Vex 393 Motor Upgrade White Paper

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2 Νοε 2013 (πριν από 3 χρόνια και 5 μήνες)

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Vex 393 Motor Upgrade White Paper

The Problem

The current

motors
(
2
-
Wire Motor 269
)
provided
in

Vex

standard kits
have plastic gears that eventually break even when using
protective
clutches.

This causes a lot long repair times as motors tend to be deeply rooted in side the robot even more time if heavily
geared for operation.

The Proof

Many
,

if not all
,

teams can attest to having had issue
s

with these
plastic geared
motors
.

Even in

the
lower torqued higher speed
electric
RC car market only
the
cheapest

base model cars still use plastic gearing.

Basic Solution

This problem is easily remedied by allowing t
he use of the metal geared

electric motors. Clutches
,

all though still recommended,
may
not be needed at all in some applications where the only risk is the damage of the gears with in the motor.

Our Proposition

We propose allowing the use of

the

Vex metal geared motors
(
2
-
Wire Motor 393
)
to
help alleviate repair
times between
as well as
increasing motor performance to the robots as a hole. E
ven
though the locked rotor c
urrent value

of 4.8 amps is

over the 2.6 amp value
of the older plastic geared version.

We feel if vex allows this increase in current then
they must feel it poses

no

significant risk to the robot. That is as long as the
presc
ribed usage is adhered to.

Possible issues


Improper usage could lead to motor port or even micro controller current overload shutdown.

The 2
-
Wire Motor 393 does not have an internal motor controller.

The motor
can connect

directly to 2
-
Wire Motor Ports (Ports 1 & 10 on the Cortex Microcontroller). For 3
-
Wire Motor Ports (Ports 2
-
9 on
the Cortex), a
Motor

Controller

29

must be used in between the Microcontroller and the motor.

Note should

be taken
that

the collective current handling capability of the Micro controller
is only 4 amps on IO 1
-
5 and 4 amps on 6
-
10

Critical
Parts Specifications

2
-
Wire Motor 269



Free Speed:100 rpm



Stall Torque:8.6 in
-
lbs



Stall Current:2.6A



Free Current:0.18A

2
-
Wire Motor 393



Free Speed:100 rpm (As Shipped)/160 rpm (High Speed Option)



Stall Torque:1.67 N
-
m (14.76 in
-
lbs) (As Shipped)/1.04 N
-
m (9.2 in
-
lbs) (High Speed Option)



Stall Current:4.8A



Free Current:0
.37A