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Read all the width as reported by the laser #8

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Read all the width as reported by the laser #8

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adec8c8
Read all the width as reported by the laser
Nov 20, 2013
0564a05
Remove unnecessary name in comment.
tulku Feb 17, 2014
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7 changes: 6 additions & 1 deletion hokuyo/src/main/java/com/github/rosjava/rosjava_extras/hokuyo/LaserScanPublisher.java
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Original file line number Diff line number Diff line change
Expand Up @@ -105,11 +105,16 @@ sensor_msgs.LaserScan toLaserScanMessage(String laserFrame, LaserScan scan,
"Number of scans in configuration does not match received range measurements (%d > %d).",
numberOfConfiguredRanges, scan.getRanges().length));
float[] ranges = new float[numberOfConfiguredRanges];
int scannedRanges = scan.getRanges().length;
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Why is this change necessary? Is numberOfConfiguredRanges computed incorrectly?

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This will avoid painful debugging and unnecessary crashes in favor of a clear warning message if, for any unanticipated reason, numberOfConfigured ranges doesn't match scan.getRanges().length - as it happened to us when trying to use this code.

The reason numberOfConfiguredRanges could be different than scan.getRanges().length is because the former is calculated at configuration time (FF command) but the number of ranges on each scan can technically be different for each distance acquisition request (MD).

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In that case, just set numberOfConfiguredRanges = scan.getRanges().length.

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Hmm ... are you sure about that? In most cases both should match. A mismatch between them might indicate a higher-level logic error. I think this will end up being a useful check, it does provide additional information about what's going on to the programmer. And in most circumstances, both numbers should match anyway, particularly with the change below

for (int i = 0; i < numberOfConfiguredRanges; i++) {
int step = i + configuration.getFirstStep();
// Select only the configured range measurements and convert from
// millimeters to meters.
ranges[i] = (float) (scan.getRanges()[step] / 1000.0);
if(step>=scannedRanges) {
ranges[i] = 0;
} else {
ranges[i] = (float) (scan.getRanges()[step] / 1000.0);
}
}
result.setRanges(ranges);
result.setTimeIncrement(configuration.getTimeIncrement());
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7 changes: 5 additions & 2 deletions hokuyo/src/main/java/com/github/rosjava/rosjava_extras/hokuyo/scip20/Device.java
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Expand Up @@ -117,6 +117,8 @@ private void waitUntilReady() {
boolean ready = false;
while (!ready) {
ready = true;
// NOTE(Julian Cerruti) At this moment, the sent command does not matter much.
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Please use your username in NOTEs and TODOs. In this case though, I think you can just write a comment. No one needs to track you down to understand the motivation here.

// Currently fixed to (0; 768)
write("MD0000076800001");
try {
checkMdmsStatus();
Expand Down Expand Up @@ -260,8 +262,9 @@ public void startScanning(final LaserScanListener listener) {
@Override
public void run() {
while (true) {
String command = "MD00000768000%02d";
write(String.format(command, 99));
String command = String.format("MD%04d%04d000%02d", configuration.getFirstStep(),
configuration.getLastStep(), 99);
write(command);
checkMdmsStatus();
checkTerminator();
String scansRemaining = "99";
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