Battery operated omnidirectional platform

The goal of this project was to work with a mechanical engineering team to create a mobile RC platform for the University of Idaho Marching Band during the band’s performances. 
=Problem Definition=
The Battery Operated Omnidirectional Platform is a continuation of the project called Band on the Run from last year. Our goal is to create a mobile platform that can be used to carry various instruments and personnel. The platform will be remotely controlled by a wireless controller and powered by rechargeable batteries.
==Background==
The University of Idaho Marching Band (also known as the Voice of Idaho) has over a one-hundred years of history. With hundreds of outstanding students, the band provides excellent performances for the University of Idaho sports programs and school events. In 2011, Dr. Edwin Odom, from the Department of Mechanical Engineering, and Dr. Daniel Bukvich, professor of Percussion and Music Theory, started a project to design a mobile drum set to be used during performances by the University Band, which came to be known as the Band-Beesten. This year we're improving on and finishing a new mobile platform which will be much more modular, thus allowing a greater degree of artistic freedom for the Sound of Idaho.
==Deliverables==
Battery operated omnidirectional platform project should operate under these specififications:
 Controlled remotely over a distance of 100 meters
 Powered by lithium based cells
 Have a total payload of 800lbs
 Provide continuous movement and operation for 15 to 20 minutes
Translate and rotate independently from 2 different reference perspectives
Maintain multiple modes of safety and redundancy measures to prevent malfunction or harm to riders
Designed with environmental, global, social, and economic factors as constraints per ABET requirements
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=Design Considerations=
==Overview==
Through the comprehensive consideration of the design specification of the platform, we conclude that the platform needs the following basic requirements:
: 
 System control
 Energy storage
 Electric motors
 Remote communications
==System Control==
System control is an important part of the electronic system of the platform, especially the microcontroller used in the main computing unit of the system control, which includes sensors and energy storage. 
===Sensors=== 
The sensors we are using in this project will allow us to get information such as speed, temperature, current, and voltage. By using encoders, accelerometers, and thermistors, we can ensure safe operation of the platform.
==Energy Storage==
Because the platform needs to translate and articulate about the field whilst moving about 800 pounds, including its own weight, a lot of energy is needed to propel the platform. The use of lithium batteries ensured that a higher power density could be obtained, but to use lithium batteries requires the use of a battery management system (BMS).
Considerations for choosing a BMS were:
the voltage
current
Battery Temp over use
===Energy Management===
The lithium cells are managed using a battery management system (BMS) described in a later section of this page. Battery pack were made using LiFePO4 batteries. A "cell" is then constructed of 8 batteries in parallel. A full battery "pack" then was made from 8 of the "cells" placed in series. Our energy source mitigates many safety concerns associated with more traditional lithium ion chemistries.
==Electric Motors==
When considering a motor, we must consider torque ratings, speed ratings, current consumption, voltage and thermal characteristics in order to ensure the safety and capability of the platform.
===Motor Control===
With regard to motor controllers, we must consider their ability to control speed, torque and acceleration. Current and voltage are also important considerations, as the motor must withstand relatively large currents. 
==Remote Communications==
In order to avoid interference with signals on the platform and to ensure signal integrity, the signal transmission distance had to also be considered. The typical distance considered is half of a football field (50 yards) to a maximum of the entire length (100 yards). In this manner we can ensure all possible variations of movement on a field are accounted for.
=Specifications=
==Major Design Components==
 
Microcontroller 
ESP32 
Key Features
 
 High Clock Speed - 240MHz 32 bit Dual Core Processor
 WiFi/Bluetooth Availability
 34 Software Assigned General Purpose I/O Pins	
 
LiFePO4 cells
A123 ANR26650m1-B<P>
Nomenclature
 Battery[ies]: Individual 3.3 VDC LiFePO4 cells, pictured to the right
 C Rate: Refers to charge/discharge properties. Obtained by dropping the “h” from “Ah” 1
Specifications
 Max Continuous Discharge: 50A
 Peak Discharge: 120A (10s)
 Max Power Density: 2600W/Kg (23°C)
 Cell Capacity : 2.5/2.4 Ah (@ 0.5C Rate, Nominal/ Min)
 Mitigates safety concerns of traditional Li-ion chemistries
 
 Less environmentally impactful
 Improved recyclability
 Wider temp stability range
 
 1 Ex) 1C charging current for 1 battery = 2.5A	
LiFePO4 Battery Packs
Specifications
 Battery Pack: Comprised of 8 Cells, made of 8 individual batteries themselves, pictured to the right.
 
