Kicking mechanisms of soccer robots

In this article we’re going to talk about what kinds systems are used in soccer robot kicking mechanism and how they work.

Robots are one of the wonders of our modern world. Every year many robots are created to make our life a bit easier. But one of the fascinating thing about robots is that they can also play soccer! 

You may have watched many soccer match and hoping that your favorite team will win. But watching robots playing soccer is another joy. But if you’re interested in how these robots actually kick during the robot soccer competitions, keep reading.

What is the kicking mechanism of a soccer robot?

Every robot should have an actuator in order to move. Actuator is a system which let wheeled robots to move around and let legged robots to bend their joints. Since a soccer playing robot needs to kick like a human in order to play soccer, there should be a special actuator to make this happen.

Actuator Systems In Soccer Robots

So there are three actuator systems in a soccer playing robot, one of which is the kicking system. The two other systems are movement system, and dribbler system.

The movement system must perform the movements according to the commands which come from the processor, and the dribbling system must always keep the ball in front of the robot.

A robot kicker must kick the ball like a real player in order to start and play a game. In a real soccer match it is the leg which kicks the ball, but in a robot, kicking a ball is not that simple. In robot playing soccer, the kicking system kicks the ball as soon as a specific control command comes from processor of robot. This is exactly the soccer robot kicking mechanism.

Each team designs its own kicking mechanism but in general they can be divided into 3 main categories.

• Robot Springs
• Pneumatic Systems
• Solenoids Systems

Spring mechanism

The first mechanism is related to the robot springs. Robot springs which has the simplest mechanism is based on the mechanical potential energy stored in a spring. The mechanism of robot springs is so simple: A spring is compressed, held, and released at certain times.

Like any other mechanisms, this one has its own pros and cons as well. Talking about the pros we can say that:

• The mechanism of robot springs is powerful, because they can store so much energy.
• The number of shots is unlimited. It can be recharged and shoot for as many times as you need.
• The recharge time is so short. It does not take so much time for it to get armed again.
• It does not require so much energy; it gives you many shots by just using a simple battery.
• It is not that much heavy, at least compared to the pneumatic system.
• It is safe to work with.

Some disadvantages of this system are:

• You cannot adjust or change the shooting power while it is working.  
• The space you need for this system is a little bit high.

Pneumatic Systems

The second system used in a soccer robot kicking mechanism, is pneumatic system. In the pneumatic system, the air is compressed in order to produce energy. So this system requires a huge air tank. This air tank needs to be recharged before competitions so the robot kicker can shoot.

Like other systems there are some advantages and disadvantages to this system as well. Here are some of the advantages:

• The time between each shot is short and it gets armed quickly.
• It is safe compared to the solenoid system.
• It is not so expensive.

Some disadvantages of this system are:

• The shooting power decreases as the air tank gets empty. So the number of shoots is limited as well.
• If the gas tank gets empty, then you won’t have any more shoots.
• The gas tank takes up so much space in your robot and make it heavier.
• This pneumatic system is simpler than the solenoid model, but the spring mechanism is still the simplest mechanism.

Solenoids system

The third system which is used in kicking mechanism, is solenoid system. In this system, the Solenoids which are basically coils of wire, converts electricity to movement. The electricity must pass through them and create a magnetic field in order for a robot to kick. To have a stronger magnetic field you need to increase the number of cycles.

Advantages:

• By using this system, you can control the shooting power.
• The rearming time is short.
• The required space for this system is less than pneumatic system.

Disadvantages:

• The number of shoots depends on the power source you have.
• Since this system consumes a large amount of energy, a big power source is required (and also It makes your system heavier).
• In terms of security, this system is not really safe and it might harm the whole system output.
• The system is more complicated comparing to the two other systems.

In the following chart, all advantages and disadvantages of the above mentioned systems are summarized:

Characteristics/ Mechanism	Spring mechanism	Pneumatic mechanism	Solenoid mechanism
Shooting power	–	–	+
Weight	+	–	+
Space required	+	–	+
Time between shots	+	+	+
Safety	+	+	–
Simplicity	+	+	–
Number of shots	+	–	+
Cost	+	+	+

Conclusion

After reading this article, now you have a great understanding of how soccer robot kicking mechanism work and what are the different types of them.

Each system that are used in kicking mechanism has some advantages and disadvantages. When you’re trying to design and build a robot soccer player, you can consider these advantages and disadvantages and see which aspects can affect your whole system more.