If you need a mini controller for your robot, This product will be your type. We have developed a product called Grove - Mini Track ball. As you can see, on this product, there is a mini track ball here, you can feel free to rotate the ball horizontally and vertically from any angle. There are 5 axes here, up down left right and press down. As you move the ball, you will get the the values from these 5 axes and the values will be changed according to the direction and speed you move the ball.
With the STM32F103C8T6 and AN48841B chip inside, you can turn plenty of your ideas into real things. It is also standardized with Grove interface which will save you a lot of work in the process of prototyping.
Have fun !