Jumper for 4 seconds jumps once to a height of 1.3 meters, which corresponds to an indicator of vertical jumping of just 0.34 m / s. In Minitaur, this indicator is 1.1 m / s. Finally, the SALTO robot represented in this research paper (marked in red) has a vertical jumping capacity of 1.7 m / s. Each jump per meter takes only 0.58 s. This means that in four seconds such a robot can drop almost seven meters. For comparison, the lively Senegalese galago has a vertical jumping capacity of 2.2 m / s.

On the right graph it is clear that SALTO has an almost perfect combination of maximum height and frequency of jumps. It is due to such an ideal combination that he demonstrates a record figure of vertical jumping among all robots in the world.

The previous record holder for this indicator was Minitaur , a much larger and seemingly rather clumsy robot (jumping 48 cm in 0.43 s). The absolute height of jumps record holds Israeli robot TAUB , designed on the model of the locust. He has a jump height of 3.2 m.


The mechanics of the 26-centimeter one-legged SALTO can be tried in other robots, including robots with a large number of legs, which also use an elastic drive with a series connection . These are robots like StarlETH , ANYmal and ATRIAS .

And imagine that powerful "muscular-tendinous" complexes like that of SALTO will be put on a humanoid robot like Atlas ? With such an opponent does not want to face in a dark alley.


Atlas Robot from Boston Dynamics

The scientific work was published on December 6, 2016 in the first issue of the new journal Science Robotics (doi: 10.1126 / scirobotics.aag2048). The study was funded by the US National Science Foundation and a division of the US Army US Research Laboratory as part of the Micro Autonomous Systems and Technology Collaborative Technology Alliance research initiative.