Obtains Motion Capture Data at a Considerably Less Financial and Computational Cost
This inclinometer accurately measures, rather than estimates, inclination parameters: inclination angle, angular velocity, and angular acceleration of an object. The device is independent of drift errors due to integration errors and is valid for large angle measurements without requirement of any mathematical approximation. Many industries use different types of inclinometers to dynamically measure inclination to study human movement, to navigate, and to measure joint angles. For example motion-capture systems are used to analyze gait and sports motion, to monitor daily activities, evaluate falls, balance prosthesis, conduct remote surveillance on patients, and to perform joint-angle measurement of manipulators. The new device determines inclination in static and dynamic environments. Traditional MEMS inertial sensors, built into a wide range of consumer electronics such as mobile phones and video-game controllers, can determine inclination only in a static case. Dynamic inclination sensors, commonly referred to as Inertial Measurement Units (IMUs), estimate inclination, are costly, are prone to drift (integration) errors, and estimate relative change in position. The new device developed by University of Florida researchers calculates the inclination in the dynamic environment without these shortcomings. The improved inclinometer, based on the human vestibular system, mimics the balance center of the ear.
Application
An inclinometer for motion-capture products including but not limited to sports and rehabilitation, patient evaluation and surveillance, measurement of joint angles of manipulators, measurement in varying gravity conditions such as in space and in moving vehicles, and humanoids and intelligent robots
Advantages
- Measurements are independent of integration drift errors, making inclination measurements valid for large angles
- Independent of change in gravity magnitude, allowing use in varying gravity conditions such as space and moving vehicles
- Inexpensive, allowing incorporation of multiple MEMS inertial sensors
- Computationally cheaper than estimation algorithms, increasing profit margins
- Incorporates a non-contact, flexible sensor, enabling joint angle measurements
Technology
Dynamic inclinometers measure the inclination angle, angular velocity, and angular acceleration of an object relative to the direction of an equilibrium axis (e.g. gravity). What is special about this hardware and algorithm combination is that the inclination parameters are obtained from instantaneous measurements and are not dependent on previous measurements, thus eliminating the possibility of integration errors. Unlike traditional technologies, the rate of change of inclination is not obtained by integration of angular velocity (gyroscope signal), rather by mathematical manipulation of measurements from the accelerometers. The design mimics symmetry of the placement of the vestibular systems (ears). Each vestibular organ is assumed to be analogous to a MEMS accelerometer-gyroscope combination. For a planar case, such as walking along a line, using two dual-axis accelerometers and a single gyroscope, this technology precisely measures the inclination parameters. For the case of spatial movement, such as playing in a field, four dual-axis accelerometers and one triaxial gyroscope measure inclination parameters. The non-contact sensors allow flexible point of application measurement, are inexpensive, and require significantly less computation burden.
Brochure
