I am 4 years post op from robotic surgery and I have the same problem you are describing and there is nothing you can do but live with it, it will not get better with time. This is a side effect surgeons never tell you about
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I was very lucky when I had my surgery because I was blessed with no ED issues and I was getting a rock solid erection from the day the catheter was removed, and without drugs. The only problem I have is that as soon as I get sexually aroused, I will loose all continence and I will start to drip uncontrolably. I can actually feel my splinkter muscle start to relax when I get aroused. It is really a wierd feeling because I am dry all other times , but as soon I am aroused, I leak like a faucet without any control.
What is even worst is when I have an orgasm. I ejeculate urine with such force, that I can hit the ceiling. What's kind of comical is that I ejeculate urine with more force now , then I ejeculated seman when I had my prostate.
Even if I try to empty my bladder before sex, I will still drip some and ejecualte some urine. I have tried using a condom, but then I loose the sensation and I loose the erection.
The only thing my uro said was that urine is sterile and if you ejeculate into your partner not to worry because it won't hurt her. Just try telling that to a woman. I am thinking about trying to drink white food coloring prior to sex because if I have to ejeculate liquid, at least it would be nice if it looked like seman. 
Through trial and error I found that if you drink a lot of water a few hours before you plan on having sex, and stay a way from coffee and soda, the water dilutes the urine and eliminates the most of the odor. Also when you are ready to have an orgasm, let your partner be on top and that lets gravity help reduce the urine in your orgasm. Other than that, you just have to get use to dripping and get use to putting a lot of towels on the bed.