Serious problem about AcitivityBot .

Jarvan · 2013-11-17 22:38

After we assembled more than 50 ActivityBot , we find more than one third have problem , one third have same but intermittent problem, We Checked the hardware assemblely as the turtorial carefully, But we can not find the reason and a effectly solution. Is there something wrong with the turtorial on the web? It really make me crazy!!

Jessica Uelmen · 2013-11-17 23:05

Hi Jarvan,

Are you still having issues with the encoders? Will they not calibrate? What behaviors are you seeing?

Jessica

Ken Gracey · 2013-11-18 09:03

Jarvan,

We should probably check to see that your encoders are working properly. As designed, the two calibration programs don't make it very easy to debug an encoder problem.

Load this code:

#include "simpletools.h"


int main()
{
  low(26);
  low(27);
 
  while(1)
  {
    set_output(26, input(14));
    set_output(27, input(15));
  }  
}

Download to EEPROM, turn the wheels gently on your ActivityBot. Do you see the LEDs on P26 and P27 illuminate? If so, then you should be able to run the calibration programs. If not, then there's no encoder signal - check for misalignment of the encoders to the wheels.

Report back and we'll continue to debug this problem. We may not hear from you until late today because it's about 1 am in China, so we'll check back this evening.

Ken Gracey

Publison · 2013-11-18 09:16

Don't know if this post would help:

http://forums.parallax.com/showthread.php/150281-Activity-Bot-mechanical-assembly-step-7-amp-8-heads-up

Jim

Ken Gracey · 2013-11-18 10:15

Jarvan, even more importantly see this thread:

http://forums.parallax.com/showthread.php/151633-Need-help-Re-calibration-of-ActivityBot-failed

Steph Lindsay · 2013-11-18 16:09

Hello Jarvan,

I have updated the Electrical Connections page with a picture to help identify left and right sides of the robot, for cable connections. I also added a Connection Checklist to the bottom of the page.
http://learn.parallax.com/activitybot/electrical-connections

The code that Ken Gracey put in the third post is very helpful! There are other tips on the ActivityBot Troubleshooting page:
http://learn.parallax.com/activitybot/troubleshooting

I hope this helps!

-Stephanie

Steph Lindsay · 2013-11-18 18:25

And, I have just added a page to the tutorial: Test the Encoder Connections:

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

Jarvan · 2013-11-18 21:13

After we adjust the positon of the encoder, I think the encoder work well now, but we meet the problem again. I use the following code to test the pairs of encoders:

#include "simpletools.h"
#include "abdrive.h"
 
int main()                    
{
  int valueR,lastseenR;
  int valueL,lastseenL;
  int mL;int mR;
  lastseenR=1;
  valueR=0;
  lastseenL=1;
  valueL=0;
while(1)
{
  mL=input(14);
  mR=input(15);
   
if(mL==1)
  {
    if(lastseenL==1)
    {
      valueL++;
      lastseenL=0;
      print("valueL=%d  ",valueL);
    }
  }
    else
    {
      lastseenL=1;
    } 


  if(mR==1)
  {
    if(lastseenR==1)
      {  
      valueR++;
      lastseenR=0;
      print("valueR=%d\n",valueR);
      }
  }
  else
  {
    lastseenR=1;
  }
 
 }
}

then I push the robot on the ground to make it go straight for a distance, the terminal shows as following:

the encoders seem work well. but after I calibration them, It's hard for them to run a program accuratly.

such as I code a program to make the robot have a 90 degrees turn, it always turn too much and then slowly turn back to 90 degrees.

Jessica Uelmen · 2013-11-19 15:56

Hi Jarvan,

By how much does the robot overshoot the target? 10 degrees, 20, 45? If it is a small twitch that's normal behavior. The way the encoder program works is that is counts the total number of ticks from the robot and compares it to the number of ticks the robot should take based on code. If it finds it went too far, it will reverse to the proper count. If you can upload a video of the operation, that might help us visualize the problem.

We should also check your calibration values, which could help diagnose the issue. Could you run the Activity Bot Display Calibration program (found in the Navigation folder on your computer, or attached to this thread)? Be sure to run with terminal, and copy the values displayed in this window to this thread. Once we see those values we should be able to get a better idea of what's going on.

Jessica

Jarvan · 2013-11-20 01:37

I adjusted the servo position, I think some problem may as follow pictures:

After I mounted the ActivityBot as the turtotial on the web , I am sure the process is all right, but i am not sure whether the ActivityBot can work well, I have to upload some codes to test the encoders.

And , before you help us find the encoder problem, my colleague and I try to use screwdriver to adjust the servo, make it stop running. It must be stupid behaviour and I don't know what effect it will cause.

When I am ready to take a video about it, make it have a 90 degrees turn, it suddenly be a lamb and do everything accurately once and again. I give up and turn off camera , show it to my colleague , It suddenly and suddenly have a almost 360 degrees turn and slowly turn back to 90 degrees.

