Exoskeletons for Human Performance Augmentation 33.6 Lower-Extremity Exoskeleton 781 on his/her back with minimal effort over any type of surpass typical human limitations.BLEEX has nu- terrain.BLEEX allows the pilot to comfortably squat,merous potential applications;it can provide soldiers, bend,swing from side to side,twist,and walk on as- disaster relief workers,wildfire fighters,and other emer- cending and descending slopes,while also offering the gency personnel with the ability to carry heavy loads ability to step over and under obstructions while carry- such as food,rescue equipment,first-aid supplies,com- ing equipment and supplies.Because the pilot can carry munications gear,and weaponry,without the strain significant loads for extended periods of time without typically associated with demanding labor.Unlike un- reducing his/her agility,physical effectiveness increases realistic fantasy-type concepts fueled by movie-makers significantly with the aid of this class of lower-extremity and science-fiction writers,the lower-extremity exoskel- exoskeletons.In order to address issues of field robust-eton conceived at Berkeley is a practical,intelligent, ness and reliability,BLEEX is designed such that,in load-carrying robotic device.It is our vision that BLEEX the case of power loss (e.g.,from fuel exhaustion),the will provide a versatile and realizable transport platform exoskeleton legs can be easily removed and the re-for mission-critical equipment. mainder of the device can be carried like a standard The effectiveness of the lower-extremity exoskeleton backpack. stems from the combined benefit of the human intellect BLEEX was first unveiled in 2004,at UC Berke-provided by the pilot and the strength advantage of- ley's Human Engineering and Robotics Laboratory.In fered by the exoskeleton;in other words,the human this initial model,BLEEX offered a carrying capacity provides an intelligent control system for the exoskel- of 34kg (75Ibs),with weight in excess of that al-eton while the exoskeleton actuators provide most of lowance being supported by the pilot.BLEEX's unique the strength necessary for walking.The control algo- design offers an ergonomic,highly maneuverable,me- rithm ensures that the exoskeleton moves in concert chanically robust,lightweight,and durable outfit to with the pilot with minimal interaction force between the two.The control scheme needs no direct measure- ments from the pilot or the human-machine interface (e.g.,no force sensors between the two);instead,the controller estimates,based on measurements from the exoskeleton only,how to move so that the pilot feels very little force.This control scheme,which has never before been applied to any robotic system,is an effective method of generating locomotion when the contact loca- tion between the pilot and the exoskeleton is unknown and unpredictable (i.e.,the exoskeleton and the pilot are in contact in variety of places).This control method differs from compliance control methods [33.27,28]em- ployed for upper-extremity exoskeletons [33.17,21]and haptic systems [33.18,19]because it requires no force sensor between the wearer and the exoskeleton. The basic principle for the control of an exoskel- eton rests on the notion that the exoskeleton needs to shadow the wearer's voluntary and involuntary move- ments quickly,and without delay.This requires a high level of sensitivity in response to all forces and torques on the exoskeleton,particularly the forces imposed by Fig.33.10 Berkeley lower-extremity exoskeleton(BLEEX) the pilot.Addressing this need involves a direct conflict and pilot Ryan Steger.1:The load occupies the upper por-with control science's goal of minimizing system sen- tion of the backpack and around the power unit;2:rigid sitivity in the design of a closed-loop feedback system. connection of the BLEEX spine to the pilot's vest;3:the If fitted with a low sensitivity,the exoskeleton would Part D power unit and central computer occupies the lower portion not move in concert with its wearer.One should realize, of the backpack;4:semirigid vest connecting BLEEX to the however,that maximizing system sensitivity to external 出 pilot:5:one of the hydraulic actuators:6:rigid connection forces and torques leads to a loss of robustness in the of the BLEEX feet to the pilot's boots system.Exoskeletons for Human Performance Augmentation 33.6 Lower-Extremity Exoskeleton 781 on his/her back with minimal effort over any type of terrain. BLEEX allows the pilot to comfortably squat, bend, swing from side to side, twist, and walk on as￾cending and descending slopes, while also offering the ability to step over and under obstructions while carry￾ing equipment and supplies. Because the pilot can carry significant loads for extended periods of time without reducing his/her agility, physical effectiveness increases significantly with the aid of this class of lower-extremity exoskeletons. In order to address issues of field robust￾ness and reliability, BLEEX is designed such that, in the case of power loss (e.g., from fuel exhaustion), the exoskeleton legs can be easily removed and the re￾mainder of the device can be carried like a standard backpack. BLEEX was first unveiled in 2004, at UC Berke￾ley’s Human Engineering and Robotics Laboratory. In this initial model, BLEEX offered a carrying capacity of 34 kg (75 lbs), with weight in excess of that al￾lowance being supported by the pilot. BLEEX’s unique design offers an ergonomic, highly maneuverable, me￾chanically robust, lightweight, and durable outfit to 1 2 3 4 5 6 Fig. 33.10 Berkeley lower-extremity exoskeleton (BLEEX) and pilot Ryan Steger. 1: The load occupies the upper por￾tion of the backpack and around the power unit; 2: rigid connection of the BLEEX spine to the pilot’s vest; 3: the power unit and central computer occupies the lower portion of the backpack; 4: semirigid vest connecting BLEEX to the pilot; 5: one of the hydraulic actuators; 6: rigid connection of the BLEEX feet to the pilot’s boots surpass typical human limitations. BLEEX has nu￾merous potential applications; it can provide soldiers, disaster relief workers, wildfire fighters, and other emer￾gency personnel with the ability to carry heavy loads such as food, rescue equipment, first-aid supplies, com￾munications gear, and weaponry, without the strain typically associated with demanding labor. Unlike un￾realistic fantasy-type concepts fueled by movie-makers and science-fiction writers, the lower-extremity exoskel￾eton conceived at Berkeley is a practical, intelligent, load-carrying robotic device. It is our vision that BLEEX will provide a versatile and realizable transport platform for mission-critical equipment. The effectiveness of the lower-extremity exoskeleton stems from the combined benefit of the human intellect provided by the pilot and the strength advantage of￾fered by the exoskeleton; in other words, the human provides an intelligent control system for the exoskel￾eton while the exoskeleton actuators provide most of the strength necessary for walking. The control algo￾rithm ensures that the exoskeleton moves in concert with the pilot with minimal interaction force between the two. The control scheme needs no direct measure￾ments from the pilot or the human–machine interface (e.g., no force sensors between the two); instead, the controller estimates, based on measurements from the exoskeleton only, how to move so that the pilot feels very little force. This control scheme, which has never before been applied to any robotic system, is an effective method of generating locomotion when the contact loca￾tion between the pilot and the exoskeleton is unknown and unpredictable (i. e., the exoskeleton and the pilot are in contact in variety of places). This control method differs from compliance control methods [33.27,28] em￾ployed for upper-extremity exoskeletons [33.17,21] and haptic systems [33.18, 19] because it requires no force sensor between the wearer and the exoskeleton. The basic principle for the control of an exoskel￾eton rests on the notion that the exoskeleton needs to shadow the wearer’s voluntary and involuntary move￾ments quickly, and without delay. This requires a high level of sensitivity in response to all forces and torques on the exoskeleton, particularly the forces imposed by the pilot. Addressing this need involves a direct conflict with control science’s goal of minimizing system sen￾sitivity in the design of a closed-loop feedback system. If fitted with a low sensitivity, the exoskeleton would not move in concert with its wearer. One should realize, however, that maximizing system sensitivity to external forces and torques leads to a loss of robustness in the system. Part D 33.6