convert collection to array of strings

I'm trying to export a quiry result in Laravel 5 to excel it gives me the error Object of class stdClass could not be converted to string when i use the code below it works

$equipements=Equipement::all();
    $equipements=collect($equipements)->toArray();
    Excel::create('Inventaire',function($excel) use ($equipements){
        $excel->sheet('Page 1',function ($sheet) use($equipements){
            $sheet->fromArray($equipements);
        });
    })->export('xlsx');

but that's not the result i want, i want to specify fields from different tables, is there any way to convert a collection to array of strings the method collection->torray return array of objects that's not what i want.

via Chebli Mohamed