A microcontroller-based system might be simplest (at least in terms of hardware), but here's a conceptual panning solution doing things the analogue way :-
View attachment 99260
You would need to duplicate that circuit for the tilt control.
As you can see, it ain't trivial
.
Here's how the PWM-controlled motor current (and hence speed) would vary as the joystick pot is moved from its neutral (spring-centred) position to either extreme:-
View attachment 99261
Circuit explanation:
I have assumed the PanPot is a 10kΩ one with a wiper which can move over a range of 0.4 to 0.6 of the pot value.
U1 is a hex CMOS inverter IC, U2 is a quad opamp IC. The simulated motor has a 3Ω coil resistance and 4mH inductance (your mileage will vary).
U2a gives an output which varies in proportion to the PanPot wiper displacement from the central position. U2b amplifies this output.
U1c/U1d/R4/R7 form a Schmitt trigger which, with R8 and C3, makes an oscillator of ~1kHz. The pulse width of the oscillations is controlled by a voltage obtained by weighting the output
d of U2b, using Trim1 a Trim2 as summing resistors, to give a PWM output
f.
U2c is configured as a classic square-wave oscillator and drives a voltage doubler to give a ~24V output
h.
U1a, U1b, with a small amount of positive feedback via R1, provide complementary direction signals
b and
c according to which side of centre the Panpot wiper is displaced. These signals switch level-shifters Q1, Q2 which are high-side drivers for N-FETs M1, M3 of an H-bridge M1-M4. The direction signals also enable/disable (via diodes D5 andD6) the PWM signal
f which drives the low-side N-FETs M2, M4 via buffers U1e, U1f. Although these CMOS buffers can provide only limited current they should be able to cope, in view of the low PWM frequency and consequent very low duty cycle; but if in doubt they could be replaced by push-pull BJT buffers.
Here's the asc file if anyone wants to play: