Thanks for the link. Unfortunately, my wife would divorce me if I dropped $4500 on one of these machines. I am not in the arcade business so it would be a pretty hard purchase to justify. I did try the game, and really liked the concept though. I figured it would make a cool DIY project, and would be fun to bring out at family reunions, team parties etc. if I could put something together that would read reliably enough to foster some friendly competition. I've seen lots of examples of stationary targets that are usually used by martial artists for measuring the force of their punches, but they seemed more geared toward the serious athlete than the casual game-player. The Boxer machine with its speed bag mechanism was just more "fun". Maybe as Bean suggested earlier in this thread I will need to dispense with the force, acceleration sensors altogether, and instead mount a couple optical sensors on the frame. When the arm (chain) of the bag passes the first optical sensor it will initiate the start timer, and when it passes the second sensor it will send a stop signal. By getting the elapsed time between sensor one and sensor two tripping, and factoring in the distance between the two sensors, I should be able to get a reliable reading of how fast the bag is moving. I could calculate an arbitrary "force" from there and have it stay consistent between punches. With the sensors mounted in the frame, I could have all the circuitry wired together without the worry of having it break apart from impact. My only question is how far away an optical sensor can be from the object it is measuring and still get a reliable reading. Any input/comments or the pointing out of any potential flaws in this system would be welcome. :P
bannor32,
Unfortunately, physics may once again foil your idea. With you proposed setup, unless the lever was rigid, there is a big chance that the movement of the chain will not accurately reflect the force of the impact. Ignoring any variation in the direction of the strike (a lower strike moving slightly upward could conceivably change the pivot point from the top of the chain to something lower), a martial artist could strike the bag and cause it to hit your "top" platform and come down without ever deflecting the chain at all (I exaggerate to make a point).
the other one makes some VERY valid points on constructing for durability. I also did my time in the family entertainment business and you probably could not imagine the abuse these machines take.
It appears that a linearly actuated sensor OR a combination of registering the speed of the fist (optical?) and instantaneous acceleration of the bag (accelerometer?) would probably give you the most indicative readings.
This is an interesting one.
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Truly Understand the Fundamentals and the Path will be so much easier...
If you were leaning more towards a "speed bag" type of game....then the bag would be banging off the board behind it.
You could use a force sensor there or even a hall effect sensor (put the magnet in the bag....put a couple magnets in the bag); you could use an opto beam that gets broken when the bag interrupts it. THis would be fun for, "who can get the bag going the fastest"...and you might be able to fool around with some math and use how many beam breaks per second to determine the force (someone else can say if hte math is right).
Does it have to be "real world" accurate...no...it's a game...it just has to show that 1 person was better than the other! haha
But gorilla's they are...and I certainly remember the big bins of spare parts we had at the arcade! Caught a guy trying to steal the fake 'sea-doo' off of the "Wave runner" game! lol
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Steve http://ca.geocities.com/steve.brady@rogers.com/index.html "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
If I can't manage to work out the speed bag problem, I may end up going another direction. I found this punching bag called a Century Bob at a local sporting goods store. Here is a link to Bob:
His plastisol body has quite a bit more give than a standard heavy bag. I figure I could put padded boxing headgear over its head, and maybe try the flexiforce between the headpad and the Century Bob. With the softer impact surface it would allow people to hit it as hard as they could with minimal risk of injury. Also, the ability to hit a 'human' opponent would give it more of a fun factor. Having a stationary target with a force sensor should allow me to get more consistent readings.
If everything works well I might end up adding multiple sensors down the road for extra strike points, allowing for an interactive game that not only registers a punch, but how hard the punch was...
How about a bag that is held firmly in place by two bungee cords, one attaching it to the ceiling, the other attaching it to the floor. Find an electronic spring scale that would calculate the force at either the ceiling or the floor, there would be a static force that holds the bag in place that would have to be subtracted out. You could also adapt a mechanical spring scale which has a cut through slot for the force indicator and mount a series of LEDs and photodiodes in this slot to detect the position of the indicator. A fair amount of energy will be placed into the bungee's elasticity, but seeing as how you do not care what the actual force is, this shouldn't matter. Here's a crude drawing to show what I mean:
____________ ceiling
|
| bungee
|
O bag
|
| bungee
|
------------ floor
Paul...they're called dodge'em/weave'em balls...or double-end striking ball.
