Active system for vibration isolation and acceleration compensation for vehicle embarked equipment and persons; ACTISEAT
The ACTISEAT project aims at the development of an active system to isolate, up to a certain extent, the equipment and persons inside a vehicle from the accelerations generated during the vehicle in motion. System mechanical architecture is based on a 4-DOF spherical motion system. DOF's are: roll, pitch, yaw and heave. Many are the direct fields of application of the technology developed in ACTISEAT project. The specific system to be developed for each application differs only in the maximum system excursions. Potential applications are: -Driver seat, standard vehicle. -Passenger seat, standard vehicle. -Operator seat in main cabin, heavy machinery. -Operator seat in auxiliary cabin, heavy machinery. -Ambulances. -Fragile goods transportation. -Special cases: entertainment, etc. The prototype developed in this project is a vehicle active seat. Its motion excursions are the following: Excursion limits and final definition: -Roll: 20 degrees. -Pitch: 20 degrees. -Yaw: 20 degrees. -Heave: 12cm. The system operates in the following way. Static or dynamic lateral and longitudinal vehicle accelerations can be compensated by means of seat tilting. This strategy is only valid for sustained vehicle accelerations. To compensate vehicle vertical acceleration, ACTISEAT works as an active suspension system. The seat has been completely built and tested. Electrical servomotors drive the prototype. Control is implemented on MATLAB software. The most remarkable test results have been the following : 1) Tested in laboratory conditions and also embarked in a real vehicle, ACTISEAT was able to compensate 100 % of the vehicle longitudinal and lateral accelerations and also static vehicle inclinations. Limitations are: -Acceleration can not be fully compensated if its magnitude exceeds the corresponding maximum ACTISEAT tilting angle for the present prototype. -Acceleration can not be fully compensated if it appears abruptly, that is, if the over-acceleration is important (i.e. in case of vehicle collision, sudden braking manoeuvres, etc). 2) For vertical accelerations, the main results obtained in the tests were: -In lab tests: seat mounted on a motion base providing vertical sinusoidal motion, band 0.5-2 Hz: ACTISEAT compensates approximately 66% of the vertical acceleration generated by the motion base. -In lab tests: seat mounted on a motion base providing vertical sinusoidal motion, frequency band over 2 Hz: ACTISEAT does not compensate actively vertical accelerations, although some portion is absorbed by the elasticity of the seat foam (as all vehicle seats do in any case). -Test on a real vehicle: vehicle vertical motion is perceived, attenuated in any case.