High InTENSity Laser Tag

Inspiration

We figured it would be more fun to play laser tag if you actually felt something when you got tagged, rather than just a buzzer and flashing lights. So we came up with this thing!

What it does

When tagged, the user's vest activates a TENS unit ( Transcutaneous Electronic Nerve Stimulator ).

This connects to the user's abdomen, and stimulates the abdomen muscles to quickly and gently flex. This basically feels like being pushed.

This overall creates a more immersive, fun experience for the players

We made two of these units so two players can duel.

How we built it

We used the following materials:

• YoFit Laser Tag hardware (2x vest, 2x laser blaster)
• 5V DPDT Relay (2x)
• Soldering Iron
• Rosin Core Solder
• Wire Cutters
• Wire Strippers
• Hot Glue Gun
• Hot Glue
• TENS 7000 unit (2x) (2 channels on each unit)

Inside the Laser Tag vests, there are motors used for vibration when the user gets tagged. This motor was removed from a vest and the loose leads were soldered to the relay coil. Next, the two channel wires of one TENS unit were cleaved along the positive side. The two loose ends next to each cut were stripped. Each of the proximal loose ends to the TENS were soldered to each of the common pins of the relay. The distal ends were soldered into the pins of the relay that were normally open. The normally closed pins were left connected to nothing. This setup makes it so that the TENS circuit is closed when the user gets tagged. The relays were glued in the place of the motors, and the vest was sealed.

Next, we decided where to place the TENS electrodes. We decided the abdomen was the best place. This is because stimulation to the legs could cause the user to fall while running, which is unsafe. And stimulation of the arms may cause the user to drop the equipment and cause damage to the equipment or themselves. The abdomen does not play any important role in movement or in holding things, so it seemed like the optimal place for TENS use.

Finally, we had to decide on a fun, user-friendly intensity. Using the internet, we determined the location at which the electrodes should be placed in order to flex the abdominal muscles. We determined that the best location was to connect the two uppermost abdominal muscles to the ground electrodes, and the two positive electrodes to the lowermost abdominal muscles. In order to make sure that the impulse will be captured in the time the relay is closed, we increased the impulse duration to 300 microseconds. We also turned the frequency down to the minimum of 2.0 Hz, because at a lower frequency we will likely only deliver one impulse in the period the relay is open. We do not want the user to feel like they are being tagged multiple times when they are only getting tagged once. Finally, we tested the unit on ourselves to find the minimum intensity at which the muscles significantly flex, while making sure it is relatively comfortable. By doing this, we determined that an intensity level of 4.0 was perfect. By testing on each group member, we determined that the setting was universally comfortable, but also universally visually stimulated everybody's abdominal muscles.

Challenges we ran into

It was difficult to effectively strip all the wires involved, as the strippers we used did not have a small enough gauge. We ended up solving this problem by making small, shallow cuts in the insulated wire and pulling off the insulator by hand. We also ran into the obstacle of the casing being in the way of the TENS wires we connected to the vest. This problem was simply solved by cutting a slit in the vest casing with wire cutters.

Accomplishments that we're proud of

We tested the completed project and everyone had a lot of fun. Seeing our project make people happy was really rewarding.

What we learned

We learned how a TENS unit works, about how DPDT relays work, and about the mechanisms of laser tag hardware.

What's next for High InTENSity Laser Tag

We are considering producing many more of this project so we can play it in large groups with friends. We project that the cost per unit will be between $30 and $40, which is not unreasonable, especially considering just _ one _ round of normal laser tag will run each player about a third of that price. We are looking forward to the future of this project!