ActivityBot mobility issue

metalRabbit

My friend and I are working together on an Activity Bot. He handled the circuitry and I'm handling the C language for what we eventually want to do. I'm having a problem with this little thing where the left wheel does not want to move forward. This is the simple code used to test the wheels:

#include "simpletools.h"#include "abdrive.h"             


int main()
{
  drive_goto(16,16);
  return 0;
}

This makes the right wheel move forward as expected, but not the left. When the parameters are changed to (-16,16) the left wheel moves backwards while the right moves forward. Every other combination where the left wheel is supposed to be moving forward doesn't seem to work. I've tried running the tutorials for the Activity Bot, and the problem seems to persist. I really just want to know if there's anything I can do programming-wise, before blaming the hardware or circuitry. >_<

metalRabbit

Addendum: We checked the motor in question and it works just fine. So after that I tried reversing the ports for the servo pins, and then set the robot to run backwards. It'll now run forward this way, but it won't go backwards with both wheels. So it can move forward but the problem is still there.

Phil Pilgrim (PhiPi)

Try recalibrating the robot. Make sure your batteries are fresh before doing so.

-Phil

Courtney Jacobs

metal,

If you try recalibrating and are still having issues, could you post the output from your calibration table here for us to see? That might help us find the problem.

metalRabbit

I ran the calibration, and it functioned properly. I still have the problem running my own code though. All 4 batteries tested at about 1.44 volts, so I don't think that's the issue.

This is the output on the console after running ActivityBot Display Calibration:

=== LEFT SERVO ===

Table Entries = 67
Zero Speed Index = 1


Index   Servo Drive     Encoder Ticks/Second
-----   -----------     --------------------
0       0               1000
1       0               0
2       0               0
3       0               0
4       0               0
5       0               0
6       0               0
7       0               0
8       0               0
9       0               0
10      0               0
11      0               0
12      -160496444              0
13      1580372         0
14      524290          0
15      111415495               0
16      661627068               0
17      637819988               0
18      661612796               0
19      571497596               0
20      1081596         0
21      -1341095684             0
22      1671420         0
23      439484416               0
24      126091264               0
25      65535           0
26      0               0
27      0               0
28      705757184               0
29      739606780               0
30      739191036               0
31      1409276         0
32      10443900                0
33      12278908                0
34      8543356         0
35      15228028                0
36      16211068                0
37      9723004         0
38      11689084                0
39      16604284                0
40      1474812         0
41      1662076         0
42      6904956         0
43      7167100         0
44      6511740         0
45      6773884         0
46      7953532         0
47      1662076         0
48      5790844         0
49      570491068               0
50      570491068               0
51      705768700               0
52      705724668               0
53      570491068               0
54      806628604               0
55      806709436               0
56      806444156               0
57      772899068               0
58      772309244               0
59      26812           0
60      1596668         0
61      570491068               0
62      805830844               0
63      570517692               0
64      571432060               0
65      -580494212              0
66      -1387963268             1000




