In this paper, there is proper designing of the ping pong ball server. For that game, there is a need to design a linkage mechanism that can easily operate through the help of a motor at a constant speed. Moreover, it will also transform the rotary motion of the input in the form of translational motion and oscillatory motion. The main aim of this server is that it is able to hit the ping-pong ball with efficient power. For that case, there is a need for a linkage mechanism that will hit the ball towards the person that is standing at the other end.

In this report, there is a need to design a robot arm that will act as a server. For that case, there is complete information about the linkage design of the server. Then after this, there is a complete demonstration of the drive mechanism design of the server in a proper way. Moreover, in the last, there is a complete proposed design for the customer. It can be noted that robots are helping us to understand the human adaptive behavior in an efficient way. Furthermore, such behavior includes different kind of movements like manipulation of objects, locomotion and other activities. This can be in the form of ping pong server. It is also considered as a valuable tool for the high speed human interaction like making moment and prediction. Due to this fact, it will become extremely simple to serve the ping pong ball in a proper way.

There are many researchers that are working on such robots that will serve ping pong ball easily without any difficult. Such robot servers have the ability to hit the ball anywhere they wanted in the court. Moreover, it also contain only one arm and due to this it will become extremely difficult for the human to predict.

In this section, there is complete information about the design specification for building a ping pong server. The whole server will be designed according to these design specification. Ping pong server design specification are given in the table below

Required items	Complete specifications
Mass of the total server	5 kg with complete mechanism of the motor and harmonic gears
Required degree of freedom	6 DOFs
Upper arm length	0.30 m
Forearm length	0.22
Racket length for server	0.15
Range constraints of all joints	Shoulder · Pitch -60 · Roll -90 · Yaw -90 Elbow · Pitch 0 · Yaw -90 Wrist · Pitch -60 · Roll -60
End velocity of the system	Greater than 3 m/s

Design of the ping pong server

In this section there is complete information about the design. It will also discuss its linkage mechanism with complete details. It can be noted that the ping pong server appearance is completely different and contains anthropomorphic shape. Due to this fact it motion can be detected easily by the human player. Moreover, this sever contains several joints and actuators for making different kind of actions. Its striking motion can hit the ball anywhere in the court. The next thing is that there is need to maintain the weight of the robot properly. This is because as the weight of the robot is increased its speed will be decreased effectively. Due to this case, in this server one actuator is used to move three joints. Due to this, there will be less number of actuators and sever weight will be lowered. Now the ping pong server can only contain two kind of motions. It will move from side to side and lean forward to hit the ball. This design approach can be used for other servers that will move in a fast way. Moreover, it will also easy for this server to interact with the human player.

Figure 1: Ping pong number of joints

In this server, there are about six joints. The six joint are given in the figure above. The name of this joints are base, hip, racket hand, forearm, upper-arm and chest.

Linkage mechanism

Figure 2: linkage mechanism

The linkage mechanism of the ping pong server is given in the above figure. It is showing that there are about eight main joints that are named as X and Y joint of the slider. The next thing is that Z is joining the base, chest, forearm and upper-arm. This linkage mechanism coordinates the wrist, shoulder and elbow. Furthermore, electric motors are involved in actuating the X and Y joints.

Drive mechanism of Machine design for the ping pong ball server

This section will give information about how different drives used for making a ping pong server. This part will discuss complete drive mechanism. For drive, there are two DC wiper motors are used. These motor will be operated on 12 volts. The main purpose of these motors are to drive the joints at smooth and fast speed. Moreover, the weight of such motors is low will provide more flexibility to the server. Furthermore, its torque is also high. This table will help select the perfect motor for making the server.

The maximum torque is required is more than 400, this means that the motor with 1500 torques is suitable for the ping pong server. This is the reason why DC wiper motor is used in this case.

