Just a litle tweaking :)

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11128527
use warnings;

local $_ = <<END;
 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---.
|                   |                 R |                       |
    .   .---.   .   .   .   .   .   .   .   .   .   .   .---.   .
|       |                                               |       |
    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
|                                           |                   |
    .   .   .   .   .   .   .   .   .   .   .---.   .   .   .   .
|                       |                                       |
    .   .   .   .   .   .---.   .   .   .   .   .   .   .   .---.
|                                                               |
 ---.   .   .   .---.   .   .   .   .   .   .   .   .   .   .   .
|                   |                                           |
    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
|       |                                               |       |
    .---.   .   .   .   .   .---.---.   .---.   .   .---.   .   .
|                           |       |       |                   |
    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
|         *                 |       |                           |
    .   .   .   .   .   .   .---.---.   .   .   .---.   .   .   .
|               |                                 B |           |
    .   .   .   .---.   .---.   .   .   .   .   .   .   .   .---.
|                       |                                       |
 ---.   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
|                                                               |
    .   .   .   .   .   .   .---.   .---.   .   .   .   .   .   .
|                               |   |                           |
    .---.   .   .   .   .   .   .   .   .   .   .   .   .   .   .
|     Y |                                               |       |
    .   .   .   .   .   .   .   .   .   .   .   .   .   .---.   .
|               |                               |               |
    .   .   .---.   .   .   .   .   .   .   .---.   .   .   .   .
|                   | G                                 |       |
 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---.
END

my $starpos = /\*/ && $-[0];
my $base = tr/RGBY*/ /r;
my $w = /\n/ && $-[0];
my $gap = qr/.{$w}/s;
my @queue = code($_) . "= ";
my %seen;
my %before;
my $max = 1025;

sub code { lc(shift) =~ tr/rgby/\0/cr =~ s/\0+/length $&/ger }

while( @queue )
  {
  my ($grid, $moves) = split /=/, shift @queue;
  $seen{$grid}++ and next;
  local $_ = $grid =~ s/\d+/"\0" x $&/ger ^ $base;
  if( 'Y' eq substr $_, $starpos, 1 )
    {
    my $numoves = $moves =~ tr/lrud//;
    print "\n$_\ncompleted in $numoves moves $moves\n";
    exit;
    }
  print "$_=$moves\n";
  for my $robot ( qw( Y G R ) )
    {
    /(?:\| |\w   )\K[ *]([ *]+)$robot/
      && $before{$-[0]}++ < $max
      and push @queue,
      code(s/(?:\| |\w   )\K[ *]([ *]+)$robot/$robot$1 /r)
      . "=$moves ${robot}l";
    /$robot([ *]+)([ *])(?=   \w| \|)/
      && $before{$-[2]}++ < $max
      and push @queue,
      code(s/$robot([ *]+)[ *](?=   \w| \|)/ $1$robot/r)
      . "=$moves ${robot}r";
    /$robot((?:$gap[ *])*$gap)([ *])(?=${gap}-|$gap $gap\w)/
      && $before{$-[2]}++ < $max
      and push @queue,
      code(s/$robot((?:$gap[ *])+$gap)[ *](?=${gap}-|$gap $gap\w)/ $1$
+robot/r)
      . "=$moves ${robot}d";
    /(?:-$gap|\w$gap $gap)\K[ *]((?:$gap[ *])*$gap)$robot/
      && $before{$-[0]}++ < $max
      and push @queue,
      code(s/(?:-$gap|\w$gap $gap)\K[ *]((?:$gap[ *])*$gap)$robot/$rob
+ot$1 /r)
      . "=$moves ${robot}u";
    }
  }
[download]

>   for my $robot ( qw( Y G R ) )

What about "B"? ;)

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

Ah, mucking about with the* and must have put it back wrong :(

But did you have fun? :)

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

Some. I prefer problems that take less run-time though...