Exobuddy - A Non-Anthropomorphic Quasi-Passive Exoskeleton for Load Carrying Assistance

The load that is carried in military backpacks has drastically increased over the years. Besides energy expenditure, load carriage increases joint loading which has been associated with an increased risk on injuries, discomfort, and reduced task performance. To support soldiers during load carrying, exoskeletons have been proposed. The use of exoskeletons for load carrying is limited since current active exoskeletons have the disadvantage that their power requirements make them unsuitable for long use and (quasi-)passive exoskeletons have mainly focused on metabolic cost. In this paper we present the Exobuddy exoskeleton. The Exobuddy transfers a part of the load directly to the ground. The Exobuddy mechanism is quasi-passive and thereby eliminates the need for large energy sources associated with active exoskeletons. The Exobuddy was evaluated in indoor and outdoor conditions, each completed by four subjects. Exobuddy unloaded the subjects by transferring on average approximately 30% (130 N) of the load to the ground with a maximum of 53% right after heel strike. The energy drawn from the human body to power the quasi-passive mechanism led only to a small, non-significant, increase in energy expenditure. Although not significant, carrying loads with Exobuddy was perceived less exerted and more comfortable compared to carrying loads with the current backpack.