Impact velocity measurement. Impact force measurement

Football! Football! The fans are screaming - goal! There have always been serious passions around this game. Millions of boys all over the world have tried and are trying to be like their idols. Football sections and schools never lack people who want to study. The guys try to surpass other players in punch strength and speed. But how can we determine the force of hitting the ball and its flight speed?

Adidas Snapshot to measure impact force: how it works

The pioneer in terms of measuring the force of a ball hit and the speed of its flight was the Adidas company, which introduced the Snapshot program in 2013.

The application was available only to owners of devices based on the iOS platform, but, nevertheless, aroused keen interest among football fans. Subsequently, the development of the program was stopped, as “smart” balls appeared on sale, which, thanks to built-in sensors, measured speed much more accurately.

Using the application is very simple. To do this, you need to calibrate the size of the ball on the monitor. Next, the recording of what is happening begins. The player hits the ball. As soon as the ball stops moving, the recording stops.

It is necessary to mark its initial and final position on the screen. Based on this data, the program measures the distance traveled over a certain time and calculates the speed. This is exactly how footballer Gareth Bale demonstrated it in the commercial.

The program included some pretty interesting features:

However, the development had shortcomings. When Gareth Bale's hitting data became public, many people were able to surpass his results and proved it with their videos. This situation called into question the effectiveness of the work software. This led to the abandonment of the use of video analysis to determine the force of the impact and the speed of the ball.

Other ways to find out the force and speed of an impact

If programs on iOS and Android platforms can still be used for amateur football, then for serious competitions they use equipment of a different class. These include sports radars.

These devices, according to manufacturers, successfully cope with their task. Their development has been going on since 2008. Manufacturers' assurances can be trusted, because for calculations, it is not video recording that is used, but information from sensors that make it much more accurate.

Sports radars on the market are represented by several companies:

SportsSensors.
Supido.
PocketRadar.

The most correct and reasonable solution for calculating the impact force would be to equip the sports equipment itself with sensors. Agree, if there are sensitive sensors inside the ball that immediately at the moment of impact measure its force, and during flight calculate the speed - this is much more productive and accurate. That's exactly what I did Adidas company, when the shortcomings of their mobile program were revealed.

The company released a smart ball, miCoach SMART BALL, which became available for purchase in 2014. However, its price of $300 scared off potential buyers.

Reference! Now the price has dropped to one hundred dollars and has become comparable to the cost of top ball models.

The device has the following characteristics:

classic size five;
twelve sensors;
The battery capacity is sufficient for 2000 ball strikes, and recharging lasts sixty minutes.

Five of the most powerful football kicks

Football history records many strong kicks that hit the target safely. The authors of some of them are listed below.

David Beckham

Back in 1997, the legend of the Manchester United midfield, as well as the England national football team, drove the ball into the Chelsea goal at a speed of 156 km/h. It was so lightning fast that the goalkeeper did not have enough speed to react and intercept the ball.

Cristiano Ronaldo

Cristiano Ronaldo's football career is still far from over, and he already has many individual and club trophies to his name. He has a lot of goals to his name. Like Beckham, Ronaldo specializes in free-kicks. But his most powerful shot came during the game. The ball reached a speed of 185 km/h.

Roberto Carlos

This player from Brazil for a long time retained the title of the football player with the most powerful strike. During the Confederation Cup, he scored a memorable goal against the French team, performed with great force.

From a distance of 35 meters, Carlos took a free kick. He was so strong that the goalkeeper could only follow the ball with his eyes - he simply did not have time to jump.

When honing your fighting skills, you need to track your progress. Of course, it is best to check in gym. But a general idea of physical fitness, speed and impact power can be obtained at home.

Impact speed

Impact speed is no less important than force. After all, even if a person has a huge, “iron” fist, if the blow is slow, there is no point. Speed enhances the punch and helps catch your opponent off guard. A fairly simple exercise will help you find out the speed of impact.

To test you will need a tennis ball. We take it in the non-hitting hand and squeeze it. Then we extend our arm forward. We bring the tested hand to the chin (stand in a stance). Hands should be on the same line. Have a family member or friend count to three. And on the count of three, you open your fist and grab the ball with your other hand as quickly as possible. If the speed is excellent, then you catch the ball on the same line on which it was released. However, it should not fall below 7-10 cm.

Explosive force

Not everyone understands what explosive impact power is. This is how quickly you will reach top speed. A very important indicator, since it determines whether the opponent will fall from the blow or have time to dodge.

