vibration control by a semi-active air spring system in high frequency by pid controller in engine test cell

today there are different vibration isolators used in industries according to the weight and excitation frequency of the machines which have vibration. one of them is air spring which is in two types: convoluted air spring and membrane air spring. convoluted air springs are used to control vibrations in low frequency (usually lower than 10 hz) and the membrane ones are used in high frequency (upper than 20 hz). middle frequency is between 10 and 20 hz. other vibration isolators are being used for this frequency range. in this paper an air spring system was made using lvdt, as the linear measurement sensor, accelerometer with pid controller and convoluted air spring. as mentioned convoluted air springs are used in low frequency but by using conclusions of this research we can use it in high frequency (about 50 hz). finally, an optimum vibration isolator has been made which reduces the vibration amplitude from 2.7mm to 0.15mm (about %87.5 reduction in vibration amplitude). finite element analysis results have been compared with experimental results. there is a good adaption with approximately %8 error. this research has been done according to “irankhodro powertrain company” request for controlling of engine test stand vibration.