=== RIGHT SERVO ===


Table Entries = 199
Zero Speed Index = 49


Index   Servo Drive     Encoder Ticks/Second
-----   -----------     --------------------
0       -195            1000
1       -193            59
2       -191            61
3       -189            63
4       -187            65
5       -185            67
6       -183            -1275068347
7       -181            491520016
8       -179            531800
9       -177            -1992327168
10      -175            569389612
11      -173            461500
12      -171            654315004
13      -169            1640508
14      -167            537135292
15      -165            537135292
16      -163            537135295
17      -161            23676
18      -159            0
19      -157            -65536
20      -155            0
21      -153            0
22      -151            0
23      -149            570491068
24      -147            704946364
25      -145            706765052
26      -143            3169340
27      -141            11885692
28      -139            14507132
29      -137            8805500
30      -135            15817852
31      -133            9395324
32      -131            9985148
33      -129            11820156
34      -127            741497980
35      -125            1662012
36      -123            6380668
37      -121            7429244
38      -119            7691388
39      -117            6642812
40      -115            8019068
41      -113            8150140
42      -111            5921916
43      -109            806444156
44      -107            772899068
45      -105            772309244
46      -103            570491068
47      -101            672214268
48      -99             672694524
49      5               806840508
50      109             26812
51      111             570491068
52      113             570491068
53      115             806825212
54      117             -1606263684
55      119             638671996
56      121             806453500
57      123             639118588
58      125             24936700
59      127             1679548
60      129             1662206
61      131             1662206
62      133             1662206
63      135             570491068
64      137             1662206
65      139             570491068
66      141             1662206
67      143             570491068
68      145             1662206
69      147             504454396
70      149             1679548
71      151             1655266557
72      153             806444156
73      155             0
74      157             0
75      159             0
76      161             0
77      163             0
78      165             0
79      167             0
80      169             0
81      171             0
82      173             0
83      175             0
84      177             0
85      179             0
86      181             0
87      183             0
88      185             0
89      187             0
90      189             0
91      191             0
92      193             0
93      195             0
94      197             0
95      199             0
96      99              0
97      -1              0
98      1               0
99      3               0
100     5               0
101     7               0
102     9               0
103     11              0
104     13              0
105     15              0
106     17              0
107     19              0
108     21              0
109     23              0
110     25              0
111     27              0
112     29              0
113     31              0
114     33              0
115     35              0
116     37              0
117     39              0
118     41              0
119     43              0
120     0               0
121     0               0
122     0               0
123     199             0
124     0               0
125     67              0
126     1000            0
127     59              0
128     61              0
129     63              0
130     65              0
131     67              0
132     -1275068347             -160496444
133     491520016               1580372
134     531800          524290
135     -1992327168             111415495
136     569389612               661627068
137     461500          637819988
138     654315004               661612796
139     1640508         571497596
140     537135292               1081596
141     537135292               -1341095684
142     537135295               1671420
143     23676           439484416
144     0               126091264
145     -65536          65535
146     0               0
147     0               0
148     0               705757184
149     570491068               739606780
150     704946364               739191036
151     706765052               1409276
152     3169340         10443900
153     11885692                12278908
154     14507132                8543356
155     8805500         15228028
156     15817852                16211068
157     9395324         9723004
158     9985148         11689084
159     11820156                16604284
160     741497980               1474812
161     1662012         1662076
162     6380668         6904956
163     7429244         7167100
164     7691388         6511740
165     6642812         6773884
166     8019068         7953532
167     8150140         1662076
168     5921916         5790844
169     806444156               570491068
170     772899068               570491068
171     772309244               705768700
172     570491068               705724668
173     672214268               570491068
174     672694524               806628604
175     806840508               806709436
176     26812           806444156
177     570491068               772899068
178     570491068               772309244
179     806825212               26812
180     -1606263684             1596668
181     638671996               570491068
182     806453500               805830844
183     639118588               570517692
184     24936700                571432060
185     1679548         -580494212
186     1662206         -1387963268
187     1662206         -984064900
188     1662206         638671996
189     570491068               1092124924
190     1662206         638671996
191     570491068               1226998012
192     1662206         638671996
193     570491068               1529184508
194     1662206         -1370399620
195     504454396               572039356
196     1679548         1655266428
197     1655266557              1662205
198     806444156               1000

Phil Pilgrim (PhiPi)

Those are not good calibration values. Are you sure you have the motors and encoders connected properly? Did you remember to add the 10K pullups to the encoder lines?

-Phil

Andy Lindsay (Parallax)

From the looks of your interpolation table, there's a wiring mistake. I would recommend going very carefully through these two pages a second time:

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

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

Notes: Make sure to stick with the 20 k pullups called for in the Electrical Connections page. Here is an example of what your interpolation table should resemble when the electrical connections are correct. Although this table is showing top speeds in the 170 ticks/second range, yours will vary with battery voltage. Top speeds in the 170 to 200 range are typical.

=== 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

RickInTexas

I had similar symptoms, calibration seemed to go OK -- spun around CW, CCW, pause, rinse, repeat etc. Then I came across

Issue: The ActivityBot calibration routine went fine, but instead of driving straight, it drives in a jerky, wavy line.

which is on page: http://learn.parallax.com/activitybot/troubleshooting about 3/4 the way down. Fixxed my ActivityBot.