It’s a “game board” with a movable piece on top. As the piece moves around, the board lights up beneath it, in some defined color and radius. I figured I would detect the location of the piece via some analog Hall effect sensors mounted in the corners of the board. Four sensors in the corner should be able to pinpoint the location of a magnet in the base of the playing piece.
But what if there were two game pieces? What if there were many pieces in two teams? Is there a way for Hall effect sensors to determine which magnet is which? I know there are Hall sensors that can read both a magnet’s polarity and strength, so that should solve the problem, but I’m wondering if there’s a better way? Maybe magnets and Hall sensors aren’t the right way to go for a project like this? Is there a better way to detect the position of lightweight playing pieces?
Thanks for any help or brainstorming you can provide.
FWIW, I don’t actually have a game design in mind yet. This is just a proof of concept for the technology. I’ll design the toy or game around it some time later.
Reading polarity and strength from a hall sensor (or 4 at the corners) would not be enough to reconstruct the position of multiple pieces with magnets. You’ll have a very hard time reconstructing the magnetic fieldlines on such a board. The more you’ll have on the board, the more complicated it gets. Maybe with hall sensors arranged in a grid in the plane, sensing the field lines from the nearest pieces you’ll have more luck. But pieces near eachother can still hide one another.
What you haven’t explained is if the pieces are constrained to a grid. Or can their positions be anywhere? If it is constrained to a regular grid, then you could place small reed-switches under those positions and read those like a keyboard matrix. Or research how the really old magnetic core memories worked:
lyndon:
How are you going to determine which piece belongs to which team?
Great question. I know that there are hall sensors that can read the magnet's polarity, so I figured one "team" would be N and the other would be S.
But if hall sensors and magnets aren’t the way to go, I’ll also have to think of a way not just for the sensors to detect the inputs. but also distinguish between sets of inputs.
Valen:
What you haven’t explained is if the pieces are constrained to a grid. Or can their positions be anywhere?
I had hoped this would be an analog system, where the pieces could be anywhere on the field. I’ve never played with Hall effect sensors, so I may have been seriously overestimating the resolution they’d provide. At any rate, thanks for the link to the magnetic core information, and for your thoughts overall. Much appreciated.
I should probably define a little better my thinking about this project. I’ve started envisioning where I might want to go with it: Imagine a board, maybe 12" x 12", with miniature characters on it as the playing pieces (think miniatures war games or D&D miniature figures). Players could engage in battles by casting spells, either on their own characters (as protections), on their opponents, or onto the battlefield. It would bridge the arenas of computer gaming and real world tabletop gaming.
As I type that, it occurs to me that there is a precedent for this. I know there are iPad-based games that have real-world components that players manipulate on the tablet surface to interact with game elements. So that’s based on the capacitive screen of the iPad and some kind of capacitive element within the game pieces. Something like that might be worth investigating.
