How to tilt camera using Olympe for Sphinx

I am new to Olympe SDK. I have searched through the SDK to find how to tilt camera to face the ground while drone is hovering. I have tried the gimbal.set_target but it does not work. What should be the correct interface to tilt the camera?

It seems that gimbal.set_target actually works. I just needed to wait for the camera tilt to finish.