Comparison of three different kinematic sensor assemblies for locomotion study

The decrease in the costs of electronic components and devices, conjugated to the advancement of the miniaturization technologies, has promoted a large profusion of the use of motion sensors for human movement analysis in clinics. The errors in the design are numerous, from circuital errors to positioning and orientation errors; a preliminary approach to the problem by means of simulations is necessary. We developed an environment for the simulation of mixed kinematic sensor assemblies with accelerometers and rate gyroscopes; it was tested by means of three different assemblies in the simulation of the trajectory reconstruction. The first assembly was represented by a 6-accelerometer assembly, the second by a 9-accelerometer assembly and the third was based on three rate gyroscopes and three accelerometers. The circuital error, given as an input to the environment, was determined during a bench test, the positioning error was set to P-e = 5 x 10(-4) in and the orientation error to alpha(e) = 6 x 10(-2) deg. Results showed the agreement between estimated and experimental data from the bench test. Simulation results also showed that the errors in trajectory reconstruction in the sagittal plane were lower than 3-4% during 4 s of simulation.