ActiveBot Test for Trim

ziyad101

When running the Active Bot with Test for Trim after the calibration. The system goes in circles one way and then starts a circle in another way.. Is there some calibration steps I need to follow with the potentiometer ?

Andy Lindsay (Parallax)

This usually means that there is still a mistake in your circuit or mechanical assembly.

Check what you have done against these pages with careful attention to detail.

http://learn.parallax.com/activitybot/electrical-connections
http://learn.parallax.com/activitybot/mechanical-assembly

After you have found the next problem, re-run the calibration. If it goes straight with Test for Trim after that, then good. If it still behaves erratically, it means there is still another mistake.

ziyad101

Andy, I had taken the whole module apart and reassembled it.. It seems that one wheel is moving at a faster rate than the other wheel. I will look through and see if there is data in the Interpolation table as well. Where I am going with this is maybe I have to tweak the potentiometer in the servo that is moving really really fast ? thoughts ?

Andy Lindsay (Parallax)

The next step is to post your calibration table results. You can copy and past it from SimpleIDE to a reply post here. Make sure to use the tag [noparse]

before what you paste in and

after.[/noparse] Here is a link to an example of what your interpolation table should resemble. http://forums.parallax.com/showthread.php/155275-ActivityBot-Robot-Issues?p=1261046&viewfull=1#post1261046

The rightmost column should start at 1000, then jump down to something in the 170 to 205 range. After oscillating for a few entries, it should decline to zero, then increase back up to where it started. This pattern should be roughly the same for both left and right wheels. If it's not, it's likely that you still have a wiring or assembly error. When you post the interpolation table, we'll have a better idea of what that error might be.

Publison

Could also be a problem as explained in this thread:

http://forums.parallax.com/showthread.php/150281-Activity-Bot-mechanical-assembly-step-7-amp-8-heads-up?p=1207655#post1207655

ziyad101

My encoders are all the up by the edge of the wheels

not like the good one shown in http://forums.parallax.com/showthrea...55#post1207655 .. Is there a way to push the encoders down so that they see the spokes like the one that is depicted in the Good picture

Publison

ziyad101 wrote: »

My encoders are all the up by the edge of the wheels

not like the good one shown in http://forums.parallax.com/showthrea...55#post1207655 .. Is there a way to push the encoders down so that they see the spokes like the one that is depicted in the Good picture

You want the encoders up as far as possible to see the spokes.

Try this to reset the servos:

http://learn.parallax.com/activitybot/troubleshooting

Phil Pilgrim (PhiPi)

Based upon your last post, ziyad101, I wonder if you've mounted the servos or encoders backwards. That's the only way I can think of for the sensing area to be "too high" relative to the spokes. To clarify, the servo shaft should be directly below the encoder's sensing area, not off to one side.

-Phil

ziyad101

I believe I set up the servos and encoders the right way. I am also attaching pictures as well..

ziyad101

I have included the pictures of the left side with the wheel mounted and without the wheel mounted. All the wiring seems to be correct. I have gone in as per Andy's instructions and have taken all the connections off first and then rewired again. It seems that the sensors are way above the spokes.

Phil Pilgrim (PhiPi)

ziyad101 wrote:

I believe I set up the servos and encoders the right way.

Um, no. As I suspected, your servos are mounted backwards. The shaft should be towards the rear, not the front.

That said, however, if you plan to mount a heavy load to the front of the bot, such as a gripper, you will want to reverse the encoder instead, so that the cable protrudes forward. But in most cases, having the servo shaft rearward is the better option.

-Phil

ziyad101

thanks Phil, I never thought to go down that path.. Makes sense, I will reverse the servo shafts and check it out

ziyad101

ok , swapping the direction of the shaft of the motors did it. It now passes the encoder test and also did a successful calibration. However when I go to use the Test trim code, the Bot makes about 4-5 turns on the spoke. Any ideas on where to go from here ?

Andy Lindsay (Parallax)

Regarding "...the Bot makes about 4-5 turns on the spoke." It's difficult to tell what you mean here. Could you try explaining again?

If the test program doesn't take the ActivityBot slowly forward for eight seconds, there may still be another assembly step that was not followed correctly. For example, maybe the resistors are the wrong values, something other than 20 k = red-black-orange. Or maybe the supply jumper for the P12/P13 headers was not set to Vin. Or maybe the cable that's supposed to be connected to P12 is connected to P13 and vice-versa. Or maybe it's the P14 and P15 cables that are swapped. Those are some examples of common assembly errors, but yours may be different.

