Date
Problem
Severity
2/10/2015 UHMW will not be able to support the load
of the device domponents
Major
Bottom pole we received from MSD scrap
2/12/2015 pile was misplaced
Ordinary
Analyze
FEA analysis in CAD shows that the UHMW
material will not be able to support the
weight of all the components
Bottom pole is gone, need to change size
and material of poles since we won't be
using the scrap pole anymore
The springs will not be strong enough to
keep the driving omni-wheels on the ground
to enable device movement, push-pull
cables are not user-friendly since we will
need 4 of them to lift the weight of the
electrical components
Potential Solutions
Final Solution
Replace UHMW with 1/4" Aluminum
Order new poles, change size and
material of poles
Order 3/4" and 1" telescoping
Order new poles, change size and material of pol aluminum poles
Remove omni-wheel lifting functionality,
purchase bigger springs, create
Remove all omni-wheel lifting functionality
mechanical subsystem to pull all 4 cables
The omni-wheel lifting mechanism and
2/17/2015 springs are not feasible
Critical
Ping sensors will not be able to detect
2/18/2015 protruding objects above 12 inches off the
ground (such as tray tables)
Major
The ping sensors have a significant
Add two more ping sensors that are
horizontal detection range, but a very small mounted perpendicular to the existing
vertical range
ping sensors
Add two more ping sensors that are mounted
perpendicular to the existing ping sensors
2/25/2015 Remake two wheel hubs
Major
The surface finish on the hubs was such
that they were not able to be used.
FInish Machining on 2/27/2015 & indicate
deliverable is completed
3/10/2015 Quick Release buttons do not spring back
after release
Major
Battery will not charge, loses charge too
4/14/2015 fast
Critical
Welded motor mounts prevent the bearing
4/14/2015 from lining up with the base, furthermore,
presence of weld does not allow the motor
to sit flush with the mount.
Critical
4/16/2015 Voltage regulators get really hot
Major
4/21/2015
Motor Sides no longer allow clearance for
motors
Major
Implement
Order 1/4" Aluminum through the
machine shop, change material in
CAD model
Thicker UHMW, Aluminum
Spend more time in the machine shop
and edit the deliverable date
1. Try to open up the through hole slightly
The pole is near the the button's minimum in order to allow easier passage 2.
functional diameter causing them to bend a Order new buttons that are rated for a
1. Try to open up the through hole slightly in
little, this makes it difficult for the button to smaller pole ID (.5-1.25" ID: 92988A530 order to allow easier passage
spring back out after use
or .5-.875" ID:92988A510)
The battery charger will not charge the
battery. The circuit requires the thermistor to
be closed and the circuit will not close, as
indicated by the NO LED light on the battery 1. Bypass the breeched cell 2. Purchase 2. Purchase a new battery without an extra
a new battery without an extra thermistor thermistor
charger when plugged in. This could be
3. Charge the battery in the EE Lab
caused by a breached cell in the battery
pack. The battery is also losing charge at a
very fast rate (less than 30 seconds).
1. Mill off 4 millimeters from the base
When the motor rests on the base, the
plate where the motors are located
Redesign motor mounts (longer and taller) ,
motor shaft does not line up with the
2.Remove old motor mounts, redesign
remachine and send back to Rob for Welding
bearing in the motor mount
them, and reweld
2 Voltage regulators in parallel is not very
1. Check wire connections 2.
reliable for getting 12VDC for the arduino
Reconfigure wiring 3. Buy a step down
with out the risk of overpowering the arduino transformer
mega
Due to the increase in height of the motor
Mill out extra material to increase slot
mounts, the motor side no longer allows
height
enough clearance for the motor shaft
Remove the electrical device
platform, don't order push-pull
cables and extra aluminum,
redesign layout of the base and
placement of all electrical
components
We decided not to add two more
ping sensors because it would
further complicate the arduino code
and wiring
Evaluate
Increased strength of base,
lost money since UHMW
was already ordered
Date Problem Solved
2/17/2015
Better fitting and better size
poles were ordered
2/24/2015
Weight of device was
reduced by 11 pounds and
diameter of base was
reduced from 27.5 in. to 22.8
in.
