Vestibular dynamic inclinometer and measurement of inclination parameter

A human body displays a remarkable quality of maintaining both static and dynamic equilibrium for a rigid body in unstable equilibrium (modeled as an inverted pendulum). Biologically, the sensing of inclination is done by the human vestibular system. Here, a novel design of a sensor motivated by the human vestibular system is presented. The sensor, called the Vestibular Dynamic Inclinometer(VDI), measures the dynamic inclination parameters - inclination angle, angular velocity, angular acceleration and magnitude of the acceleration of surface of contact (e.g., gravity). The VDI uses two dual-axis linear MEMS accelerometers and one single axis MEMS gyroscope to measure the inclination parameters for a four degree-of-freedom robot. The concept of the Dynamic Equilibrium Axis (DEA) is introduced. The DEA is the axis along which the robot is at equilibrium. The direction of the DEA is parallel to the direction of the resultant acceleration of the surface of contact. Two control strategies - torque control and acceleration control are simulated to explain this concept. The DEA attempts to explain the reason why humans lean forward while accelerating (sprinting) and backward while decelerating (sudden stopping). The VDI is used to measure joint parameters - joint angle, angular velocities and angular accelerations, for links joined by revolute joint. Here, the VDI is a contactless sensor withe flexible point of application.;The VDI sensor is extended for inclination parameter measurement of five degree-of-freedom robot. The new sensor is called the planar Vestibular Dynamic Inclinometer (pVDI). The pVDI consists of four dual-axis linear MEMS accelerometers and one tri-axial MEMS gryoscope. The orientation of the linear accelerometers is different from the intuitive analogous VDI. This is due to the coupling in the kinematics. Similar to the VDI, the pVDI is used to measure joint parameters with links joined by universal hooke joint. The concept of the DEA is also extended.;The novelty of the VDI and the pVDI lies in the fact that the measurements are independent of drift or integration errors, acceleration of surface of contact (e.g., gravitational acceleration), independent of the dynamics of the robot, and require significantly less computational burden (closed form solution). The inclination angle obtained from the VDI and the pVDI is from the DEA. As the goal of balancing tasks is to bring the robot to equilibrium, the inclination parameters obtained from the VDI and the pVDI are suitable candidates for control applications. The application of the VDI and the pVDI is foreseen in gait analysis, industrial robotics, humanoid robotics, etc.