To measure, we again take a regular tennis ball. We throw it in the air and immediately hit it with the other hand. Now let's measure:

5-10 meters - Low force.
10-16 meters - Average.
More than 16 meters - High.

In the same way you can train explosive force. And after a while, check the results again.

Total impact power

There is another test. It shows the overall power of the blow. It is often used in training airborne forces. To do this you will need a transparent plastic bag (with handles).

The bag needs to be hung with threads by two handles at chin level. Then you need to stand up and strike in the center. It is very important that the blow does not go down. The goal is to tear the package. If the package just breaks, the blow is not strong enough, there is no good speed, there is no explosive power.

If you pass all three tests, then you have a strong and with a quick blow(like professional fighter). These are excellent indicators.

The sixth year of the third millennium is ending, new generations of athletes are passing into history, but the problem of measuring the force of an impact remains unresolved. Currently, there are many different devices in the world, from cheap and simple to expensive and technically complex, that allow one to measure the force of a blow in martial arts. Moreover, the measurement results of all manufacturers, as a rule, differ significantly, although they all claim to have correct measurements. Amateurs, fans and athletes continue to argue “who has a stronger blow”, do not trust the results of any strength meters (not without reason) and many are already coming to the conclusion that such measurements are not possible at all.

Why does this happen?

The most common sensors used to measure impact force are strain gauges, piezoresistive and piezoelectric force sensors. All of them are highly accurate and are actively used to measure the force of impacts in industry and production, since they were developed for these purposes.
By measuring the impact force using these sensors, we ultimately measure the force generated by the impact and try to interpret it as the desired impact force, which, according to the laws of physics, is determined by the elastic properties of the target and the striking limb, as well as their size, shape and relative speed of movement. Calibration of such meters is possible only for bodies that have the same properties, dimensions and shape, which makes their use in industry possible. In sports, there are no calibrated striking limbs and calibrated blows. Thus, even considering a blow as a collision of two bodies (impact limb and target) with certain properties, shape and mass, we are not able to carry out an unambiguous calibration. The blow is much more complex and lengthy than a simple collision. Therefore, having only the shape of the shock pulse and not having full calibration, it is impossible to obtain correct results when measuring the force and energy of the impact using strain gauges, piezoresistive and piezoelectric force and pressure sensors.

Amusement rides often use spring structures. These designs are only suitable for measuring static forces, in extreme cases, shocks in the way that when hitting such a meter, an opposite elastic force arises (proportional to the amount of compression of the spring), which radically changes the biomechanics of the impact. With a sharp blow, the athlete can easily get injured.
For the same reasons, sensors that use liquid or gas pressure to measure force are not suitable. The biomechanics of the impact is disrupted here due to the elastic buoyancy force that occurs during the impact. Calibration is also not possible for the same reasons.
Thus, the disadvantage of the known solutions is the unreliability of the data obtained, since instead of the impact force, the forces arising during the impact are measured, and according to the laws of physics, they are determined not only by the biomechanics of the impact, as we would like, but also by the elastic properties of the target and the striking limb, and also their sizes and shapes.

I would also like to emphasize that in the absolute majority known cases the designs of the meters greatly change the biomechanics of the kick, which is unacceptable, since it negatively affects the athlete’s punch placement. But even if we choose some ideal target as a target, we do not solve all the problems, since we will still have to “calibrate” the limbs of all athletes, which is impossible. And vice versa, imagining that all limbs are the same, we see that the force of the blow will depend on the rigidity and weight of the target. Even theoretically, the force of a person’s blow on a freely suspended punching bag weighing 8 kg cannot exceed 400 kgf. If you hit a suspended metal ball of the same weight with a metal brass knuckles, you can easily get 4000 kgf. Hence the conclusion: The pursuit of record-breaking blows will only lead to designs of force meters with hard and heavy targets that test your bones for strength and the winner will always be a specialist in breaking stones. Summarize:

It should be recognized that the idea of measuring the force of an impact and taking this parameter as the main characteristic of the impact was initially erroneous and the impact energy should be chosen as the main parameter characterizing the force of the impact. In martial arts the main task and consists in transferring maximum energy to the target during an impact, this determines the effectiveness of the impact. I think the boxers will support us. To ensure that the measurement results are completely unambiguous, we select the kinetic energy of the target after the impact as the measured impact energy. The target, of course, must have physical properties (mass and elasticity) that do not violate the biomechanics of a particular type of strike, and must move freely in the direction of the strike. For boxers, for example, you can take punching bags from famous manufacturers, which will, firstly, eliminate the problem with biomechanics, and secondly, any manufacturer will be absolutely confident in the readings of their device, especially since with a correctly chosen scheme, calibration is not required at all.
I also propose to introduce two additional parameters that not only characterize the force of the blow, but also make it possible to evaluate the quality of the blow and the correctness of its application.
As these two parameters, I propose to choose the maximum force value recorded during the impact (impact) time and the impact (impact) time itself.

