I have a if and else loop.This situation is if the gripper catch something,it will go to somewhere.But the gripper did not catch anything,it will use adjust angle or distance to search for something.I want to know how let UR5 adjust angle or distance when robot know it did not catch anything.THANKS!

By change fixed quantity angle, do you mean you need to test different orientation until you grip the part? You could  use a loop as long as the object isn't detected, make a relative move and try to pick the object again.

Hi,David_Gariepy
Yes,this is my mean.Today,I try it successful.But now I catch something UR can not back to rq_is_object_detected(1).Picture is my program.

@william
You should put a relative move in a loop until the gripper detect something. 
In the following example, if the part isn't detected on the first try, the program will enter in the loop--> open the gripper,  move to waypoint_2 which is a relative move then close the gripper.  It will do so as long as an object isn't detected.  Once an object is detected, it will exit the loop and in this case, halt the program.