How did I make a table tennis  Robot?

IDEA

the Idea of this project is to make a robot that trains people to play tennis table by shooting the ball atomically based on the configuration you can control.

Design

The design consists of 3 main parts

• The mechanism which loads the balls and controls the ball rate is "the time between two consecutive balls".
• The shooting mechanism directs the ball all over the table and controls its speed and spin.
• The box includes all the needed electronics. so let us starts with the first part.

The loading mechanism

Consists of 3 main parts

The pipe 

I used a 2-inch PVC pipe and simply modify it to be like the image below.

The container 

I reused an old box to mad it and made a hole in its base and attach it with the pipe and now the static part is ready.

The moving part

For this part, I used a NEMA17 stepper motor to move 3 PVC half-rings glued to its shaft, but at the end of the project, I replaced them with a piece of 12mm plywood laser cut. And the motor pushes the balls to a 90-degree pipe angle. I attach the motor and the 90-degree pipe angle to a piece of plywood.

This 90-degree pipe angle is connected to a 2-inch pipe which is also connected to another 90-degree pipe angle on the other side.

The shooting mechanism

The mechanism through the balls simply consists of 2 pulleys attached to 2 motors when the ball move inside them they will push it forward and based on the speed of both of them we can control the speed and spin of the ball.

I used 2 brushless motors 1000kv (XXD A2212) and 2 30A ESCs to control all wiring details and codes in the sections below.

I used a 1.5-inch PVC pipe and I made 2 holes in the upper and lower half of it to fit the 2 pulleys.

and for the motor fixation, I 3d printed it and you can find the STL part in here. 

and to move this part to hit different sides of the table I attached a servo motor to the upper PVC 90-degree pipe angle and its shaft to the shooting part

The electronics 

I reused another old box to be the container for the electronics which are :

• power supply 12v 10A to supply the whole system.

• Arduino Uno, to control all the motors.

• Bluetooth module HC-05 to communicate with the robot and adjust its configuration.

• 2 ESCs to control the brushless motor as I mentioned above

• TMC2208 motor driver for the steeper motor

• 5v power supply to supply the servo.

The wiring

system wiring as below

Arduino code

you can download the Arduino code Here

it simply read the data from the mobile application and then updates the robot configuration based on it.

mobile application

Unfortunately, the mobile application is only for android now and you can download it from here.

you can see a full video here