2015 Kit Review Outline
• What’s Changed for 2015
• Various Topics
David Kwast April 27, 2015
What’s Changed for 2015
2015 Consumable Kit Changes
• Added 3/4” Foam Board
• Removed 1/8” PVC Sheet
• Added 1/8” Polycarbonate Sheet
• Changed 1/4” Diameter Dowel from Hardwood
to Oak (higher quality)
• Changed Length of #10 Socket Head Screw to
1” (3/4” is still allowed)
• Allow Bank Wrappers on Pennies
Consumable Kit
Changes
Increase Length to
1’ (3/4” still okay)
2015 Consumable Kit Changes
• Per the Random Elimination Protocol for 2015
– Removed 3/8” Plywood
– Removed Heavy Door Spring
– Removed 2.5” Hinges
Consumable Kit
Elimination Items
2015 Returnable Kit Changes
• Removed MXL Belt Items
• Added HTD Belt Items
• Removed 9V Cortex Backup Battery Holder
• Removed Optional 1/16” Allen Wrench
• Allow VEX Competition Retention Clips on the
Cortex
Returnable Kit
Changes
VEX Competition
Retention Clip
2015 Kit Related Rules Changes
• Allow Use of Video Capture on the Robot
2015 Kit Topics
VEXnet Keys
The feedback I have received on the new white VEXnet keys has been
good in general. There have still been issues with loss of radio connection
or the inability to establish a connection at all, but there has been a
significant improvement from the old black VEXnet keys. Below is a list of
things to consider if you are having connectivity issues:
Poor connection to main battery
Trouble shooting: Jiggle wires in between the main 7.2V battery and the
Cortex with the unit powered up to find intermittent contact.
Notes: The old style white Molex connector common to the Cortex can
have very poor retention capability (as in almost zero retention
sometimes). The newer black Molex connector has much better retention.
Both styles (white and black Molex connectors) become unreliable if they
are plugged in and out very many times. Remind your students to only
unplug the main 7.2V battery at the PowerPole connector.
Example of White Molex
Connector in Cortex
2012 Kit Tips
To eliminate white Molex, ask VEX for the
Cortex black Molex pigtail connector or
participate in the refurbishment program.
2015 Kit Topics
VEXnet Keys (continued)
Poor connection at USB port
Trouble shooting: Jiggle the VEXnet keys with the units powered up to find
intermittent contact.
Notes: Taping the key in place at the Cortex can help (but not on the
Joystick because tape is not allowed on the Joystick). Using the optional
battery cover thumb screw on the Joystick can help (because it pushes
against the key).
Radio interference from low-profile Cortex unit
Trouble shooting: Try using a USB extender cable to get the VEXnet key
away from the Cortex to see if there is an improvement.
Notes: The VEXnet key is in a greater EMF influence on the low profile
style Cortex. A USB extender cable of up to 18” is allowed per the RK list.
A USB extender may also help if there is a lot of metal surrounding the
Cortex/VEXnet key on the robot.
High profile Cortex with Molex to
PowerPole adapter.
Low profile Cortex with optional USB
extension and Powerpole conversion.
2015 Kit Topics
VEXnet Keys (continued)
No connection at all
Trouble shooting: Try re-establishing the Cortex to Joystick pairing by
connecting them together with a USB cable and then retry the VEXnet
keys. Try different VEXnet keys. Try updating firmware in the Cortex,
Joystick and VEXnet keys.
Notes: We have had good luck solving this issue by doing a firmware
update on all of the components. If this doesn’t work, you probably have a
bad component (or heavy RF interference).
2015 Kit Topics
Cortex
I don’t think we have had a single outright failure of a Cortex at my hub.
Although some units have been cantankerous when it comes to up loading
firmware or a user program, as in requiring more than one attempt to get
the firmware/software to load. The most significant weaknesses of the
earliest units have been resolved (which were as follows); low profile unit
has decreased range and is more susceptible to radio interference
(because VEXnet key is closer to microprocessor); white Molex connector
has poor retention force with interfacing cable (Molex to PowerPole
adapter in our case). Note that if you do the VEX refurbishment program,
these old style units will be replaced with up-to-date units.
Cortex 9V Backup Battery
The ability to use a 9V battery Cortex backup battery/holder will be
eliminated for 2015 (was optional for 2014). Note that unless you are
using the VEX field controller/hardware/switches (which plug into the
Joysticks when teams are competing on the field), the backup battery
doesn’t do anything beneficial (and can cause battery drain if used
incorrectly). I would also contend that the backup battery is just a band-aid
for things that can be avoided in the first place (keep your main battery well
charged and address any poor connections to the main battery).
2015 Kit Topics
Joystick
The only failures I have heard about or experienced are sticky or stuck
buttons. The units seem to be fairly robust in terms of impact damage. I
have seen them dropped on hard floors on multiple occasions, and I
haven’t seen them break yet.
Note that the recalibration procedure is easier with the new white VEXnet
keys; no connection to the Cortex and no VEXnet key required; just turn on
the Joystick and run it through the recalibration steps.
Belts and Pulleys
We expect better performance from the new HTD belts and pulleys. The
old MXL standard is not designed to handle the torque that we are
subjecting them to; belts slip and parts break.
Large Motor
I have received some feedback that some wear related failures have been
occurring in the large motors.
2015 Kit Topics
Motor Controllers
We have seen a fairly high failure rate with the motor controllers at my hub.
Most of the failures seem to be due to shorting out the units (sloppy
wiring). So all of the failures of these units at my hub this past year were
limited to just two teams (who had poor wiring - strands of exposed copper
just waiting to short out), so this doesn’t seem to be a general problem (we
also charged these teams for new units).
Motor Terminal Cables
I highly recommended that stress relief be provided for these cables (see
the “Mods” tab on the kit list spreadsheet); otherwise the wire strands will
break where they run into the metal ferrule at the white terminal end. The
modified cables are much more durable (also helps to prevent shorts that
fry the motor controllers).
2015 Kit Topics
Servos
The servos tend to fail at high rate due to abuse. If the servo is used such
that forced into uncommanded position or is in a state of constant dynamic
oscillation, it is likely to fail. We warn our teams about this at kickoff. We
charge our teams for stripped gears (usually caused by abuse), but give
them a pass if the servo is electrically dead.
2015 Kit Topics
Software
The utility and drivers to update the Cortex and Joystick firmware come
with the easyC installation package, but they can also be downloaded
separately. The utility and drivers to update the 2.0 VEXnet keys is a
separate package.
Latest easyC package: http://www.intelitekdownloads.com/easyCV4/
Firmware utilities:
http://www.vexrobotics.com/wiki/index.php/Software_Downloads
Note that an easyC user program cannot be loaded into the Cortex if the
firmware version in the Cortex is higher than what easyC was expecting.
The solution is to download the latest version of easyC and then try again.
Also note “connection” problems when downloading programs to the
Cortex can be sometimes be solved by manually selecting the Comm Port
(look at \Tools\Options\Download menu in easyC).