Determination of the orientation of an object within a 3D space. Implementation and example applications

The article presents a design of a measurement system implementing algorithms for determination of the orientation of objects within three-dimensional space using am integrated triaxial MEMS system, magnetometer, and Madgwick’s AHRS sensor fusion algorithm. Also included in the proposed implementation are the algorithms for calibration of sensors. Estimated orientation of the object of interest is provided using Euler’s angles or quaternions The system consists of a data acquisition system and software to visualize the acquired data. The main components of the acquisition system include a microcontroller featuring ARM Cortex M4 processor core and integrated 9DOF module consisting of an accelerometer, gyroscope, and magnetometer. The measurement system is capable of communicating with other devices via a Bluetooth interface. The measurements of the monitored values read by 9DOF sensors may be collected at sampling frequencies of up to 100Hz. Options to save data to SD cards and to maintain power supply from a battery are also available. The proposed solution is characterized by low construction costs, small dimensions, and ease of implementation in all types of systems. It can be used for example in mapping the movement of limbs (spatial orientation of the foot, detection of gait cycle phases, assessment of motor activity), as a support tool in inertial navigation systems or in the control of objects in motion (aerial vessels, mechanical vehicles). The article also presents an application of the system as a limb motion capture device.