At last, the display of calibration data as following:

=== LEFT SERVO ===

Table Entries = 89
Zero Speed Index = 25

Index Servo Drive Encoder Ticks/Second

0 -194 1000
1 -189 146
2 -184 142
3 -179 144
4 -174 138
5 -169 138
6 -164 129
7 -159 128
8 -154 120
9 -149 113
10 -144 111
11 -139 101
12 -134 94
13 -129 86
14 -124 75
15 -119 67
16 -114 59
17 -109 52
18 -104 43
19 -99 33
20 -94 25
21 -89 19
22 -87 16
23 -85 11
24 -83 7
25 -76 0
26 -69 6
27 -67 10
28 -65 14
29 -63 16
30 -61 20
31 -59 25
32 -54 35
33 -49 42
34 -44 52
35 -39 60
36 -34 67
37 -29 74
38 -24 82
39 -19 90
40 -14 94
41 -9 105
42 -4 108
43 1 114
44 6 119
45 11 123
46 16 128
47 21 132
48 26 134
49 31 140
50 36 140
51 41 144
52 46 140
53 51 145
54 56 144
55 61 151
56 66 145
57 71 151
58 76 148
59 81 154
60 86 152
61 91 154
62 96 152
63 101 154
64 106 151
65 111 155
66 116 152
67 121 154
68 126 152
69 131 154
70 136 149
71 141 157
72 146 151
73 151 157
74 156 149
75 161 154
76 166 148
77 171 157
78 176 152
79 181 157
80 186 150
81 191 155
82 196 150
83 201 155
84 181 157
85 186 150
86 191 155
87 196 150
88 201 1000

=== RIGHT SERVO ===

Table Entries = 89
Zero Speed Index = 42

Index Servo Drive Encoder Ticks/Second

0 -195 1000
1 -190 145
2 -185 150
3 -180 138
4 -175 152
5 -170 147
6 -165 153
7 -160 143
8 -155 150
9 -150 143
10 -145 149
11 -140 146
12 -135 144
13 -130 142
14 -125 139
15 -120 143
16 -115 141
17 -110 139
18 -105 135
19 -100 137
20 -95 125
21 -90 129
22 -85 118
23 -80 121
24 -75 114
25 -70 106
26 -65 106
27 -60 100
28 -55 95
29 -50 86
30 -45 83
31 -40 69
32 -35 68
33 -30 68
34 -25 57
35 -20 44
36 -15 37
37 -10 31
38 -5 21
39 0 14
40 2 10
41 4 6
42 12 0
43 20 6
44 22 13
45 24 17
46 26 20
47 28 25
48 33 38
49 38 47
50 43 57
51 48 68
52 53 73
53 58 82
54 63 92
55 68 98
56 73 107
57 78 113
58 83 116
59 88 119
60 93 125
61 98 125
62 103 133
63 108 132
64 113 137
65 118 136
66 123 139
67 128 139
68 133 140
69 138 142
70 143 143
71 148 143
72 153 142
73 158 151
74 163 92
75 168 98
76 173 114
77 178 111
78 183 119
79 188 108
80 193 117
81 198 116
82 203 113
83 178 111
84 183 119
85 188 108
86 193 117
87 198 116
88 203 1000

Jessica Uelmen · 2013-11-20 10:18

What is the battery voltage for the robot? Based on the calibration values, it looks like the batteries may be worn out. I'm not seeing a speed value higher than 150, and with fresh batteries you should reach 190-200. Low battery voltage might explain some of the strange behaviour, too (working, then not working).

Depending on how much you adjusted the potentiometer, that may have had an effect. Especially if you centered them after calibration. The calibration depends on a center pulse around 1.52 ms, and if you've deviated too far from that point, there will be issues. Looking at the calibration data, it seems the left may be the only one with an problem. I'd re-center the left servo with the following program.

[FONT=courier new]/* Center Signal Left Servo.c[/FONT][FONT=arial][FONT=Courier New][/FONT] [/FONT]
[FONT=arial][FONT=Courier New]   Center signal to ActivityBot's left servo (closer[/FONT][/FONT]
[FONT=arial][FONT=Courier New]   to servo ports).  [/FONT][FONT=Courier New]This code can be adjusted for[/FONT][/FONT]
[FONT=arial][FONT=Courier New]   the right servo (closer to PWR switch) by [/FONT][/FONT]
[FONT=arial][FONT=Courier New]   changing servo_set(12, 1500) to [/FONT][FONT=Courier New]servo_set(13, 1500).[/FONT][/FONT]
[FONT=arial][FONT=Courier New]*/[/FONT][/FONT]
[FONT=arial][FONT=courier new,monospace][/FONT] [/FONT]
[FONT=arial][FONT=courier new,monospace]#include "simpletools.h"    // Include simple tools
#include "servo.h"          // Include servo[/FONT][/FONT]
[FONT=arial][FONT=courier new,monospace]int main()                  // main function
{
  servo_set(12, 1500);      // Left servo center signal
[/FONT][/FONT]
[FONT=courier new]}[/FONT]

Then, with fresh batteries, re-run the calibration. It's important that any time you make any mechanical modifications to the robot that the calibration is rerun.

Serious problem about AcitivityBot .

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