I am making a small two-wheeled robot with Arduino and the shadow chassis. This robot has an arm and I have been thinking of ways to give this robot sight in order to grab objects. Now considering I am relatively new to robotics and my small budget, I cant go into the complicated stuff like using a camera and object detecting software. What i was thinking thus far is that if the robot can move an object it bumps into, then the robot should be able to pick up that object considering its size. To accomplish this I would like to use a pressure sensor. I place the pressure sensor in front of the robot, when the robot bumps into a wall it will simply keep pushing against the wall and the pressure sensor will be triggered continuously, after some x amount of time the robot will stop, back up and choose a new directions to travel. However if the robot bumps into an object and pushes that object, for example, a ball. The sensor will trigger for a moment and then stop as the object will no longer be putting pressure on the sensor. The robot would then stop and activate the arm to come forward and pick up the ball.
Sparkfun has a few pressure sensors and my question is, Which one is appropriate for my task?