Some of the common errors and their symptoms are documented here: http://learn.parallax.com/activitybot/troubleshooting

Sometimes we can get hints about what's wrong if you post your ActivityBot's calibration table. Please see post #4 http://forums.parallax.com/showthread.php/156153-ActiveBot-Test-for-Trim?p=1276281&viewfull=1#post1276281 in this thread.

ziyad101

=== LEFT SERVO === 

 Table Entries = 89
 Zero Speed Index = 44
 

 Index   Servo Drive     Encoder Ticks/Second
 -----   -----------     --------------------
 0       -194            1000
 1       -189            178
 2       -184            180
 3       -179            182
 4       -174            178
 5       -169            184
 6       -164            178
 7       -159            178
 8       -154            182
 9       -149            178
 10      -144            180
 11      -139            178
 12      -134            175
 13      -129            175
 14      -124            173
 15      -119            177
 16      -114            173
 17      -109            169
 18      -104            171
 19      -99             167
 20      -94             167
 21      -89             162
 22      -84             159
 23      -79             154
 24      -74             148
 25      -69             148
 26      -64             138
 27      -59             135
 28      -54             123
 29      -49             117
 30      -44             113
 31      -39             100
 32      -34             94
 33      -29             89
 34      -24             78
 35      -19             67
 36      -14             57
 37      -9              48
 38      -4              39
 39      1               28
 40      6               19
 41      8               15
 42      10              10
 43      12              7
 44      19              0
 45      26              7
 46      28              11
 47      30              15
 48      32              19
 49      34              22
 50      39              31
 51      44              44
 52      49              49
 53      54              59
 54      59              67
 55      64              78
 56      69              85
 57      74              92
 58      79              103
 59      84              109
 60      89              116
 61      94              123
 62      99              131
 63      104             139
 64      109             144
 65      114             146
 66      119             150
 67      124             156
 68      129             161
 69      134             159
 70      139             163
 71      144             165
 72      149             166
 73      154             170
 74      159             170
 75      164             174
 76      169             172
 77      174             172
 78      179             174
 79      184             176
 80      189             178
 81      194             178
 82      199             179
 83      204             178
 84      184             176
 85      189             178
 86      194             178
 87      199             179
 88      204             1000
 

 

 === RIGHT SERVO ===
 

 Table Entries = 88
 Zero Speed Index = 34
 

 Index   Servo Drive     Encoder Ticks/Second
 -----   -----------     --------------------
 0       -195            1000
 1       -190            172
 2       -185            167
 3       -180            170
 4       -175            163
 5       -170            165
 6       -165            165
 7       -160            161
 8       -155            165
 9       -150            158
 10      -145            160
 11      -140            150
 12      -135            153
 13      -130            140
 14      -125            145
 15      -120            135
 16      -115            138
 17      -110            124
 18      -105            122
 19      -100            111
 20      -95             107
 21      -90             104
 22      -85             91
 23      -80             83
 24      -75             76
 25      -70             66
 26      -65             57
 27      -60             47
 28      -55             40
 29      -50             31
 30      -45             26
 31      -40             16
 32      -38             11
 33      -36             6
 34      -29             0
 35      -22             3
 36      -20             9
 37      -18             13
 38      -16             16
 39      -14             21
 40      -9              31
 41      -4              39
 42      1               47
 43      6               58
 44      11              66
 45      16              74
 46      21              82
 47      26              92
 48      31              98
 49      36              106
 50      41              116
 51      46              126
 52      51              127
 53      56              132
 54      61              137
 55      66              146
 56      71              147
 57      76              150
 58      81              153
 59      86              158
 60      91              158
 61      96              165
 62      101             163
 63      106             165
 64      111             166
 65      116             167
 66      121             168
 67      126             166
 68      131             174
 69      136             172
 70      141             176
 71      146             174
 72      151             172
 73      156             176
 74      161             172
 75      166             178
 76      171             174
 77      176             172
 78      181             176
 79      186             172
 80      191             174
 81      196             172
 82      201             172
 83      181             176
 84      186             172
 85      191             174
 86      196             172
 87      201             1000

ziyad101

The system after calibration during Test for trim only goes through 4-5 ticks

Andy Lindsay (Parallax)

Your calibration data looks good, so don't change any wiring or mechanical things.

If you are going to load code to make the ActivityBot navigate, make sure to:

(1) Plug the battery supply in
(2) Set the PWR switch to 1
(3) Use the Load EEPROM & Run button to load the code into the bot
(4) Set the power switch to 0 while you take it to the place where it's going to navigate
(5) Set the PWR switch to 2
(6) Set the bot down and observe

If it just twitches forward by a few spokes repeatedly, it may mean the batteries are dead. If the Activity Board was left on over night, the LED lights may have brought the batteries down. If one of the batteries is trying to fall out of the pack, it can also have those symptoms.

One other thing to check would be to make sure the shunt jumpers next to the P12/13 and P14/15 servo ports are fitting tightly over their pins. The P12/13 shunt should be over VIN and the center pin, and the P14/15 jumper should be over the 5V and center pin. If either of them are not fitting tightly, pull the shunt jumper off and bend the pins very slightly apart so that when you put the shunt jumper back on, it'll fit snuggly.

Andy Lindsay (Parallax)

One other thing, if you put one of the batteries back in backwards, you'll also see the twitch forward a few spokes symptom.

Courtney Jacobs

Please be sure to make sure there is absolutely no power connected to the board if you see a need to adjust the shunt jumpers.

Unplug the barrel jack and USB cable connection fully before moving any shunt jumper, or you will damage your board.

ziyad101

Hi Andy,
wanted to provide feedback. I got it finally working with the trim code. Now I can go forward /backwards, right and left.. The issue I ran into and not sure why, the copy of the trim program that I downloaded was faulty. I downloaded the example code and copied and pasted from the learn zip folder that I downloaded again. and that seemed to do the trick