Grant: Research Tools and Instruments - Category 1 (<$150,000)

BACKGROUND: Stability is the primary requirement for bipedal walking. Two distinguished yet relevant stability criteria (Lyapunov's stability and transient stability) are often used, but suffer from two drawbacks: lacking a tool for Lyapunov's stability analysis and overly stringent for the transient stability. Such drawbacks cause high energy consumption of bipedal robots and prohibit their applications to monitoring human walking. It is paramount to develop tools for the stability analysis and less stringent transient stability criteria. RESEARCH PROGRAM: My research focuses on developing tools for Lyapunov's stability analysis and new transient stability criteria for energy-efficient bipedal robots. I proposed to develop a new stability criterion using a passive dynamic walker, a simple mechanism which can walk on a ramp remarkably similar to human gait without actuators. Such natural gait is stable and energy-efficient. Passive walkers have the advantages over humans for developing new transient stability criteria, in that they are simple in structure and have low measurement errors. On monitoring human walking, we developed a Telerehabilitation platform (TRP), a treadmill instrumented with low-cost sensors, for therapeutic exercise. Fall monitoring is crucial. Our newly developed methods for Lyapunov's stability analysis are challenged since the required states and their measurement quality (the noise and the length of the data) cannot be guaranteed due to the low-cost sensors used. We will extend our methods to the stability analysis with alternate states available from TRP, which are often short and noisy. Measurements of ground reactions especially the friction forces are crucial for both tasks. A Fully Instrumented Treadmill (FIT) is requested here. FIT provides data for the theoretical developments and the validation. It also provides guidelines of sensor selections for TRP. SIGNIFICANCE: The research can directly impact on the development of stable and energy-efficient bipedal walking robots and monitoring/prevention of falls of human walking. It advances the stability analysis of nonlinear engineering systems beyond bipedal locomotion systems.