Chief Delphi - Help with custom circuts

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Help with custom circuts

Wanted to know if it was legal to use a switch to directly cut voltage to the arm servo motor when it reaches its mechanical limit???

Re: Help with custom circuts

I would say no per rule <R83>. Emphasis mine.

Quote:

<R83> All outputs from sensors, custom circuits and additional electronics shall connect to other custom circuits or the Robot Controller. If connected to the Robot Controller, they must connect through the analog inputs, digital I/O, TTL Serial Port, or Program Port only. Custom circuits must not connect to the Robot Controller through any other ports. Custom circuit outputs shall not be connected to speed controllers, relay modules, pneumatic valves, servos, motors, or actuators.

EDIT: <R53> also appears to prohibit this.

Quote:

<R53> Custom circuits shall NOT directly alter the power pathways between the battery, fuse
blocks, speed controllers, relays, motors, or other elements of the robot control system
(including the power pathways to other sensors or circuits). Custom high impedance voltage
monitoring or low impedance current monitoring circuitry connected to the ROBOT’S
electrical system is acceptable, because the effect on the ROBOT outputs should be
inconsequential.

The same effect should be achievable by connecting the limit switch to the RC and implementing the cutoff in software.

Re: Help with custom circuts

Ok, here is the custom circuit exactly.

ASCII Art included
................................................{l imit Switch}.................
.................................................. ......||.........................
................................. ______[>]___[Spike]___..................
................................/..................................\............... .
.. _________{}=====<................................. ....>---{CIM}-|
..|......._____...............\_______[<]__[Spike]___/................|
..|.......|......|................................ .......||........................|
-+---(-)-.....|.................................{limit switch}...............|
| BATT..|....|______________________________________ ___|
|______|.......................................... ...................................

[>] are diodes
The limit switches are triggered by the movement of swinging arms and the overall purpose of the circuit is to stop unwanted momentum swinging by a large four bar arm system. I.e. once reaching its lower extent the limit switch throws one of the relays and prevents the flow of current in the direction that the motor wishes to travel, therefore reducing the "hammer" effect of the arm.

Re: Help with custom circuts

The rule that Vikesrock quoted is about as explicit as you can get...you cannot do that.

Connect the limit switches to the digital inputs on the Robot Controller, and use software to make them control the relay outputs.

Re: Help with custom circuts

Again, I believe that this alters the power pathways between components (prohibited by <R53>) as well as connects the output of a custom circuit to a relay, motor or both (prohibited per <R83>).

Is there any reason you cannot connect the switches to the RC and shut off the relay when the switch is triggered using software?

Re: Help with custom circuts

Nearly every part of the posted custom circuit breaks a rule. Here's another one you're going to want to pay attention to and fix immediately:

Quote:

Originally Posted by <R62>

...Each CIM motor and Fisher-Price motors must be connected to one Victor speed controller. They must not be connected to relay modules...

Re: Help with custom circuts

Iceman,
In addition to all the great advice above (Nice catch Alan on the CIM motor in the diagram above) you will not find any limit switches capable of handling the immense current that is a stalled CIM motor (133 amps). The rules are written to protect against things like this.

BTW, even if allowed, the diode in the bottom branch circuit will not conduct even if the relay pulled in. It will remain reverse biased since the anode is at a lower voltage than the cathode.

Re: Help with custom circuts

if you do the direct voltage cutting (even though, as stated many times above is illegal), if you directly cut voltage, and a part is at it's maximum, you can't reverse the motor to move it again, as all voltage is cut off.