$.post传值，Controller那接收不了

//contorller
<?php

namespace App\Http\Controllers\ajax;

use View;
use DB;
use Input;
use App\Http\Controllers\Controller;
use Illuminate\Foundation\Bus\DispatchesJobs;
use Illuminate\Routing\Controller as BaseController;
use Illuminate\Foundation\Validation\ValidatesRequests;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
use Illuminate\Foundation\Auth\Access\AuthorizesResources;

class IndexController extends BaseController
{
use AuthorizesRequests, AuthorizesResources, DispatchesJobs, ValidatesRequests;

public function turnDetail(\Request $request){

if(Request::ajax()) {
$data = Request::input('title');
print_r($data);die;
}

}
}

//js
var turnTitle = $(this).html();

$.post('ajax/turnDetail',{'title':turnTitle},function(data){
console.log('ok');
})

//问题
Request::input('title');
Input::get('title');
Input::all();
都无法读取$.post传递过去的data ＝ ＝
显示500错误

去掉$data = Request::input('title');print_r($data);die;显示ok