Team Vision for System-Level Design PhaseDuring this phase, we planned to verify our systems level design choices, and begin the design of our system at a sub-system level. We were able to complete the subsystem design, and make many high level decisions to support subsystem design.
Problem DefinitionThis project focuses on the development of a Electric Motor Test Bench for RIT's Electric Vehicle Team. This project is designed to test the capabilities of the motor of an electric vehicle when used in conjunction with a motor control unit. The test bench will apply a dynamically variable load to the motor and controller, and then measure how these components react to the given conditions.
Customer RequirementsCustomer Requirements were developed from meetings with the EVTeam, as well as various "startup packages" from the EVT team. We have further refined some of these requirements as per meetings with the EVTeam.
Engineering Specifications were developed based off of the results of the Functional Decomposition, as well as from the Customer Requirements. These specifications have been further refined as per meetings with the EVTeam
PurposeDuring our systems level design, we wanted to take a look at the way that similar problems had been solved in the past, and ensure that our initial systems design had been validated by previous endeavors.
Previous Patents and Products
Systems Level AnalysisThe team took a top-level down approach to the defined problem using tools like functional decomposition and pugh analysis. From a systems perspective, the general design was mostly defined already in the PRP document and via our discussions with the customer. Thus, the systems design phase started broaching topics within the upper echelons of the subsystem level. As seen below, we've already been able to make some decisions about subsystem design and begin acquisition of materials.
Requirements Tracabilility MatrixThe Requirement Matrix was used to guarantee coverage and traceability of the Customer Requirements, as well as avoiding non-useful Engineering Specifications.
PurposeWe completed the Functional Decomposition as a method to verify that our engineering requirements were represented by subsystems in the functional design of the system. We found this to be a very effective exercise, and upon revisiting our functional decomposition after defining our systems level design, we found that none of the decomposition needed to be changed, but we added Engineering Requirement labels to each section for reference.
Systems Level Functional Decomposition
Subsystems Concept Development
Load Generation SubsystemThis subsystem is intended to generate the physical dynamic load on the system.
Final ChoiceThe Electric DC Load Generator will allow for simple torque control, with an added element of safety for the UUT, as the load will be limited by the load resistor. We proved out the concept using a quick lab procedure, performed originally in Dr. Lyshevski's Mechatronics course. The video of our trial can be found below.
Central Test Controller SubsystemThis subsystem is intended to generate load and throttle commands, as well as processing the sensor signals.
- GPIO Adapter
- dSPACE Hardware
Motor Coupling Subsystem
ConceptsThis subsystem is designed to allow a connection between the test motor and the load generator, also allowing "easy" swapping.
Below is an example calculation we used to establish shaft diameter requirements:
Final ChoiceThe final choice for this subsystem will be made during the next design cycle.
Bench Structure SubsystemThis subsystem is intended to provide the framework of the whole system.
- Pre-made bench, adjust to our needs
- Scrap Bench
- 8020 Extruded T-slot Aluminum
Extruded Aluminum framing: Allows us to purchase exactly what we need, provides many interface options and is very robust
- Time with EVT Controller and Parts
- Budgetary Concerns
- Heat Dissipation
- Programming Interface
- Electrical Safety
- Mechanical Safety
Systems Level Test Plan
Project PlanThe high level vision for the project is to develop a prototyping platform for electric vehicle motor components and controllers. The platform should be safe, usable, and provide valuable unit test data to EVT engineers.
A more detailed project schedule can be found below, which goes into specific tasks associated with this project.