|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
| Thread Tools | Rate Thread | Display Modes |
|
#1
|
||||
|
||||
|
battery voltage compensation
I was reading a document describing a specific control loop implementation when i ran across a mention of scaling the output inversely porportional to Battery voltage. When i read this an "AHA" lightbulb went off. This is something that can be implemented extremely easily on a FIRST robot and might be of some use in a few situations:
*any sort of timing based autonomous. Could make much more stable *maintaining optimal tuning of a PID controller during times of low voltage either due to low battery or high motor load. *might have some limited use under driver control. Humans will compensate for decreased sensitivity so it is probably unnecessary in this case. Just an idea i thought i might share with everybody. We already have the voltage info available. It can't hurt. Last edited by Rickertsen2 : 15-10-2005 at 16:01. |
|
#2
|
||||
|
||||
|
Re: battery voltage compensation
Interesting idea.
I dont think battery voltage should matter to your PID loops - they look at what the robot is actually doing and adjust accordingly, so they should respond correctly inspite of the other variables the robot is dealing with (carpet friction, motor temp, obsticals in the way, battery voltage...) but for #1 on your list, if you are running auton open loop, then you could compensate for low battery voltage |
|
#3
|
|||||
|
|||||
|
Re: battery voltage compensation
Jim,
The trouble with this is your controller never knows what the internal resistance of the battery is at any one point in time. (It is a variable that is hard to predict and varies battery to battery.) If the sensors on a device were able to sense voltage rapidly and the load on the battery remained constant, it would be a cool thing to do. On a variable system such as a robot in competition I don't think it would give as good a response as sensors telling the controller how fast/far motors were responding to stimuli. |
|
#4
|
|||
|
|||
|
Re: battery voltage compensation
Quote:
based on the speed of a motor, and whether or not the speed is in the direction of the desired torque, or the direction against it. |
|
#5
|
||||
|
||||
|
Re: battery voltage compensation
Quote:
|
|
#6
|
|||
|
|||
|
Re: battery voltage compensation
Quote:
and your goal is to deliver a torque to bring a rotating object under control, but your means to do that is a pulse width modulated drive to an electric motor. Have a look at the torque/speed curve of a typical electric motor to understand the source of the issue at hand... |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| DC Voltage indicator | Don Wright | General Forum | 5 | 09-09-2005 07:52 |
| Why MUST the 7.2v battery be attached to operate servos on the RC? | Mike Rush | Control System | 17 | 06-02-2004 18:57 |
| RC Circuits | Melissa Nute | Math and Science | 3 | 25-01-2004 05:02 |
| Off-topic battery stuff. | FotoPlasma | Electrical | 4 | 06-01-2003 12:19 |
| Voltage Range of Analog Inputs | Ulibrium | Electrical | 21 | 15-02-2002 14:11 |