Mitsuba used MathWorks tools to model, simulate, verify, and generate production code for the reversing wiper system control. Before beginning the project, Mitsuba took steps to ensure a smooth transition to model-based development. Engineers attended 10 days of onsite training, and the group drafted modeling guidelines and a design procedure. To foster the engineers’ continued education, Mitsuba developed skill standards based on JMAAB Style Guidelines, established by the Japan MATLAB® Automotive Advisory Board and based on Embedded Technology Skill Standards. At the same time, Mitsuba was promoting the use of models and simulation to accelerate development, increase quality, and improve communication both internally and with customers.
Working from the specification, Mitsuba engineers used Simulink® to model control structures, control functions, and test harnesses.
With Simulink and Simscape Multibody™ the group created a plant model, which included the windshield wiper link mechanism, wiper arms, and body mount.
They ran closed-loop simulations using the control system and plant models to verify the functionality of the controller and determine how the physical specifications of the wiper would affect motor control. Based on these simulations, the team performed variable scaling to create a detailed control model.
Using Simulink Coder™, they generated C code from the control and plant models, which they used to conduct software-in-the-loop and real-time processor-in-the-loop simulations. To perform hardware-in-the-loop simulations, they used the test harness created with Simulink and Stateflow® to drive the plant model code on an embedded processor.
The engineers used Embedded Coder® to generate production code for an NEC 78K series 8-bit microcontroller, and then conducted final tests on the production hardware.
The reversing wiper system is currently in production, with monthly shipments of 20,000–30,000 units.
Mitsuba engineers are reusing components of the wiper system and plant model on current projects. The company has standardized on model-based development for all new projects, including motor control products for hybrid and electric vehicles.