Dynamic Gaits and Control in Flexible Body Quadruped Robot

Legged robots are highly attractive for military purposes such as carrying heavy loads on uneven terrain for long durations because of the higher mobility they give on rough terrain compared to wheeled vehicles/robots. Existing state-of-the-art quadruped robots developed by Boston Dynamics such as LittleDog and BigDog do not have flexible bodies. It can be easily seen that the agility of quadruped animals such as dogs, cats, and deer etc. depend to a large extent on their ability to flex their bodies. However, simulation study on step climbing in 3D terrain quadruped robot locomotion with flexible body has not been reported in literature. This paper aims to study the effect of body flexibility on stability and energy efficiency in walking mode, trot mode and running (bounding) mode on step climbing

Wireless signal acquisition and processing techniques for horse lameness detection and evaluation

Title from PDF of title page; abstract from research PDF (University of Missouri--Columbia, viewed on June 26, 2014).The Equine Lameness Locator(R) (ELL) is a newly developed system that provides a robust and objective method to detect and evaluate equine lameness. To achieve objective lameness evaluation, the system analyzes a horse's head and pelvis vertical movement signals during trotting. Two uniaxial accelerometers are placed on the horse's torso, one each on the horse's head and pelvis to record vertical accelerations. Vertical position signals are obtained by numerical double integration of the acceleration signals. However, these integrated position signals contain very large moving averages and require advance methods of signal processing for correction. In this thesis, a combination of the Hilbert Huang transform and a conjugate-pair decomposition method is proposed and tested against the current ELL's signal processing method, a sliding-window curve-fitting method. Numerical simulations and experimental results show that the proposed new method involves more intense computation but does not provide better results for lameness evaluation of horses. Hence, the original sliding-window curve-fitting method is recommended for future use. Clinical and experimental observations reveal that a horse's head and pelvis also rotate during trotting. These rotations may cause inaccurate measurements of the true vertical accelerations. Hence, this work also numerically and experimentally examines the influences of rotations on the measured vertical accelerations. Numerical techniques, unique experimental devices and setups, and an algorithm for correcting accelerometer outputs to obtain true vertical accelerations have been developed and experimentally validated

Energetics and Passive Dynamics of Quadruped Robot Planar Running Gaits

Quadruped robots find application in military for load carrying over uneven terrain, humanitarian de-mining, and search and rescue missions. The energy required for quadruped robot locomotion needs to be supplied from on-board energy source which can be either electrical batteries or fuels such as gasolene/diesel. The range and duration of missions very much depend on the amount of energy carried, which is highly limited. Hence, energy efficiency is of paramount importance in building quadruped robots. Study of energy efficiency in quadruped robots not only helps in efficient design of quadruped robots, but also helps understand the biomechanics of quadrupedal animals. This thesis focuses on the energy efficiency of planar running gaits and presents: (a) derivation of cost of transport expressions for trot and bounding gaits, (b) advantages of articulated torso over rigid torso for quadruped robot, (c) symmetry based control laws for passive dynamic bounding and design for inherent stability, and (d) effect of asymmetry in zero-energy bounding gaits