Boxers use them to hit and then dodge them on the way back! http://www.karate-mart.com/blacdoubstri.html
I like the novelty idea of hitting a real person (am I a sadist...no comment! lol).
You could put in different "strike areas".· Hey, if you want to work on 'advanced' jui-jitsu techniques and have them aim for pressure points....just wire up the pressure point with a hall affect sensor and put the magnet in a glove.·
In martial arts, they don't always hit full force, so just being able to hit hte spot is good training (although it's funny to wail away!).
To be honest....you don't need to measure the full force of the impact.· If some guy can throw a 200lb bomb...you don't need a sensor that would stand up to a 200lb hit.· Just put the sensor deeper in the mass of the object hit....then you'll just have to calibrate your readings to what the actually represent.
Seriously though, go with 'Beat'em Up Bob'!!· You could make modular faces and let ppl make some of their boss! OK..I am a sadist!
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Steve http://ca.geocities.com/steve.brady@rogers.com/index.html "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Comments
Post Edited (bannor32) : 4/9/2005 6:35:02 PM GMT
Unfortunately, physics may once again foil your idea. With you proposed setup, unless the lever was rigid, there is a big chance that the movement of the chain will not accurately reflect the force of the impact. Ignoring any variation in the direction of the strike (a lower strike moving slightly upward could conceivably change the pivot point from the top of the chain to something lower), a martial artist could strike the bag and cause it to hit your "top" platform and come down without ever deflecting the chain at all (I exaggerate to make a point).
the other one makes some VERY valid points on constructing for durability. I also did my time in the family entertainment business and you probably could not imagine the abuse these machines take.
It appears that a linearly actuated sensor OR a combination of registering the speed of the fist (optical?) and instantaneous acceleration of the bag (accelerometer?) would probably give you the most indicative readings.
This is an interesting one.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Truly Understand the Fundamentals and the Path will be so much easier...
You could use a force sensor there or even a hall effect sensor (put the magnet in the bag....put a couple magnets in the bag); you could use an opto beam that gets broken when the bag interrupts it. THis would be fun for, "who can get the bag going the fastest"...and you might be able to fool around with some math and use how many beam breaks per second to determine the force (someone else can say if hte math is right).
Does it have to be "real world" accurate...no...it's a game...it just has to show that 1 person was better than the other! haha
But gorilla's they are...and I certainly remember the big bins of spare parts we had at the arcade! Caught a guy trying to steal the fake 'sea-doo' off of the "Wave runner" game! lol
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·
Steve
http://ca.geocities.com/steve.brady@rogers.com/index.html
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
http://martialmart.com/bodopbagbob.html
His plastisol body has quite a bit more give than a standard heavy bag. I figure I could put padded boxing headgear over its head, and maybe try the flexiforce between the headpad and the Century Bob. With the softer impact surface it would allow people to hit it as hard as they could with minimal risk of injury. Also, the ability to hit a 'human' opponent would give it more of a fun factor. Having a stationary target with a force sensor should allow me to get more consistent readings.
If everything works well I might end up adding multiple sensors down the road for extra strike points, allowing for an interactive game that not only registers a punch, but how hard the punch was...
____________ ceiling | | bungee | O bag | | bungee | ------------ floorIm thinking of a sensor like this http://www.vernier.com/probes/probes.html?dfs-bta&template=standard.html
Post Edited (Paul Baker) : 4/11/2005 6:41:26 PM GMT
Boxers use them to hit and then dodge them on the way back!
http://www.karate-mart.com/blacdoubstri.html
I like the novelty idea of hitting a real person (am I a sadist...no comment! lol).
You could put in different "strike areas".· Hey, if you want to work on 'advanced' jui-jitsu techniques and have them aim for pressure points....just wire up the pressure point with a hall affect sensor and put the magnet in a glove.·
In martial arts, they don't always hit full force, so just being able to hit hte spot is good training (although it's funny to wail away!).
To be honest....you don't need to measure the full force of the impact.· If some guy can throw a 200lb bomb...you don't need a sensor that would stand up to a 200lb hit.· Just put the sensor deeper in the mass of the object hit....then you'll just have to calibrate your readings to what the actually represent.
Seriously though, go with 'Beat'em Up Bob'!!· You could make modular faces and let ppl make some of their boss! OK..I am a sadist!
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·
Steve
http://ca.geocities.com/steve.brady@rogers.com/index.html
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."