For the sake of simplicity, mecha controls can be divided into three category; control jokes, direct trace input and mental control. Often these are mixed and matched with each other to produce a more sensible and maybe even a more plausible way of controlling your giant robot, but in the end all of them are just as bullshit. The level of sophistication that’s gone in the design can always be appreciated, but in the end there’s nothing much else to it.
Joysticks or similar handles are likely the most common form of controls. You can find these from pretty much any Gundam outside G Gundam, in Muv-Luv’s TSFs, Macross and so on. These controls rely on the basic idea of any control jokes, and I’m sure most people have played some sort of flight simulator with a joystick to understand the basic functions. If not, get yourself two joystics, one for each hand, and boot up Descent in dual-stick control mode. That, or pick up Twin-Sticks for Virtual-On for some TSF gameplay.
Gundam Unicorn has a good scene early on, where a Stark Jegan pilot dismisses the computer’s auto-warning system and engages numerous macro options. He then pushes his left control bar forwards in order to boost. This is how most Mobile Suits are controlled in most Gundam series; the keys on the handles work as macro function and option selectors that are directly affecting motion and movement. Additional tweaking, like disabling the auto-warning, is done from the control panel in front. Because the handle bars have no extra hat switch, we can assume that targeting is done by eye-tracking. The image above with Zaku II’s cockpit does seem to have hat switches on them, meaning that they were a thing. Most likely eye-tracking became a standard around the same time as panoramic cockpits hit the scene.
The thing is, controlling a humanoid shape with this sort of controls isn’t effective. While these remind fighter jet controls to an extent, the fact is that massive number of operations are required to be automated. Again, remember that mechas are more akin to an auto shift than manual shift car. Walking is an unconscious act from our part and is essentially controlled falling forwards. If a pilot with these sort of controls would have a direct control of walking, he would need to bend each joint separately to walk. It’s like playing QWOP, but add another dimension to it. In the midst of battle, you don’t have the time to think about center balances and the like, you’re busy trying to keep yourself from the enemy’s crosshair and shoot back.
The joysticks themselves, or controls bars, have two things that you need to keep in mind when designing them; standard human hand dimensions and ergonomics. There was a good research on joystick handles and their sizes, I recommend you to get your hands to it and give a read. Engcon‘s control sticks are an example of industrial sticks that are rather comfortable to the hand and allowed surprisingly large amount of buttons. Of course, you could always model the controls after a real life controls, like the one F-35 has.
Of course, you could go your way out and remove most of the fidelity and go for direct input.
G Gundam’s Mobile Trace system is essentially a four-directional treadmill the pilot stands in. Disregarding how it would actually function, like what happens when the pilot runs forwards or jumps, this system relies on the pilot’s physical skills rather than joystick handling. Depending on the system, the mecha may trace the pilot’s movement 1:1. The pilot’s own instincts and unconscious corrections on moves are directly transferred to the movements of the mecha. While this sort of control method sounds reasonable and even beneficial over the previous one, it has limitations in that it’s still effectively a human body. In Aim for the Top!, Gunbuster has a direct input as well, but it’s more a hybrid between this and the previous control method.
In the .gif above, Noriko is in a half-sitting position rather than standing. While we never see the complete details how she e.g. turns, we can assume that the control strap she is wearing on her back mimics her body’s movements and interprets them to fulfil a pre-determined motion. The hand controls seem to be optional to an extent. This control system changes during the series, where she has a similar but more advanced trace-control system on her, giving e.g. her hands 1:1 control over Gunbuster’s. Human do a lot of controlling with their backs, be it on bike or when driving a car, and if you want your giant robot to have a human like motions, having some sort of connection to it would be a good idea, even if it’s just an exoskeleton that latches to the pilot suit.
Or then just pick up brain signals.
Mental control may be a standard practice in sci-fi, but it’s never that simple. The above example shows that the basic principle of controlling something with just thought is valid, but it takes a lot training and the system is not yet ready. Mapping the brain is a whole other issue altogether, and then you have the individual differences with each and every person’s brains themselves. The basics are the same for sure, but the little details would make this a system that would need more tweaking than the above. The Hex Bug controller shows that he is using an external stimuli to turn the bug around, and that’s something similar we see in e.g. Evangelion. The EVAs are fully controlled with just thought alone, and the handles and triggers they have in the cockpit do jack shit. They’re there to give the idea of shooting and the like, something for the mind to comprehend. Take it this way; rather than thinking of the concept of pulling a trigger and how its done, a pulling a fake trigger sends the necessary data without the pilot needing to overthink the concept or how it’s done.
None of these systems are exceptionally better than the other depending on the fiction you’re aiming for. It’s the style and setting that largely dictates the tone and look of the systems you should go for, and often it might be a good idea to mix these in a some ratio. For example, a joysticks set that extends up to the user’s arms gives an extra dimension of control, as pressured surfaces can sense where the pilot wants the arms or the torso to go. Full Metal Panic uses this sort of mix of both, as does Madox-01 to an almost pornographic degree.
There are as many ways to control a mecha as there are shows, and there are cases where the sense of it all has less impact than the implications and the look. For example, Kouji Kabuto’s Mazingers are essentially controlled with a motorbike handlebar, and this becomes a plot element in Mazinkaiser, when the controller board breaks down, but Kouji jams a muscle bar in its place and beats Dr. Hell’s ass that way. The three described here are essentially starting points, but just as with everything else, it requires a bit of reading how real world analogies work, and I don’t mean just game controllers.