LabVIEW is "software". To control a liquid, you need "hardware". Some hardware (like the faucet on a typical sink) has no easy way to be controlled by software, whether LabVIEW or Excel or Visual Basic. Other hardware, however, can accept (usually electrical) "signals" that can be generated under computer control (i.e. by software).
Similarly, software cannot "know" much about the external world (except if it waits for the User to type something in through a "Standard Input" device), but needs one or more "sensors" that look at something in the external world and translate pressure, light, sound, voltage, etc. into an electrical signal in a form that can be read by a computer, i.e. "more hardware".
Fortunately, you don't need "hardware" to get started on your software development -- you can simulate the hardware by using Software. Take your problem -- "modifying a shape by injecting a liquid".
- How will you control the liquid injection? Will it be "On/off" (like a light switch) or "proportional" (like a faucet)? Does it have aspects of both? (Most faucets, for example, only allow liquids to flow out, not in, so you'd say the flow can't be negative).
- What criteria do you want to use to start the flow of the liquid? What will you be monitoring? How will you know how much flow to use (which gets back to is the flow on/off or can it take different values)?
- What criteria will you use to stop the flow?
If the flow is on/off, a Boolean (True/False, On/Off) variable can model the Flow Control. Otherwise, a Dial/Knob can work. LabVIEW has looping controls (While Loop, For Loop) that can model processes that vary over time (like "flow"), and even have Timing Functions that you can use to slow the code down so that it actually simulates "real time".
Get a pencil and a piece of paper and draw out how you might design a simple flow system. [Computer Scientists often call this paper design a "Flow Diagram"!]. Once you think you know what you want to do, see if you can translate it into simple LabVIEW.
Once you have this working, you can think about how to move this to the "real world", thinking about the "sensors" that inform you about the status of the Real World and the "actuators" that alter the Real World.
Bob Schor
