Activitybot questions

Brubacher

I just got my Activitybot today and I put I to gather like how the tutorial said to but the Test and tune program only makes the left servo move. what is going on. also there are parts in the tutorial that says to turn the power switch to 0 then turn the power to two an the program will start.but my bot clears the program when I do that. is this normal or are the guides wrong or do I have a defective board?

RDL2004

I don't have an Activitybot, but maybe this will help.

the Test and tune program only makes the left servo move.

This could be a wiring problem. Check all your connections as described here:

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

the tutorial that says to turn the power switch to 0 then turn the power to two an the program will start.but my bot clears the program when I do that.

Make sure when you load the program that you use load to eeprom, not to RAM. If it's loaded to RAM it will be erased when power is turned off.

Good luck, and welcome to the forum.

Andy Lindsay (Parallax)

Moving to Learn forum.

Andy Lindsay (Parallax)

I agree with RDL2004, go through and double-check all your electrical connections carefully, following the instructions in these pages:

http://learn.parallax.com/activitybot/electrical-connections
http://learn.parallax.com/activitybot/test-encoder-connections

After that, go back through the Calibration Activity, and follow the instructions very carefully. Especially make sure that you allow the calibration to complete by waiting till the yellow lights turn off.

If the symptom persists, repeat the Try This section of http://learn.parallax.com/activitybot/calibrate-your-activitybot, and post your output to this thread. A healthy interpolation table should resemble this (below). The numbers do not have to match exactly. Focus in the third column. Ignoring the 1000 values, the rest should start in the 170 to 200 range, decline to 0, and then back up to the 170 to 200 range. It should work this way for both right and left servos.

=== LEFT SERVO ===

Table Entries = 89
Zero Speed Index = 41

Index   Servo Drive     Encoder Ticks/Second
-----   -----------     --------------------
0       -194            1000
1       -189            170
2       -184            170
3       -179            170
4       -174            188
5       -169            181
6       -164            172
7       -159            170
8       -154            172
9       -149            168
10      -144            172
11      -139            172
12      -134            170
13      -129            168
14      -124            159
15      -119            164
16      -114            162
17      -109            159
18      -104            154
19      -99             150
20      -94             146
21      -89             145
22      -84             139
23      -79             132
24      -74             130
25      -69             124
26      -64             115
27      -59             106
28      -54             97
29      -49             89
30      -44             82
31      -39             71
32      -34             65
33      -29             56
34      -24             45
35      -19             36
36      -14             27
37      -9              19
38      -7              14
39      -5              10
40      -3              6
41      4               0
42      11              2
43      13              8
44      15              11
45      17              14
46      19              16
47      21              22
48      26              33
49      31              43
50      36              50
51      41              59
52      46              67
53      51              80
54      56              86
55      61              93
56      66              98
57      71              109
58      76              113
59      81              122
60      86              125
61      91              135
62      96              140
63      101             143
64      106             149
65      111             150
66      116             149
67      121             162
68      126             153
69      131             157
70      136             159
71      141             164
72      146             160
73      151             162
74      156             168
75      161             170
76      166             164
77      171             176
78      176             164
79      181             168
80      186             168
81      191             172
82      196             170
83      201             170
84      181             168
85      186             168
86      191             172
87      196             170
88      201             1000


=== RIGHT SERVO ===

Table Entries = 89
Zero Speed Index = 40

Index   Servo Drive     Encoder Ticks/Second
-----   -----------     --------------------
0       -195            1000
1       -190            174
2       -185            170
3       -180            176
4       -175            172
5       -170            172
6       -165            170
7       -160            172
8       -155            174
9       -150            170
10      -145            166
11      -140            166
12      -135            166
13      -130            163
14      -125            159
15      -120            157
16      -115            148
17      -110            154
18      -105            156
19      -100            145
20      -95             142
21      -90             140
22      -85             133
23      -80             121
24      -75             121
25      -70             110
26      -65             104
27      -60             97
28      -55             88
29      -50             80
30      -45             72
31      -40             68
32      -35             56
33      -30             45
34      -25             37
35      -20             28
36      -15             19
37      -13             19
38      -11             11
39      -9              8
40      -1              0
41      7               6
42      9               7
43      11              14
44      13              14
45      15              21
46      20              31
47      25              41
48      30              45
49      35              58
50      40              66
51      45              76
52      50              82
53      55              91
54      60              99
55      65              105
56      70              114
57      75              120
58      80              121
59      85              134
60      90              137
61      95              140
62      100             148
63      105             157
64      110             156
65      115             159
66      120             172
67      125             164
68      130             168
69      135             174
70      140             164
71      145             168
72      150             166
73      155             170
74      160             170
75      165             172
76      170             170
77      175             172
78      180             172
79      185             176
80      190             176
81      195             166
82      200             168
83      175             172
84      180             172
85      185             176
86      190             176
87      195             166
88      200             1000

Leo Bots

I've run into a problem with strange servo behavior. While running "Detect and Turn from Obstacle" I noticed the servos were not following the speed commands in the program. I re-ran the Calibration and Calibration Display programs and everything seems normal. I also checked the battery pack voltage and it's reading 6.6v. into a 2.2Kohm load. When I tried running the "Open Speeds for Navigation" program the AB moved exactly as the drive_speed commands told it to, but it would not stop! The Propeller board kept recycling or looping through the program until I turned the power off. After several experiments what I discovered was that the servos will follow the drive_speed and drive_ramp commands exactly as long as the speed is not set above 72 tps or below -72 tps. I wrote a very simple program that includes both simple tools and abdrive. The main function is
{
drive_speed(64, 64);
pause(2000);
drive_speed(0, 0)
}
The AB runs at 64 tps for 2 seconds and stops. But, if you raise the speeds to say 78 and 78 it will loop through the main function until the batteries drain out. I have no idea what's causing this.

Andy Lindsay (Parallax)

Your batteries do sound a little tired. Nominal voltage should be 7.5 V with brand new batteries of certain brands coming as high as 8.25 V. So the first thing I'd like to rule out would be power resets as a result of increased current draw the servos take to make sudden direction changes. It might be dropping the supply voltage more than we'd expect. So, try a fresh set of alkaline batteries, and let's see what happens.

Leo Bots

Thanks, Andy. It must have been auto-resetting because of low battery voltage. I replaced the batteries and the AB seems to be working fine now. I remember this being a problem with the old BOE Bot too. I was surprised though to find the AB servo circuit was sensitive to what was only a 0.8 v. drop as they are operating at 5.0v! It looks like at 6.7 volts the batteries can't supply enough current to the servos to allow them to run at speeds above 72 tps . Yet, with each of the old batteries putting out a average of 1.3 v. your throwing away a lot o good battery power. I'll have to see if I can find another use for these.

Andy Lindsay (Parallax)

Hmm, it seems like the batteries should be able to go lower than that. Is your P12 P13 supply shunt (to the left of the P12, P13 servo ports) jumper set to VIN or 5 V? It should be set to VIN.