Modeling the Raven SCS-700 Chemical Injection System with Carrier Control with Sprayer Simulation
Mathematical models of the chemical and carrier control sub-systems of the Raven SCS-700 chemical injection system were developed. The step responses of both control sub-systems were predictable using the models. From this process of model development, it was observed that the voltage saturation effect limited the response speed of the carrier valve motor and the resulting speed at which changes could be made to the carrier flow rate. The rate at which flow rate measurements were available limited the extent to which valve motor speed could be increased without causing instability. The performance of three different types of sprayers was simulated using these models. Simulations were performed with and without carrier control. Sprayers using carrier control misapplied to smaller areas than those without carrier control. Differences between the response of the chemical and carrier sub-system controllers produced concentration variations that contributed to application error. These errors, however, were small relative to the errors caused by response times of both systems and the ground speed sampling rate.
This article is from Transactions of the ASAE, 43, no. 2 (2000): 231–245.