The effect of coplanar sensor spacing on determining the angular acceleration of vehicles

Vehicle vibration presents challenges to a packaged product that is inevitable in any distribution environment. Typically products are tested in only a single, vertical axis; researchers have shown that there is energy in all six axes of motion. In this work, we study the recording methods of the six degrees of freedom (6DOF) motion of a transport vehicle. Using a co‐planar sensor array, three tri‐axial linear accelerometers and three angular rate sensors mounted in a L shape are used to calculate the rotational accelerations that occur in the back of a vehicle. Missing from prior work is a scientific study designed to determine the minimum sensor spacing necessary to accurately capture the yaw, pitch, and roll of transport vehicles. A sensitivity study is conducted to determine the effect of the misplacement and misorientation of sensors on the angular acceleration calculation. A laboratory study is used to determine the distance error begins to accumulate in the angular acceleration calculation in response to a sinusoidal input. A field study is conducted to calculate the rotational motions of a vehicle on a rough road. It is found that a mounting fixture is valuable in assuring the necessary sensor placement accuracy needed to accurately determine angular accelerations of a truck. Additionally, laboratory and field analysis show that as the sensor spacing location approaches the origin sensor, angular acceleration calculation error increases due to a loss in distinctiveness. It is desired for a close sensor mounting array, but there is a trade off between measurement accuracy and compactness of the recording array. A limit exists where the sensors can not be mounted in close proximity.