P19231: Training Wheels
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

The Detailed Design Phase lays the groundwork for the ultimate project deliverable. Through detailed drawings, calculations, simulations, and flow charts, other engineers should be able to reconstruct our project. In order to form these detailed documents, the O-Shift team separated into smaller units to tackle tasks that suited our disciplinary strengths.

Steven K

John J

Kevin G

Kevin R

Matt W

Tyler S

Prototyping, Engineering Analysis, Simulation

We used the prototype clutch pedals from our Systems Design Phase to aid in our solution path for this phase. The prototype clutch pedal that was determined most reliable has been displayed again for convenience.

Selected Prototype Clutch Pedal

Selected Prototype Clutch Pedal

From there, a CAD model was constructed in Solidworks so that a static analysis could be conducted and a working drawing could be created. The lengths of the beams in the model could be resized and retested in the software.

SolidWorks Pedal Assembly in the Rest Position

SolidWorks Pedal Assembly in the Rest Position

SolidWorks Pedal Assembly in the Depressed Position

SolidWorks Pedal Assembly in the Depressed Position

Static Test 1: Stress Analysis

Static Test 1: Stress Analysis

Static Test 1: Strain Analysis

Static Test 1: Strain Analysis

Static Test 1: Displacement Analysis

Static Test 1: Displacement Analysis

There were many ideas for the mechanical design of the shifter module. Three designs were chosen for their simplicity and size. The three designs are shown below.

 The ball & socket shifter design with the lockout plate that was added after prototyping

The ball & socket shifter design with the lockout plate that was added after prototyping

 The 2 hinges shifter design with the lockout plate that was added after prototyping

The 2 hinges shifter design with the lockout plate that was added after prototyping

 The sliding shifter design with the lockout plate that was added after prototyping

The sliding shifter design with the lockout plate that was added after prototyping

Prototypes were built for each of these designs from available scrap wood and hardware. Their pictures are below.

PROTOTYPE PICTURES

 The front view of the ball & socket prototype

The front view of the ball & socket prototype

 The top view of the ball & socket prototype

The top view of the ball & socket prototype

 The front view of the 2 hinges prototype

The front view of the 2 hinges prototype

 The top view of the 2 hinges prototype

The top view of the 2 hinges prototype

 The front view of the slider prototype

The front view of the slider prototype

 The top view of the slider prototype

The top view of the slider prototype

Friction between the wooden components caused a large issue in the slider prototype. This was mitigated by soaking the wooden pieces in water and freezing them. If this design were to be more practically built, lower friction materials and ball bearings would likely be used.

The prototypes were compared to each other as well as to the motion and feel of a real manual shifter to generate the benchmarking table below.
 Shifter Benchmarking

Shifter Benchmarking

The ball and socket design was ultimately selected. Its feel of movement closely resembled that of a real manual shifter.

After the shifter prototypes were built, there was a discussion about a lockout mechanism. A brainstorming session resulted in the idea for 2 sliding lockout plates driven by solenoids. The plates and their function are demonstrated below.

 The red lockout plate is depicted here in the closed position

The red lockout plate is depicted here in the closed position

 When the clutch is depressed, the lockout plates will be pulled aside by the solenoids, allowing the shifter to be put into a gear

When the clutch is depressed, the lockout plates will be pulled aside by the solenoids, allowing the shifter to be put into a gear

 The shifter is now put into a gear, and a limit switch will be triggered

The shifter is now put into a gear, and a limit switch will be triggered

 When the clutch pedal is released, the plate will apply pressure to the shifter to hold it in place. The shifter can still be pulled out of gear if necessary

When the clutch pedal is released, the plate will apply pressure to the shifter to hold it in place. The shifter can still be pulled out of gear if necessary

Below is a rough idea of what the cabling routing inside the shifter is going to be.

 Top View of Cabling Inside the Shifter for the Sensors

Top View of Cabling Inside the Shifter for the Sensors

 Side View of Cabling Inside the Shifter for the Sensors

Side View of Cabling Inside the Shifter for the Sensors

OBD-II Data Logging

A PiCAN shield was used to interface a Raspberry Pi 2 with the vehicle (Chevy Cruze) CAN bus, and an open-source Python script was used to log vehicle speed, RPM, and throttle position.
RaspberryPi With PiCAN Shield

RaspberryPi With PiCAN Shield

The RaspberryPi setup shown above was used to collect data parameters from the Chevy Cruze's OBD-II port. Some data that was collected is shown below (speed and RPM). This first data log lasts approximately 18.3 minutes.
Speed and RPM Driving Data

Speed and RPM Driving Data

The following shows a 1st gear acceleration run extracted from the logs with a 2nd order polynomial fit curve.

1st Gear Acceleration Run

1st Gear Acceleration Run

Below presented the RPMs achieved by the the first three gears during the test.

 Gear RPM Data

Gear RPM Data

This represents our 1st attempt at proper data collection, but there is still work to be done on the script used to communicate over OBD-II to achieve higher sample rates for each of the parameters, as well as adding BNO055 IMU data to the logging procedure as well. Below is the data collection scenarios we are going to be recording, this list is a work in progress:

Drawings, Schematics, Flow Charts, Simulations

From the SolidWorks model of the clutch pedal, rudimentary drawings were created of the assembly and all the individual components. Please note that these drawings do not currently incorporate tolerancing and exist largely for display purposes. Drawings may be subject to change and will be updated in the final Detailed Design Phase. Engineering drawings were not created for COTS items.

Clutch Pedal Assembly Drawing

Clutch Pedal Assembly Drawing

6

6" Beam Drawing

6

6" Beam with Hole Drawing

5.5

5.5" Slotted Beam Drawing

Pedal Mounting Unit Drawing

Pedal Mounting Unit Drawing

Pedal Drawing

Pedal Drawing

Piston Drawing

Piston Drawing

Our team is further considering acquiring stainless steel and machining the parts, particularly the beams, brackets, and pedal mounting unit, ourselves. The Bill of Materials, presented later on this page, outlines the components and materials needed to create the clutch pedal unit.

Display Board MCU Pinout

Display Board MCU Pinout

Display Board Schematic

Display Board Schematic

The display board MCU is an STM32f446RET which has control over the data communication lines between the different systems. There are two CAN busses for ODB-II and system communications, SDIO for data logging to an SD card, I2C for IMU communication, and QSPI for communicating with the display controller.

Software Architecture

Software Architecture

This software architecture is an adaptation of the architecture used at RIT Electric Vehicle Team. It is comprised of several layers, starting with the hardware itself and becoming more abstract as you work your way up. Layer-agnostic functionality such as the Task Manager and Error Handler aid in program flow and fault detection.

Bill of Material (BOM)

The following is a very rough Bill of Materials created to achieve a basic understanding of the components we will need as well as a basic idea of pricing. Our team has a definite need to search for more money.
Rough Clutch BOM

Rough Clutch BOM

Rough Shifter BOM

Rough Shifter BOM

Rough Display BOM

Rough Display BOM

Test Plans

A working document of Test Plans for the Upcoming Phase can be seen below.

Test Plans

Test Plans

Risk Assessment

During this new phase, there has not been any change to the risk assessment.

 Risk Assessment 1

Risk Assessment 1

 Risk Assessment 2

Risk Assessment 2

 Risk Assessment 3

Risk Assessment 3

Plans for next phase

Updated Gantt Chart

Updated Gantt Chart

Steven K

John J

Kevin G

Kevin R

Matt W

Tyler S


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