 Nominal Voltage: 26.4VDC (28.8 VDC Max)
 Max Continuous Discharge: 400A
 Peak Discharge: 960A (10s)
 Pack Capacity : 20/19.2 Ah (Nom/Min)	
 
Battery management system 
Roboteq BMS1040A 
Key Features
 Power
 
 Max Cell Pack Voltage: 40V
 Max Number of Cells: 10
 Max Load Current: 100A(continuous), 200A(5s peak)
 Max Charge Current: 50A
 
 Communication
 
 RS485
 USB
 CAN bus
 Proprietary PWM
 
 I/O
 
 Digital inputs: 1
 Digital Outputs: 2
 Temperature Sensors: 3
 
 Mechanical
 
 Conduction Plate Cooling
 Dimensions: 145mm x 115mm x 23mm
 Weight: 250g		
Motor Controllers 
Electromen EM 282 C 
Key Features
 Power Range
 
 Supply voltage: 10-50 VDC (Nominal)
 Idle current typ 20 mA 
 Output Motor Current: 100 A (Continuous)Peak 200A (5s)
 Braking Load Current: 50 A (continuous)Peak 100A (5s)
 Current limit adjustable 1-200 A		
Motors 
AmpFlow E30-400-24-G 
Key Features
 
 2.1 Peak HP Motors
 Nominal Voltage of 24 VDC
 Features reduction ratio of 8.3 : 1
 Output Stall Torque of 64 ft-lbs
Unloaded: 680 RPM and 3.2 A
Output stage further reduced by 3 : 1 sprockets, resulting in total Reduction Ratio of 24.78 : 1 and an Output Shaft Stall Torque of 192 ft-lbs
Omni-wheel’s diameter is 1 foot, thereby maximum unloaded speed of platform theoretically is 8.2 MPH;
Max wheel translational force = (192 ft-lbs/ 0.5 ft) = 394 lbs
Current rotary encoder sensors allow for 0.025 MPH resolution		
=Project Learning=
Learning Goals<P>
 The reason for design
 Systematic summary of the learned knowledge, improve the ability of comprehensive application. In the design  process, a systematic review and summary of the previous professional basic knowledge, professional knowledge, curriculum design and production practice.
 Continue to learn new knowledge, gradually improve the knowledge structure, through theory and practice, improve the ability to solve practical problems.
 Improved our teamwork and communication skills through weekly meetings, reports and discussions, through the exchange of information and ideas, help us to complete the project better.
 Cultivate our comprehensive application of the basic theory and professional knowledge of the ability to solve engineering and technical problems.
 
=Final Design=
The platform consists of four omnidirectional wheels, each driven by an electric motor that is able to rotate and move easily across the field, carries approximately 800 pounds, runs for at least 15 to 20 minutes, and is remotely controlled by an RC controller and receives commands from sensors to receive information, and is powered by a lithium battery source. The lithium cells are managed using a battery management system.
=Additional Documentation=
Code
https://drive.google.com/drive/folders/1xyedKqGsTjozy96BKvYeSZpPIHeirnee
Meeting Minutes
https://drive.google.com/drive/folders/1KGosfL3CM-6RcloYBeyTq2qicFHQb5os
Design Review
https://drive.google.com/drive/folders/1AKPyCWhBV05nmORdXEKZ9gJTPJg-qod6
Budget
https://drive.google.com/drive/folders/19DSChNGeVE9RLb3vltRxdsD86Fh2ls9S
=Team Members=
 
	
Name: Blaine Porter<Br></Br>
Major: Electrical Engineering </Br>
Hometown: Rathdrum, ID </Br>
Responsibilities: 
 Team Lead
 Motors and Motor Controller Subsystems
 LED Light Show Circuit Diagram
Email: port9632@vandals.uidaho.edu or porterswelding@yahoo.com
	
Name: JJ Mackesy 
Major: Electrical Engineering
Hometown: Post Falls, ID
Responsibilities: 
 Controls System
 Wiki Page Support
 
Email: mack0923@vandals.uidaho.edu
	
Name: Taylor Leavey 
Major: Electrical Engineering
Hometown: Clarkston, WA
Responsibilities: 
 Battery Management System
 Finances
 
Email: leav8805@vandals.uidaho.edu
	
Name: Qihang Liu (Prounounced as "chee-hong")
Major: Electrical Engineering
Hometown: Jiangsu Province, China
Responsibilities: 
 Wiki Page
 DFMEA and ABET
 
Email: qiha4313@vandals.uidaho.edu