Getting error in Robot Framework driver (The path to the driver executable must be set by the webdriver.chrome.driver)

i have created java class public class setup {
public void browserSetup() { // System.setProperty("webdriver.chrome.driver","/home/cangouser-38/Documents/mohan/chromedriver"); }

my robot framework test case

* Settings * Documentation A resource file containing the application specific keywords Library Selenium2Library Library com.Auto.Robot.SeleniumRobot.setup

* Test Cases * Check out joe colantonio dot com Open Browser https://www.google.com gc Close Browser

The path to the driver executable must be set by the webdriver.chrome.driver system property; for more information, see https://github.com/SeleniumHQ/selenium/wiki/ChromeDriver. The latest version can be downloaded from http://chromedriver.storage.googleapis.com/index.html