What supply voltage does the rest of your robot run on? What is that circuit supposed to do in your application? Looks like it just amplifies/buffers the voltage set by VR1, and VR2 biases the inverting input.
If your robot has a single supply of say, 5V, use a rail-to-rail op-amp (the 741 is an ancient, poor performing part by today's standards). If you need a floating ground reference for the op-amp, just use two resistors to form a voltage divider.
Knowing what you need the circuit to do will help us design it better.
And in reference to the original post, voltage is always relative, measured across two points. For example, take BobK's two 9V batteries wired in series. Assuming the batteries are fresh and actually putting out 9V, you can get measurements of +9V, -9V, +18V, or -18V depending on which points you're measuring relative to each other. "Ground" in a circuit is typically the point considered to be 0V for the circuit, and is the common return for most/all of the circuits within. For example, when working with a digital IC, or a 555 timer for that matter, and you're measuring the voltage at the output, you typically measure between that output and "ground".
Most circuits that use a single supply voltage (not a split rail) will use the "-" side of the battery or power supply circuit as the circuit ground, and all voltages in the circuit are positive relative to ground. But that isn't absolutely required. You could have the + side be ground, and have your voltages be negative, if the circuit is designed appropriately. Some older cars have a positive ground electrical system, for example, though negative ground is far more common and all newer cars use a "negative" ground (that just means the - terminal of the battery is tied to ground).
In the case of an op-amp that runs on a "split" supply, you don't absolutely have to use a split supply. You can get by with a single supply as long as you supply a virtual "split" with a voltage divider so that the op-amp is working at the middle of its range, since most op-amps can't work with voltages approaching the rails. For example, if your circuit is running off a 12V battery, a voltage divider could bias the op-amp's inputs at 6V, and if the op-amp can handle voltage up to 1V of either rail, the op-amp can handle inputs and outputs between 1V and 11V relative to the 12V supply, or -5V to +5V relative to the voltage divider's "ground". Circuits using older ops like the 741 always used +/- 15V supplies (for a total supply voltage of 30V) because the 741 can only get within ~1.5-2V of either rail, so to work with a +/-12V signal you need a +/-15V supply. Modern "rail to rail" op-amps can get closer to the rails so they're more suitable for the lower single-supply circuits of today.