How would Palpatine have kept Anakin under control?

That's exactly what Anakin wanted to do. He wanted to destroy Palpatine. He told Padme that he was stronger, and that they could rule the galaxy together. But he was too weak minded to do it alone. Vader even tried to get Luke to help him overthrow Palpatine in ESB. Palpatine knew that one day Anakin would turn on him. But I think he knew that he could control him to an extent. Anakin needed information from Palpatine. He needed to learn the ways of the dark side. He knew he was powerful, but he also knew that he needed Palpatine to gain his knowledge. Remember, Anakin thought that Palpatine could help him save Padme from "certain death." Once he had what he needed, I'm sure he would have dispatched Palpatine. But Palpatine knew that too. Palpatine lead Anakin on. After they killed Mace Windu, Palpatine could have easily told Anakin what he needed to know to save Padme, but instead he sent him to destroy the jedi inside the Jedi Temple and then kill the Separatist Leaders. Palpatine needed Anakin to do his dirty work, so he had to lead him on with promises of more knowledge and more power in order to keep him in line. That's the only advantage Palpatine had over Anakin. I hope this answers your question.