Initial tensors given by

Information about the ping pong ball server dimension requirement

This section will discuss important parameters of the robot in a proper way. For this purpose, the first parameter is related to the ball locus and measurement and its forecast. This is done by the binocular camera and measuring plane. It is showing that when the ball is crossing the measuring plane. Such ball crossing can be measured through the triangulation principle. These equations are given below

Now the velocity of the ping pong ball will be calculated when it will cross the lower measuring planes. This shows that its velocity at three axis will be given by

The next parameter is related to the reference paddle locus, and it is calculated in four main conditions and it will allow the server to hit the ball several times. In the start, the speed of the ball will be increased after hitting. In the last this reference paddle locus is calculated under these conditions

Figure 3: paddle locus of the ser

Moreover, other parameters are related to the inverse kinematics will be given below

Position vector

Angular velocity

Angular acceleration

Torque is given by

Force can be calculated

Designing of gear train and motor system

The design of gear train is extremely important for the server. This is because due to gear train system it can easily move it arm and hit the ball in the table tennis court. In this section there is complete information about the designing of gear train of the server. According to the given problem the arm of the server will move with the velocity of 10 m/s. this is because it has to hit the ball with more power. The diameter of the drum will be considered as 15 cm.

Power can be calculated easily

In this equation, N is the angular velocity and T is the torque of the motor.

Now the maximum bending moment can be calculated easily

Stress due to bending

Stress formed due torque will be

The design equation will become

Motor system of Machine design for the ping pong ball server

These motor will be operated on 12 volts. The main purpose of these motors are to drive the joints at smooth and fast speed. Moreover, the weight of such motors is low will provide more flexibility to the server. Furthermore, its torque is also high. This table will help select the perfect motor for making the server.

Sr. number	Motor torque	Speed of motor	Power input to motor	Mass of motor
1	1660 kg	7.55 rpm	1230 watts	25 kg
2	1500	6.44	1150 watts	20 kg
3	302	22.2	660 watts	4 kg
4	68	45	333 watts	1.3kg

Swing experiment of Machine design for the ping pong ball server

This section will discuss some motion details of the system. This shows that the motion of the server will be measured in this section in a proper way. The swing of the server will make to different pattern. These patterns are called as driving and pushing from the given experiment. The next fact is that the main commands of the swings are determined through the help of error and trial. For that case, there is need to set the pressure of supplied air is about 0.7 MPa. According to this case, the motion of the server is measure by means of motion capturing cameras. For that case, a proper marker was attached on the racket that will measure its position. It can be noted that this motion capturing system is measuring its position at 120 frames per second of the camera. According to this experiment the velocity and acceleration of the server’s racket is determined.

Loading and timing mechanism through cam Simulation results

Figure 4: linkage diagram on simulator

Figure 5: Axis plotting

Figure 6: Linkage velocity graph

Figure 7: Linkage acceleration graph

Conclusion of Machine design for the ping pong ball server

Summing up all the discussion from above, it is concluded that the ping pong ball server is quite easy to design through the help of these design calculations. . For that game, there is a need to design a linkage mechanism that can easily operate through the help of a motor at a constant speed. For that case, there is complete information about the linkage design of the server. Then after this, there is a complete demonstration of the drive mechanism design of the server in a proper way

Furthermore, such behavior includes different kind of movements like manipulation of objects, locomotion and other activities. This can be in the form of ping pong server. It can be noted that the ping pong server appearance is completely different and contains anthropomorphic shape. Due to this fact it motion can be detected easily by the human player. For drive, there are two DC wiper motors are used. These motor will be operated on 12 volts. The main purpose of these motors are to drive the joints at smooth and fast speed.

References of Machine design for the ping pong ball server

Chen, X., Tian, Y., Huang, Q., & Weimin Zhang, a. Z. (2010). Dynamic model based ball trajectory prediction for a robot ping-pong player. In 2010 IEEE International Conference on Robotics and Biomimetics, .

Tian, J.-D., & Jing Sun, Y.-D. T. (2011). Short-baseline binocular vision system for a humanoid ping-pong robot. Journal of Intelligent & Robotic Systems.

Yang, P., Zhang, Z., Wang, H., & Xu, D. (2010). Design and motion control of a ping pong robot. In 2010 8th World Congress on Intelligent Control and Automation.

Yu, Z., Liu, Y., Huang, Q., & Xuechao Chen, W. Z. (2013). Design of a humanoid ping-pong player robot with redundant joints. In 2013 IEEE International Conference on Robotics and Biomimetics.

ZHANG, Y., & XIONG, R. (2012). Real-time vision system for a ping-pong robot. Scientia Sinica Informationis.

Zhang, Y.-h., Wei, W., & Dan Yu, a. C.-w. (2011). A tracking and predicting scheme for ping pong robot. Journal of Zhejiang University SCIENCE C 1.