RoboCup: Redesign 2014-2015

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Phase I: Techanical Analysis

The first stage of the 2014-2015 RoboCup redesign involves brainstorming potential upgrades by researching new technologies/resources since the last revision. A parallel analysis of current robot bugs and potential enhancements is also done at this time. Outlined below is a listing of resources that the team used in this brainstorming stage.

Competition 2014 documentation

Team Description Papers (TDP)

Electrical Board Error Logs

Past Electrical Designs

Phase II: Design

During the design phase, specifications are determined for each section of the robot. Experimental results are documented here from all quantitative findings. This phase is also where the high-level ideas from Phase I are tracked to ensure completion.

Logical Controlling Unit

mbed Debugging

To Do

  • Successfully communicate over SPI with a current FPGA and mbed

Completed

  • Build development board for testing FPGA configuration from mbed's flash storage
    • Tested and confirmed working
  • Obtain mbeds for robot use
    • How: 15 mbeds donated by ECE department

Mechanical/Electrical Integration

Max PCB Dimensions

To Do

  • Determine location and placement for dribbler motor header
  • Determine optimal placement direction for drive motor's phase connections (motor board)
  • Add connection header for ball sensor to control board
  • Add wires among connections in CAD assembly files
  • Test motor wire modifications before working on the entire batch of motors
  • Determine kicker connections and integration
  • Determine options using quarter-turn screws for electrical board attachment

Completed

  • Update hall connection header to right angled one
  • Add pin locations to all connection housings in CAD part files
  • Update the 14-pin connection header (female) for the control-to-motor board connection
  • Finalize method for adjusting motor wire lengths when motors arrive
    • Decision: Unsolder from motor's PCB, trim to length, and resolder to motor's PCB
    • Reason: Did not want to delay ordering motors any futher & hand soldering results in higher yields compared against hand crimping
  • Determine placement of battery location

Radio

CC1101 C++ library

nRF24L01+ C++ library

Current protocol [LINK TO BE CREATED & UPDATED]

To Do

  • Determine optimal secondary frequency for base station updates
  • Test methods using breakout boards and compare data rates
  • Successfully communicate using two (2) nRF24L01+ transceivers and two (2) mbeds
  • Research and determine best steps for structuring radio protocol with primary and seconday frequencies
    • The Crazyflie project has basic radio documentation for how they implemented real-time communication with room for expansion
  • Test packet optimizations - Nanopb is promosing for this

Completed

  • Research integration options of the CC1111 and nRF24LU1+
    • Decision: Do not use SoC parts for the base station
    • Reason: Keep radio software on the mbed platform's C++ libraries (SoC would require additional C code for the base station)
  • Order five (5) CC1111 transceivers from TI
  • Successfully communicate using two (2) CC1101 transceivers and two (2) mbeds
  • Obtain breakout boards for CC1101
    • How: Added SMA antenna connector to breakout boards from 2008 fleet
  • Obtain breakout boards for nRF24L01+
    • How: eBay

FPGA

A few major change to the FPGA's Verilog code must be made for the 2015 redesign.

Setting up a computer for Verilog development

  1. Create an account on Xilinx's website
  2. The Xilinx program is called ISE Design Suite (this is on ECE's virtual lab pool computers - can connect to it from anywhere).
    • The desired download link is found under the ISE Design Suite heading
    • The current version at the time of this writing is 14.7 (size: ~6GB)
    • The ISE Design Suite is no longer supported
    • The newer version of Xilinx's software is called Vivado Design Tools, but it does not support the Spartan-3E FPGA
  3. Install the program to your computer
    • The installer will prompt you to select an edition to install
      • Select ISE WebPACK
  4. Obtain a license at the Xilinx page for license management
    • Open the link sent to you after requesting a license
    • Navigate to the Manage Licenses tab
    • Download the license called ISE WebPACK License
  5. Save the downloaded license file to the Xilinx directory of your computer
    • The program will require you to locate the license's path at first startup

Mandatory user-provided files for Verilog synthesis

  • Verilog files(s)
    • Defines the HDL implementation
    • File Extension: .v
  • Xilinx Constraint File
    • Defines parameters for correct synthesis to the hardware (pin mappings)
    • File Extension: .ucf

FPGA Commands

Command Read/Write Definition
0x00 Read Only Receive Data Readings
0x01 Read/Write Set motor speeds

Example SPI Transfer (Read)

