PROJECT IDEA SUBMISSION Team Contacts - 1 st person listed serves as the point of contact with Professor Nelson - Initial team size may be from 1 to 6 members (all members must agree to have their name included) NAME Joel Redmond Connor Bushman EMAIL Redmond0@purdue.edu cbushman@purdue.edu Note: Course policy prohibits projects involving drones, weapons, or significant safety risk. PROJECT NAME FSAE Rear Wheel Steering Research and Investigation PROJECT DESCRIPTION The purpose of this project is to determine the viability of implementing a rear wheel steering system into Purdue University s Formula SAE vehicle. Although no direct design work will be done for the vehicle itself, this project will to serve as an initial investigation to determine what kind of positive or negative changes in vehicle performance an implementation of this system- may cause. As per FSAE 2018 Rules: T6.5.5: Rear wheel steering, which may be electrically actuated, is permitted but only if mechanical stops limit the range of angular movement of the rear wheels to a maximum of six degrees (6 ). This must be demonstrated with a driver in the car and the team must provide the facility for the steering angle range to be verified at Technical Inspection.
WHAT IS THE PROBLEM YOU ARE TRYING TO SOLVE? Does implementing rear wheel steering at a small scale yield enough of an improvement to vehicle performance that it would be beneficial to implement it at full scale. EXPLAIN THE PHYSICS OF THE PROBLEM. Include Free-body diagrams or other sketches as necessary. The steering mechanism will most likely be controlled through a four-bar linkage via an electronic actuator. In order for the test vehicle to give accurate results, a basic suspension and differential system will need to be employed. Most four-wheel steering consumer vehicles operate in two modes. At low speeds the front and rear wheels steer in opposition of each other to move the pivot point forward allowing for better maneuverability. At high speeds, the rear wheels steer in conjunction with the front to allow for better stability. The exact parameters for this change in mode of operation for the Formula car will have to be determined. WHY IS IT A PROBLEM? (WHY IS IT WORTH SOLVING?) Points are given out at FSAE competition for creativity. Purdue FSAE often gets zero points in this category. So far, few or even no teams have employed a rear wheel steering system. If Purdue FSAE is the first team to employ such a system, this would give them an advantage in the competition point wise. Additionally, if such a system is proven to be successful in increasing vehicle performance, this would help the team score higher in other events such as skid pad, autocross and endurance.
DESCRIPTION OF YOUR PROPOSED SOLUTION(S). Describe the functional requirements for the final product. Include preliminary sketches of the initial concepts, and explain how they are innovative. The system will most likely be operated using a rack and pinion system, similar to the one used in the front of the vehicle. This one will most likely be operated through a servo motor that is liked to a steering position sensor attached to the front wheels, allowing for a front to rear turning ratio to be determined. The test vehicle will either be built from scratch or will be modified from an RC vehicle, depending on the exact performance specifications to be determined later in the project. The overall weight and complexity of the system will have to be kept to a minimum. Additionally, because electrical problems are a constant struggle for the team, a mechanism must be in place that will allow the system to be disengaged Once the model is designed and tested, various possible methods of integration with the current vehicle will be recommended based on geometry and competition rules. EXPLAIN HOW THE PROTOTYPE WILL BE BUILT & TESTED. A scale model of the 2018 vehicle will need to be built in order to compare the two performance modes; one with the new system, one without. This model will be required to have a degree of kinematic similarity to the original vehicle. This similarity will have to come from suspension performance, tire grip and torque. The prototype will be controlled electronically using either MyRIO or Arduino interface and will have to switch between the two performance modes either through a hardware or software change Materials will be either be ordered online or 3D printed in ME. Any welding can be done at BIDC and machining will be done in the ME Machine Shop. Once the prototype is built, it will be tested against itself around scale models of the competition tracks. Data will be taken with and without rear steering actuation. Depending on operator performance and consistency, these tests will either need to be controlled either remotely or autonomously. Various data will be taken to gauge performance including, lap times, accelerometer data and operator feedback. WHAT ENGINEERING PRINCIPLES WILL BE USED ON THE PROJECT AND HOW? The first and most important aspect that must be considered throughout the project is user safety. There must be a fail-safe mechanism in place due to the instability that a failed dynamic rear wheel steering system would add to a vehicle.
Furthermore, this project can be broken down in to four key areas including vehicle dynamics, system controls, hardware integration, and mechanism design. MARKET ANALYSIS: Who are the target customers and how will they benefit from your proposed product? The target customer of this project is the Purdue Formula SAE Team, specifically the lead suspension designer. This project is beneficial to them because it allows the research to be done that they may not have the time or personnel to do otherwise. This project will also contribute to overall team knowledge that can be passed down for future years. This preliminary research for that can aid in future chassis and suspension design by giving the designers information on what kind of problems to expect during on implementation and possible solutions to mitigate them. BENCHMARK RESEARCH: What solutions exist today and how is your proposed product solving the problem uniquely and better? Describe relevant patents and commercial products including their functional performance and cost. More and more consumer vehicles are employing rear wheel steering as electronic integration becomes more prevalent. This is most common in large vehicles such as large charter busses, construction equipment, and semi trailer s due to the increased maneuverability. The reason this is less common in racing is one topic of research that must be considered before any design work begins. Patent US4856606A describes a fail-safe locking mechanism in the event that the electronics fail. Patent US5019982 gives a method of how each wheel should be controlled given different cornering parameters. WO2009156738A1 is a patent application that is similar to the system proposed here, with additional considerations of how this would relate to a commercial passenger vehicle. HOW WILL THE SOLUTION CREATE BUSINESS AND/OR SOCIETY VALUE? This project will offer Purdue FSAE value by giving them the tools they need to improve their design score as well as vehicle performance in future vehicles. If it is determined that the benefits of four-wheel steering is not worth the added weight
and complexity, it also offers the team value by giving them that knowledge base and experience. Save the file with the following nomenclature: project name - point of contact full name.docx Email completed form to Professor Nelson at tnelson1@purdue.edu to request project approval.