There's no getting away from it: unless you're a robot, and/or you have a semi dysfunctional relationship with your daughter, the father of the bride speech is going to be emotional, and so it should be...in parts. As I've written many times before, the best antidote to becming a blubbering wreck, is to have plenty of funny lines and ideas scattered throughout the speech, and they will act as the perfect balance for some of the more meaningful things you'll hopefully be saying. However, on the day when the emotions are running high, and it becomes very apparent that this is a huge turning point in all your lives, any normal person will be fighting back the tears.
Everyone enjoys seeing a little emotion in speeches, it shows you're real, this matters, and how devoted you are to your daughter, however, there is a limt. Once the waterworks start, it can rapidly take over, and soon all the guests will be able to hear are some gargled mumblings, as your lungs fight to stave off the torrents of tears. So, how do you mitigate this, and avoid disaster on the day? Easy. Practice.
The best way to cope with the emotion is to practice the speech so much, that the big messages you're getting across, the memories and the sentiment, will all feel so familiar that you will have become immune to their effect. If you've ever tried to watch a comedy stand up routine on consective nights, you'll understand the process. The first evening it's hilarious, the second evening, not so much. If you can get to know that speech inside out, then when you deliver the more sentimental parts, you'll be able to carefully pick your way through them, as if you're the most calm and collected person in the world. It's a very basic trick, but like most simple solutions, it's easily the most effective.