Additional parameters, which, although strongly dependent on the physical properties, size and shape of the target and the striking limb, under identical measurement conditions, that is, under the same weight category athletes, with the same type of blow and the same target, will be able to characterize such qualitative characteristics of the blow as sharpness and power. For example, with the same impact energy, a sharper and more powerful impact will naturally be one that has a greater maximum force and a shorter impact time.
By choosing impact energy as the main parameter, we practically eliminate the dependence of the measurement result on the properties, size and shape of the impact limb. More precisely, this dependence becomes an order of magnitude less pronounced.

IN physically this dependence is explained by the fact that part of the impact energy goes to deform the target, and the loss of kinetic energy during an elastic collision of two bodies is determined by the coefficient of recovery, which in turn also depends on the elastic properties of the colliding bodies, on their shape and mass. But the deformation energy relative to the impact energy is insignificant. Of course, the error in measuring weak impacts will be large, but no one is interested in them, since they are considered unsuccessful. As you can see, the measurement accuracy can be easily increased by choosing a rubber impact receiver as a target, which has a recovery coefficient close to unity, but this is more relevant for weak impacts, and for strong ones, the main thing is not to disturb the biomechanics.
I can offer three, in my opinion, noteworthy ways to determine impact energy.
The simplest way to measure impact energy does not require any equipment at all. It is enough to know the school course about kinetic and potential energy, as well as its conservation. To measure target impact energy known mass“m” is mounted on a sufficiently long suspension (for accuracy) and the amount of target deflection after a vertical impact “h” is measured. The energy of the impact will be equal to mgh (g-gravitational acceleration). In this way, it would be possible to measure the impact energy even before our era, and with fairly high accuracy, for example, the impact energy Olympic champion By fist fight the mathematician Pythagoras, who lived more than 2500 years ago, not to mention the boxing champions of the last century and the century before that.

By the way, this rather effective, visual and accurate method can now be used to set Guinness records, which, as a rule, are recorded in a large hall with a wide audience.
For the end of the last century, a method would be suitable for measuring the speed of a target after an impact using a device that uses the Doppler effect during the propagation of ultrasound. If the circuit is correctly selected, calibration is also not required here (Patent registration number 2006130981).
By far the most the best option– use of precision biaxial or triaxial integral accelerometers to measure the energy and force of impacts (Patent Registration Number 2006130906).
The advantage of this method is that strikes at the target can be delivered not in a specific direction, but in any direction, except for strikes from above. Although, using a different design, it is possible to measure the energy of such impacts.

By the way, the impact force (as an additional parameter), unlike the designs known to me, is measured using this method in a really unambiguous and very precise manner (and not in some kind of conventional units, but in kg-s or newtons). But I want to emphasize once again - do not attach much importance to this parameter.
This method allows you not to lose measurement accuracy even in the case of a quick series of strikes, when the target sways and does not have time to take initial position. This allows you to sum up the energy of impacts with high accuracy and correctly assess the physical fitness of athletes. For example, in the mode for determining the physical form of an athlete, a boxing match is simulated with 3 or 12 rounds of three minutes each with a one-minute break. By summing up the energy of blows during a fight, one can easily assess the physical form of an athlete.

Integrated accelerometers with a digital output can be used as accelerometers, the high linearity and sensitivity of which will allow you to do without additional calibration. In the case of choosing accelerometers with an analog output, calibration is also very simple, since during the measurement process g, the acceleration of gravity, is constantly calculated and it becomes possible to organize a self-calibrating system.
Thus, the proposed method solves the problem of reliability of impact force measurements in combat sports. In addition to accuracy, the claimed solution ensures the manufacturability of measurements and resolves the issue of assessing the physical form of an athlete.
Using this method, even in a thousand years we will know “who had the strongest blow,” and not argue about it.

The vast majority of people, even with higher technical education, have a vague idea of what impact force is and what it can depend on. Some believe that the force of a blow is determined by impulse or energy, while others believe that it is pressure. Some people confuse strong blows with impacts leading to injury, while others believe that impact force should be measured in units of pressure. Let's try to clarify this topic.

