Humans instinctively adopt the gait that requires the least amount of energy given the walking conditions. Without realizing it, we are constantly tweaking our pace, stride length and foot lift. But could we consciously play with these parameters in order to influence our energy expenditure?

Researchers at EPFL's Biorobotics Laboratory studied eight gait parameters in order to come up with a very sophisticated software program that uses an avatar to predict how much energy people use when they walk depending on their walking style. This research has been published in Scientific Reports. Salman Faraji, the co-lead author, devoted an entire section of his thesis to this topic.

The avatar - a torso equipped with two legs with feet - can be freely configured. Users start by entering their height and weight and can then set the walking speed, distance between their feet (stride length and stride width), and foot lift, along with the incline of both the torso and the ground. They can also add mass and simulate the effect of being pushed or pulled at different parts of the body. The number of calories burned and the energy consumption are displayed in real time whenever the parameters are modified.

Making custom exoskeletons

This pioneering software drew on a number of experiments appearing in recent literature, and it offers a huge number of potential applications - especially in the medical realm. "The software could be used to select the best design for an exoskeleton or a custom prosthetic, in order to reduce the user's effort. With a wearable exoskeleton, for example, we could optimize the location of the battery and actuators, or determine the ideal walking pattern for the user's preferred speed," says Amy Wu, the study's other co-lead author. The software could even determine where a backpack should be worn in order to minimize energy expenditure. "If, on the other hand, your goal is to burn calories, the software could be used to find a series of movements with a high metabolic cost."

Designed for humanoid robots

The software was created in a robotics lab and was initially intended to study the mechanics of human gait for use in humanoid robots. "The way humans walk is extremely complex. The level of control required is a huge challenge for humanoid robots, which often don't get it quite right," says Faraji. "We have a long way to go before we really understand all the parameters that go into human, animal and robot locomotion."

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An application can be downloaded in order to try out the simulator here: https:/ / biorob. epfl. ch/ research/ humanoid/ walkman

Publication in Scientific Reports : A simple model of mechanical effects to estimate metabolic cost of human walking