Just to amplify on Michael's comment, you will need at least one motor to drive the driving wheels, and one motor (which might be part of an actuator assembly) to turn the steering wheels -- unless you're planning on doing skid-steer. Then you will need more motors to run whatever sort of mechanism you use to pick up the golf balls. So you'll need to decide whether you want to use a claw, or a bucket, or something else. If a bucket, then the bucket will need to tilt up so the ball doesn't roll out, and will need to lift up over the lip of the box, and then tilt down. You might also need a way to trap the balls so they don't just roll away when you attempt to scoop them up with the bucket, unless you're sure you can trap them against something inside the area. Another question would be, if this robot is autonomous, how is it going to recognize a golf ball -- now you're getting into some sort of sensing capability. In order to put all this together, you'll need more hardware of various types. Gears, beams, sprockets, drive belts ... this could be a long list.
As to the motors, the H-bridge would usually be used with the driving motor. Depending on implementation, an H-bridge could also be used for steering, but probably a servo would be a better approach for that. There also stepper motors. The thing is, that, with some exceptions, you will need some sort of driver circuit for each motor. I'm not a roboticist, just thinking in general terms.
I suppose it's possible to pick up a golf ball using some sort of vacuum apparatus too. The coffee ground gripper
would earn you mondo cool points, but I don't know how difficult it is to implement that. Not sure about alternatives to motors -- "muscle wire" could be usable for certain robotic actions -- I don't know whether it's appropriate for your project.
I think that, rather than just doing a search, you might spend some time just reading in the Motors, mechanics, and power
, and the Robotics
forums. Scan titles looking for things that sound relevant, and read a lot. Have you explored the Wiki
yet? Try doing a search for 'golf ball robot' on YouTube.