locustThe ability for insects to move limbs without muscles may pave the way for improved control of robotic and prosthetic limbs, according a news release from the University of Leicester. Neurobiologists are currently working to outline how insects control their movements using a close interplay of neuronal control and what Tom Matheson, reader in Neurobiology at the University of Leicester calls “clever biomechanical tricks.”

The study, which appears in the journal Current Biology suggests that the structure of some insect leg joints causes the legs to move even in the absence of muscles. This allows the “passive joint forces” to return the limb back towards the preferred resting position.

Researchers note they were surprised to find that these passive forces, not just highly specialized rapid movements needed for powerful jumps or kicks, contribute to almost all movements by the limbs that were studied.

After studying locust hind legs, Matheson notes that, “when the muscles were removed, the tibia naturally flexed back towards a midpoint, and we hypothesized that these passive return movements might be counterbalancing the strong extensor muscle.”

Jan M. Ache, Masters student, University of Cologne, who worked in Matheson’s lab adds that researchers tested this idea by investigating literature and examining other legs where the extensor and flexor muscles are more closely balanced in size or strength, or where the flexor is stronger than the extensor.

“We found that the passive joint forces really do counterbalance the stronger of the flexor or extensor muscle in the animals and legs we looked at,” Ache says.

The release states that the use of balanced passive forces may provide engineers with new ways to improve the control of prosthetic and robotic limbs.

Matheson rearticulates this hope adding that the team’s work with locusts and grasshoppers may, “spur a new understanding of how limbs work and can be controlled, by not just insects, but by other animals, people, and even by robots.”

Source: Biotechnology and Biological Sciences Research Council (BBSRC)