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Energy absorbing materials, like foams used in protective equipment, are able to undergo large deformations under low stresses, reducing the incoming stress wave below an injury or damage threshold. They are typically effective in absorbing energy through plastic deformation or fragmentation. However, existing solutions are passive, only effective against specific threats and they are usually damaged after use. Here, we overcome these limitations designing energy absorbing materials that use architected lattices filled with granular particles. We use architected lattices to take advantage of controlled bending and buckling of members to enhance energy absorption. We actively control the negative pressure level within the lattices, to tune the jamming phase transition of the granular particles, inducing controllable energy absorption and recoverable deformations. Our system shows tunable stiffness and yield strength by over an order of magnitude, and reduces the transmitted impact stress at different levels by up to 40% compared to the passive lattice. The demonstrated adaptive energy absorbing system sees wide potential applications from personal protective equipment, vehicle safety systems to aerospace structures.Architected lattices are materials whose properties arise from the selection of both their constitutive materials and the geometry of their micro-and meso-structure [1-5]. Architected materials have been proposed as new energy absorbing solutions with recoverable deformation, for example, taking advantage of mechanical instabilities in their underlying structure [6][7][8]. Although reusable, these solutions are intrinsically passive, with properties fixed once fabricated, and effective in mitigating impact loads under predefined velocities or energies. Most practical applications, however, require adaptive structures whose mechanical properties can be tuned to absorb or dissipate varying amounts of energy, in response to different impact conditions. Solutions to tune the mechanical properties of materials and structures [9,10] include the use of hydrogels that respond to temperature, pH, light and water content [11,12]; shape memory alloys and polymers (SMAs and SMPs) [13,14]; liquid crystal elastomers (LCEs) that respond to temperature and light [15,16]; and magnetorheological (MR) and electroactive polymers (EAPs) [17][18][19]. However, these materials either are mechanically too soft for engineering applications (hydrogels), require large temperature changes (LCEs), need re-programming at high

This paper discusses hardware and software improvements to the RoboSimian system leading up to and during the 2015 DARPA Robotics Challenge (DRC) Finals. Team RoboSimian achieved a 5th place finish by achieving 7 points in 47:59 min. We present an architecture that was structured to be adaptable at the lowest level and repeatable at the highest level. The low‐level adaptability was achieved by leveraging tactile measurements from force torque sensors in the wrist coupled with whole‐body motion primitives. We use the term “behaviors” to conceptualize this low‐level adaptability. Each behavior is a contact‐triggered state machine that enables execution of short‐order manipulation and mobility tasks autonomously. At a high level, we focused on a teach‐and‐repeat style of development by storing executed behaviors and navigation poses in an object/task frame for recall later. This enabled us to perform tasks with high repeatability on competition day while being robust to task differences from practice to execution.

The use of bulk metallic glasses (BMGs) as the flexspline in strain wave gears (SWGs), also known as harmonic drives, is presented. SWGs are unique, ultra-precision gearboxes that function through the elastic flexing of a thin-walled cup, called a flexspline. The current research demonstrates that BMGs can be cast at extremely low cost relative to machining and can be implemented into SWGs as an alternative to steel. This approach may significantly reduce the cost of SWGs, enabling lower-cost robotics. The attractive properties of BMGs, such as hardness, elastic limit and yield strength, may also be suitable for extreme environment applications in spacecraft.

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