Impact force, like any other force, is measured in Newtons (N) and kilogram-force (kgf). One Newton is the force due to which a body weighing 1 kg receives an acceleration of 1 m/s 2 . One kgf is the force that imparts an acceleration of 1 g = 9.81 m/s 2 to a body weighing 1 kg (g is the acceleration of gravity). Therefore, 1 kgf = 9.81 N. The weight of a body of mass m is determined by the attractive force P with which it presses on the support: P = mg. If your body mass is 80 kg, then your weight, determined by gravity or attraction, P = 80 kgf. But in common parlance they say “my weight is 80 kg,” and everyone understands everything. Therefore, they often say about the force of an impact that it amounts to some kg, but what is meant is kgf.

The impact force, unlike the force of gravity, is quite short-lived. The shape of the shock pulse (in simple collisions) is bell-shaped and symmetrical. When a person hits a target, the shape of the pulse is not symmetrical - it increases sharply and falls relatively slowly and wave-like. The total duration of the impulse is determined by the mass embedded in the blow, and the rise time of the impulse is determined by the mass of the striking limb. When we talk about impact force, we always mean not the average, but its maximum value during the collision.

Let's throw the glass not too hard at the wall so that it breaks. If it hits the carpet, it may not break. In order for it to break for sure, you need to increase the force of the throw in order to increase the speed of the glass. In the case of the wall, the blow was stronger, since the wall was harder, and therefore the glass broke. As we can see, the force acting on the glass turned out to depend not only on the force of your throw, but also on the rigidity of the place where the glass hit.

So is the blow of a person. We just throw our hand and the part of the body involved in the strike at the target. As studies have shown (see " Physical and mathematical model of impact"), the part of the body involved in the impact has little effect on the force of the impact produced, since its speed is very low, although this mass is significant (reaches half the body weight). But the force of the impact turned out to be proportional to this mass. The conclusion is simple: the force of the impact depends on the mass involved in the impact, only indirectly, since with the help of precisely this mass our striking limb (arm or leg) is accelerated to maximum speeds. Also, do not forget that the impulse and energy imparted to the target upon impact is mainly (50–70%) determined by precisely this mass.

Let's return to the force of impact. The impact force (F) ultimately depends on the mass (m), size (S) and speed (v) of the striking limb, as well as on the mass (M) and stiffness (K) of the target. The basic formula for impact force on an elastic target:

From the formula it is clear that the lighter the target (bag), the less force of impact. For a bag weighing 20 kg compared to a bag of 100 kg, the impact force is reduced by only 10%. But for bags of 6–8 kg, the impact force already drops by 25–30%. It is clear that when we hit a balloon, we will not get any significant value at all.

You will have to basically take the following information on faith.

1. A direct blow is not the most powerful of blows, although it requires good execution technique and especially a sense of distance. Although there are athletes who do not know how to hit with a side kick, as a rule, their direct blow is very strong.

2. The elbow strike is just a little harder. direct blow. And despite its apparent simplicity, it requires its own technique and skill (otherwise it will be weaker than the direct one). Its destructiveness lies in the rigidity of the entire impact structure and surface. By striking a soft bag with an elbow or knee, we will not get significant strength readings, but in battle the same blows on a hard target will be significant in force (and especially in the pressure developed), which can lead to significant injuries.

3. The force of a side blow due to the speed of the striking limb is always higher than that of a direct blow. Moreover, with a delivered blow, this difference reaches 30–50%. Therefore, side punches tend to be the most knockout.

4. A backhand strike (such as a backfist with a turn) is the easiest in terms of execution technique and does not require good physical training, practically the strongest among punches, especially if the striker is in good physical fitness. You just need to understand that its strength is determined by the large contact surface, which is easily achievable on a soft bag, but in real combat for the same reason, when striking on a hard, complex surface, the contact area is greatly reduced, the force of the blow drops sharply, and it turns out to be ineffective. Therefore, in battle it still requires high precision, which is not at all easy to implement.

5. A kick is slightly slower than a side kick, but is still stronger due to the mass and especially the area of the striking limb.

Let us emphasize once again that the blows were considered from a position of strength, and against a soft and large bag, and not in terms of the amount of damage caused.

Projectile gloves reduce impacts by 3–7%.

Gloves used for competition reduce impacts by 15–25%.

As a guide, the results of measuring the force of the delivered blows should be as follows:

Savelyev V.N., 01/15/09, 04/02/09, 12/25/15