2/24/2015
This is an area for
improvement for further
iterations of this project
4/14/2015
The remade hubs have
Go to the machine shop on Friday
smoother surfaces &
2/27 from 8am-12pm. If needed
connect appropriately to the
also from 12:30-3PM
shafts.
3/9/2015
Go back to machine shop
tomorrow to expand holes
The buttons now fit snug in
the holes
4/14/2015
Receive battery and wire it to the
electrical system
The battery now powers the
system adequately
4/30/2015
Mounts have been machined and
sent back to welding (4/21)
Motor mounts work now
4/21/2015
Buy a new 24V to 12V step down transformer
Transformer doesn't overheat and
Everything works
good connections are made
4/29/2015
Milled out extra material
Finished milling (4/21)
4/21/2015
Motor shafts fit through hole
Critical
The motor can not align properly with the
bearing.
Also the wheels would be missaligned
resulting in further issues.
Un weld the mount, drill, and thread
Un-weld the mount and re-weld to the base to it
holes in the bottom of the mount to fix it
to the base. Talk to Rob for best solution. proper orientation
Motor mount was re-welded to the The motor mount properly
base
now through the bearing.
The Arduino Mega was not responding
5/1/2015 when connecting to a laptop
Critical
Connection problem between board and
laptop. Will not run or receive new code.
Buy another Arduino Mega Board
Bought another Arduino Mega Board
Connected new board to laptop
and verified connection
5/1/2015 RoboClaw Motor controller- the 2nd Hbridge got fried.
Critical
As a result motor #2 will not be powered.
1. Buy a new controller and/or unplug
and run only 3 motors
2. Buy 2 new controllers
3. Create a protective casing for the
motor controllers
Purchased plastic containers and
Buy 2 new motor controllers and create protective toothpicks so that we could press The motor controllers work
casing for motor controllers
the buttons on the motor controller now, without problems
while in the containers
5/7/2015
Major
Center mount screw for outside of the hub
loosens when stand goes backwards and
left.
Re-design system for captivating the
omni wheels to the hub & shaft.
Unscrewed the screws and re-aligned the
system.
5/7/2015
4/29/2015
5/2/2015
While assembling the base. One of the
motor mounts was welded upside down
Motor mounts unscrew after continuous
use
Retractable tether doesn't fit through the
5/2/2015 hole in the base cover
Ordinary
Motor #4 is much slower than the rest of
5/8/2015 the motors
Major
5/8/2015
Critical
Motor controller trace blown
5/11/2015
Major
Encoder is not spinning freely
Critical
Major
Ordinary
Tightened the screws
New board works and
responds to connected
laptop
Tested the movement of the
stand and it worked
The alignment of the motor, bushing, and
mount prevent the motor from achieving
appropriate speed dictated by the code.
1. Drill a bigger hole 2. Remove metal
Drill a bigger hole: 0.5"
piece from tether line
1. Drill the holes bigger
Loosened all the mounting screws, re-aligned the Implemented the Final Solution
2. Lossen and re-align motor & bushing, motor, secure motor to the mount
mupltiple times after testing it each It works
and tighten screws
time.
Motor contoller was too close to case and
cause the trace to short
Encoder not spinning would prevent the
stand
from moving properly as desired.
1. Buy new contoller
2. patch traces
1. spray with WD-40
2. Line the groove of the pulley with
electrical tape
Hole needs to be bigger
Traces are patched
Line the groove of the pulley with electrical tape
4/29/2015
5/1/2015
5/11/2015
5/8/2015
5/8/2015
Added the electrical tape
It works, but more friction is
needed in order to better
track distance
5/14/2015