Array Index Bit(s) Definition
0 7..0 FPGA Version (0x04 in 2014)
1 7..0 Encoder 1 Count (LSB)
2 7..0
 Encoder 1 Count (MSB)
3 7..0
 Encoder 2 Count (LSB)
4 7..0
 Encoder 2 Count (MSB)
5 7..0
 Encoder 3 Count (LSB)
6 7..0
 Encoder 3 Count (MSB)
7 7..0
 Encoder 4 Count (LSB)
8 7..0
 Encoder 4 Count (MSB)
9 7..0
 Motor Fault
10 7..0
 Kicker Status
11 7..0
 Kicker Voltage
12 7..0
 Hall Count 1
13 7..0
 Hall Count 2
14 7..0
 Hall Count 3
15 7..0 Hall Count 4
16 7..0
 Hall Count 5

Example SPI Transfer (Write)

Array Index Bit(s) Definition
0 7..0 Packet Type (0x01)
1 7..0 Motor 1 Speed (LSB)
2 7..4

Reserved (Always 0x00)

3..2 Motor 1 Drive Mode
1..0 Motor 1 Speed (MSB)
3 7..0 Motor 2 Speed (LSB)
4 7..4 Reserved (Always 0x00)>br/>
3..2 Motor 2 Drive Mode
1..0 Motor 2 Speed (MSB)
5 7..0 Motor 3 Speed (LSB)
6 7..4 Reserved (Always 0x00)
3..2 Motor 3 Drive Mode
1..0 Motor 3 Speed (MSB)
7 7..0 Motor 4 Speed (LSB)
8 7..4 Reserved (Always 0x00)
3..2 Motor 4 Drive Mode
0..1 Motor 4 Speed (MSB)
9 7..0 Dribbler Motor Speed (LSB)
10 7 Kicker Charge
6 Chipper Enable (1=Chip, 0=Kick)
5..4 Reserved (Always 0)
3..2 Dribbler Motor Drive Mode
1..0 Dribbler Motor Speed (MSB)
11 7..0 Kicker Power (<, oxFF=6ms)

To Do

  • Transition the I2C bus lines to the microcontroller
  • Update Verilog for new balanced encoder signals (A+, A-, B+, B-)
    • ( (A+) + (A-) == 0 ) should be true for no errors
  • Update Verilog for driving a bootstrap circuit
  • Add a writable register for enabling/disabling motor encoders

Completed

  • Document steps for synthesizing Verilog files
  • Successfully configured an FPGA from the mbed's on board flash storage
  • Successfully synthesized a Hello World Verilog file using Xilinx's ISE Webtools
  • Determine what communications occur over the SPI bus
    • Documented in the tables above
  • Finalized that the 2015 motors will use the current FPGA
    • Decision: Xilinx Spartan-3E
    • Reason: FPGA is only used for motor control & no futher capabilities are needed

Motors

Maxon 50W Custom Motor Drawing

Maxon 50W Motor Datasheet

To Do

Completed

  • Order 3 DRV8301 Pre-Drivers from TI
  • Finalize the protyping designs of single motor controllers
  • Order motors

Motion Sensing & Motion Control

MPU-9250 C++ library

PID C++ library

To Do

  • Integrate the MPU-9250 into the I2C data bus lines from the mbed

Completed

Error Detection & Indication

To Do

  • Determine best solution for controlling the WS2812B RGB LED

Completed

Kicker Board

To Do

  • Measure the current from kicker boards currently used
  • Update the kicker board to accommodate the new battery's voltage of 18.5V

Completed

Battery & Power

The following contains a listing of batteries that were considered for the 2015 design along with other battery/power adapters and accessories.

To Do

Completed

Battery

Zippy Flightmax 2200mAh 5S 40C

Connector

XT60 (Male)

XT60 12AWG 10cm

Charging Lead

XT60 Banana Plug

Balancing Board

Charge/Balance Board

All Batteries

Zippy Flightmax 2500mAh 5S 20C

Zippy Flightmax 1800mAh 5S 40C

Zippy Compact 2450mAh 5S 35C

Turnig 2200mAh 5S 30C

Thunder Power 2000mAh 5S 16C

Phase III: Production

The final phase for creating the new fleet of robots involves outlining the steps and procedures for robot manufacturing and assebly. Future members can use this area as a reference for the fleet's required maintenance. It may also be benefitial for strengthening tolerances in future fleet builds.

Electronics Assembly

Solder Paste Stencil Creation

https://learn.sparkfun.com/tutorials/electronics-assembly

http://www.soldermask.com/ <- Sparfun uses these guys for all their solder stencils

  • Kapton film & laser cutter
    • Tested and not precise enough
  • Chemical etching aluminum
    • Untested but very promosing
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