Deltanine

Bleex 1, an experimental exoskeleton, lets a person carry a 70-lb load, along with the 100-lb Bleex 1 itself, but feel as if he is carrying a 5-lb load.

Bleex 1 consists of a pair of hydraulically powered leg braces, more than 40 electronic sensors, a control computer, and an internal-combustion engine providing power from an attached backpack. The plastic and carbon-fiber braces are affixed rigidly to the soldier through a customized pair of standard Army boots, with more compliant and giving connections at the chest and waist. These looser connections prevent blisters and abrasions.

The 2-hp engine turns a pump to pressurize the hydraulic system with 1,000-psi fluid. Hydraulics power the actuators, giving the exoskeleton its muscles and letting it move. The engine also turns a generator for electricity. The device carries about a quart of gas, enough for 15 min of high-powered walking. After experimenting with a number of fuels, including concentrated hydrogen peroxide, Kazerooni (lead engineer) decided on using gasoline based on its power density. It also lets the device be refueled in the field. If Darpa has its way, however, the exoskeleton delivered to the Army will probably use JP-4, the common battlefield fuel for tanks, humvees, and other armored vehicles.

Key to controlling Bleex 1 is the lack of operator controls. Instead, Berkeley researchers clinically analyzed the human gait and programmed the robotic legs to follow that pattern. The wearer simply moves his limbs, and the suit detects that movement and powers the suit to follow. The backpack load is almost entirely supported by Bleex. But because the device is so sensitive to inputs, it is almost unstable, says Kazerooni. The operator is needed to provide balance.