The geometry, kinematics, and mechanical development of a symmetric and adjustable arm suspension mechanism for an actively stabilized single-legged hopping robot are presented. This mechanism is a key enabling design feature of a recently developed two-armed reaction wheel stabilized monopod, that is capable of conventional wheeled roving, continuous hopping, and self-uprighting. The mechanism is shown to behave essentially as a digressive-rate torsional spring placed between the two arms, in series with a weaker progressive rate torsional spring tied to the leg/central body. This makes it well-suited to recovering substantial energy from hopping motion, whilst presenting negligible resistance to antisymmetric motions used to maintain side-to-side stability. Furthermore, by storing energy purely in tension, the problem of buckling encountered with compression springs is avoided, and, the effective torsional spring constant may be varied by adjusting the spring pretension. Finally, the mechanism is self-latching near maximum deflection, allowing the vehicle to fold into a compact roving configuration, and enabling "running jumps" via the release of this gradually accumulated spring energy.

A versatile unmanned ground vehicle (UGV) should be able to traverse rough terrain while retaining a small form factor for navigating confined spaces. Such a (patent pending) vehicle, dubbed Switchblade, is developed in the present work via an effective combination of a novel transforming mechanical design, capable onboard electronics, and advanced feedback control algorithms. A single chassis holds the actuators, sensors, electronics, and battery. Shafts protruding from either side of this chassis connect to tread assemblies. Rotation of this shaft causes the treads to advance for translational movement; rotation about this shaft causes the entire tread assembly to rotate with respect to the chassis. Vehicle orientation is estimated via onboard filtering of optical encoders and MEMS accelerometers and gyros. In its horizontal configuration, Switchblade operates as a differential-drive treaded platform. In its various upright configurations, Switchblade operates as a mobile inverted pendulum, capable of surmounting obstacles, including stairs, that would otherwise be impassable by a vehicle of its size. Design-for-manufacturing (DFM) and design-for-assembly (DFA) techniques are employed to reduce cost, part count, complexity, and assembly time without sacrificing system capabilities. Results from a working prototype are discussed. The resulting platform is well suited for a variety of socially-relevant applications, including reconnaissance, mine exploration, and search & rescue.

A method for estimating the rotation center position (RCP) of a rigid body in the x-y plane using two offset accelerometers is presented. RCP estimation via inertial measurement is motivated by the related problems of detecting foot slippage of legged robots and detecting stair edges for treaded robots, for applications in which alternative methods such as discontinuity recognition, visual tracking, and/or tactile feedback are impractical. The RCP may be directly solved for as a function of the two offset tangential acceleration measurements, when the RCP is colinear with the two accelerometers, and when the common-mode tangential accelerations, due to linear acceleration and/or gravity, can be independently measured or estimated. Angular velocity estimates may be enhanced by combining calculated angular acceleration with gyroscope measurements, even when both the RCP and common-mode tangential accelerations cannot be independently measured. An input variance modulated variable cutoff low-pass filter is also proposed for RCP estimation in the absence of independent measurements, which is validated on a balance-beam inverted-pendulum apparatus.