I agree with the critique that the metal should be more... colorful. But I'm thinking rather than blindly changing colors for the metal, you should take the flower color into account. Metal reflects a lot, so you should see the colors from the flow in the shades of the metal. So you should bend the metal shades towards red.
Here's an edit with a palette adjustment and adding in some tiny reflection of the flower to your robot:
Basically, the dark spots become a slightly saturated purplish, but it should be relatively grey, and then as you go up the ramp, the colors should become less and less saturated. Experiment with a bunch colors for yourself! It's fun once you get the hang of it.
Cool robot at any rate! Keep up the good work.
Might look better with a bit of anti-aliasing for the shades next to the outlines too. And shade in the flower petals and detail the stem a bit!
EDIT: Oh, and now I realized you weren't looking for critique on this sort of stuff yet. :/