MTS mHIL Steering Test System
The MTS mHIL Steering Test System integrates a 3 or 5-channel physical test rig into the loop of a real-time model to gain insight into a new steering system’s impact on vehicle behavior earlier in the vehicle development cycle.

Steering Toward Innovation

MTS Application Engineer Ford Boone, who has 12 years of experience in ground vehicle testing and development, discusses how challenges posed by new electronic steering systems are driving laboratory-based test innovation.

Q: What are the opportunities and challenges posed by new electronic steering systems?

Boone: Electronic steering systems are changing very rapidly. The pace of innovation has picked up because these systems enable vehicle developers to simultaneously improve the efficiency, handling, comfort, and safety, all enhancing the driving experience for their full range of vehicle offerings. The complexities of these systems over traditional hydraulic steering systems pose new challenges to vehicle developers in characterization, trying to recreate the traditional “feel” drivers expect, and in new interactions of the steer subsystem with other vehicle subsystems.

Q: What are the implications for vehicle developers?

Boone: Evaluating hydraulic systems is relatively straightforward and designs can be verified on the test track. This isn’t the case with electronic steering systems, which dramatically increase the amount of testing that has to be done. There are new tuning parameters to set-up and evaluate for steer compensation algorithms such as wind pull, road crown and other complex conditions. There are new technologies to optimize such as active steering, collision avoidance, and electronic stability control. All of these feature intricate components that are difficult to model. They all add new fault conditions to evaluate and generate complicated vehicle subsystem interactions that standard tools and test methods are currently not designed to evaluate.

Q: How are developers dealing with this situation today?

Boone: Many are using the proving ground for development tasks they previously performed in the lab. This is a very labor-intensive and time-consuming process, and it puts developers in a tough spot. They are expected to incorporate the latest steering system innovations, yet they are under constant pressure to reduce time, cost, and risk throughout the vehicle development cycle. Ideally, what developers want to do is optimize steering systems before the full vehicle prototype is even available. They want to complete the vast majority of development in the lab, and then use the test track primarily for validation. This is the idea behind the mechanical Hardware-in-the-Loop (mHIL) Steering Test Systems from MTS.

Q: How does the mHIL Steering Test System work?

Boone: It uses a hybrid simulation approach, placing the entire physical steering sub-system inside the loop of a real-time full-vehicle dynamic model. Engineers “drive” the car in a virtual environment while simultaneously subjecting the physical steering system to actual mechanical forces and motions. All electric components with all of the real signals and excitations that would be exhibited in the real vehicle are present. This all occurs within the laboratory from a single MTS software interface. 

Q: How does this help developers keep pace with new steering technologies?

Boone: The mHIL steering test system allows steer development engineers to set-up, tune, characterize and evaluate new electronic steering systems within the laboratory, without the full vehicle prototype, earlier in the vehicle development cycle. This allows the development team to start validation at the track earlier equipped with better answers. It also provides a product development and research tool for exploring new steer technologies to differentiate themselves from the competition. Overall, it helps vehicle development teams shorten the validation cycle time, reduce overall development costs, open up test track availability, and incorporate the latest optimized steering system innovations for luxury, midline and economy vehicles.

Q: Are there other advantages to this approach?

Boone: The mHIL system generates more quantitative test data that may not be available through typical track testing. With this data, vehicle developers can improve vehicle models, build more robust prototypes, and advance steer technology.

Q: Is the mHIL system in use today?

Boone: The MTS mHIL Steering Test System is currently being used by a major Japanese OEM, and it has demonstrated correlation to actual track testing for subsystem characterization and overall vehicle evaluation. Plans are under way to deliver an mHIL system to a North American OEM, and potentially several other manufacturers worldwide.

Q: Have vehicle developers found other uses for mHIL technology?

Boone: Yes, MTS also offers mHIL solutions for suspension system development and many other vehicle subsystem applications.

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