AN ONLINE ACQUISITION SYSTEM FOR A SECOND ORDER MECHANICAL SYSTEM (R.U.B.E.)

Students often are presented with measured laboratory data which is not tainted by real-world measurement issues such as noise, quantization error and poor sensor sensitivity. The students then perceive the “measurement world” as very much like the analytical theoretical equations that are presented in the classroom environment. This is often done to illustrate a particular theoretical concept (and not “cloud the issue” with real-world, contaminated data). The student then grasps the one concept of interest but is shielded from the actual measurement environment that typically exists. A second order mechanical system is operated in an online, internet controlled experiment where the displacement and accelerations are measured with a variety of different transducers. The selection of transducers spans the range of poor transducer sensitivity, noisy measurements, inadequate resolution and clipped signals. The students must collect the data and process it to numerically integrate and differentiate the displacement and acceleration measurements. A variety of different issues must be addressed in order to cleanse the data of real-world measurement contaminants – filtering, smoothing, bias adjustment are a few of the tools that can be used. The system has variable mechanical parameters—it changes every time it is operated so that no two sets of data are alike (variable input, variable mass, variable stiffness). This forces each student to process his/her own data, as it will be slightly different from data sets collected by other students. The RUBE (Response Under Basic Excitation) is described along with the supporting tools that assist the student in the evaluation of the acquired data.