Student Projects
Contact Information
Competition Year: 2016
University: Liverpool John Moores University
Team Members (with year of graduation): Dan Mckelvie 2016
Email Address: Dan.McKelvie@hotmail.co.uk
Country: UK
Project Information
Title: Closed Loop Shifting Control
Description: A closed loop shifting control system developed on the MyRIO platform. The system utilizes Hall Effect based feedback to improve the engine shifting system for the LJMU Formula Student car.
Products:
NI MyRio 1900
NI LabView 2013
Hall Effect Sensor Unit
Darlington Pair Unit
The Challenge:
The main aim of this project was to develop the control systems around the shifting system for the LJMU Racing Formula Student car. This focused on improving the reliability of the shifts as well as reducing the time needed for a shift to be completed.
The Solution:
Fig 1. System Flow Chart
The graphical representation above shows the sequence of events that the system uses to change gear effectively and reliably. This system utilises a hall-effect sensor positioned on the outside of the engine and a magnet located on the selector barrier. Using a closed loop feedback signal, the system accurately identifies what gear the is selected using a voltage feedback signal. When an upshift is required, the program sends a signal to the ECU to cut fuel and spark to enable clutchless shifts, save fuel and further decrease shifting times.
An auto-shift feature has been added in order to improve acceleration and launch times, using signal from the ECU based on engine RPM. Further developments of this feature are to look at engine RPM and front and rear wheel speed signals. This will allow for slip to be calculated and further improve reliability and performance of this feature.
A neutral button peforms a half shift, as it is located between first and second gear. The addition of a neutral button will enhance drivability of the car as well as improving safety and time. The neutral feature will allow the driver to select neutral from either first or second gear, using position feedback to relay relevant information to the solenoids from the MyRio through a Twin Darlington pair driver circuit.
Being a graphical programming environment, LabVIEW allowed for rapid development of the system and was able to produce a high quality programme that met the needs of the team. LabVIEW’s implementation of Boolean logic allows for a rapid and efficient transition from an initial flow diagram model of the systems operation to a functional and effective program. The NI MyRio with its versatile set of inputs and outputs allows for the simple implementation of the system with minimal additional circuitry. This coupled with a powerful processer ensures correct operation of the shifting system.
Fig 2. LJMU 15 Rear Shot
A more basic version of the system was used and fully tested for a complete season in 2015, as seen in Fig 2. Further development into closed loop shifting for the 2016 car has been bench tested and is currently under further development on a previous years car.
Fig 3 - Shifter System Testing
The above video shows a successful bench test of the system within the LJMU Workshop.
