CharacterParser.php

<?php

class CharacterParser
{
	private $charaters = array(
		'a' => 'ka',
		'b' => 'tu',
		'c' => 'mi',
		'd' => 'te',
		'e' => 'ku',
		'f' => 'lu',
		'g' => 'ji',
		'h' => 'ri',
		'i' => 'ki',
		'j' => 'zu',
		'k' => 'me',
		'l' => 'ta',
		'm' => 'rin',
		'n' => 'to',
		'o' => 'mo',
		'p' => 'no',
		'q' => 'ke',
		'r' => 'shi',
		's' => 'ari',
		't' => 'chi',
		'u' => 'do',
		'v' => 'ru',
		'x' => 'na',
		'w' => 'mei',
		'y' => 'fu',
		'z' => 'ra'
	);

	public function parse($char)
	{
		if(isset($this->charaters[$char]))
			return $this->charaters[$char];
		return ' ';
	}
}

NameParser.php

<?php

class NameParser
{
	private $originalName;
	private $parsedName;

	public function __construct($name)
	{
		$this->originalName = strtolower($name);
	}

	public function parse()
	{
		$name = '';
		$char = new CharacterParser();

		$count = strlen($this->originalName);
		for($i = 0; $i < $count; $i++)
			$name .= $char->parse($this->originalName[$i]);

		$this->parsedName = preg_replace('/\s{2,}/', ' ', trim($name));
	}

	public function getName()
	{
		return $this->parsedName;
	}

	public function __toString()
	{
		return $this->parsedName;
	}
}

soluction.php

<?php

require_once './CharacterParser.php';
require_once './NameParser.php';

if(count($argv) != 2)
{
	echo 'Quantidade de parâmetros inválida.' . PHP_EOL;
	echo 'Ex.: php soluction.php nome' . PHP_EOL;
	echo 'Ex.: php soluction.php "nome sobrenome"' . PHP_EOL;
	exit();
}

$parser = new NameParser($argv[1]);
$parser->parse();
echo $parser->getName() . PHP_EOL;