CN110681133A - Bimodal control method for table tennis ball picking robot - Google Patents

Abstract

The invention relates to a dual-mode control method for picking up a table tennis robot. The working mode of the robot can be switched through the host computer App. In the automatic cruise mode, the robot obtains the position information of the table tennis ball in the field of view from the vision system, and adjusts the posture according to the coordinates of the ball to find the best collection angle; in the manual remote control mode The upper computer App sends motion commands to the robot through Bluetooth to control the robot's work; the robot also has an obstacle avoidance function, which can automatically avoid obstacles in two working modes. The advantages of the invention are as follows: the two working modes of automatic cruise and manual remote control can be switched at will, and with the function of obstacle avoidance, the application scene is widely used; when collecting table tennis balls in the automatic cruise mode, the robot can fine-tune its own posture according to the coordinates of the table tennis ball, and eliminate the The influence on the coordinates due to the field of view and distance is eliminated; the structure of the entire algorithm is clear and rigorous, and different functions correspond to different threads, which is easy for daily maintenance and secondary development.

Description

A dual-mode control method for a ping-pong robot

technical field

The invention relates to the technical field of robots, in particular to a dual-mode control method for picking up a table tennis robot.

Background technique

With the deepening of people's understanding of the intelligent nature of robotics, robotics has begun to penetrate into all fields of human activities. Among them, service robots, as an important branch, have received widespread attention in the field of research at home and abroad. Service robots have a wide range of applications, mainly engaged in maintenance, repair, transportation, cleaning, security, rescue, monitoring and other work. The ball picking robot involved in the present invention is an autonomous mobile service robot applied to table tennis sports.

The table tennis training field is relatively open, and athletes need to use a lot of table tennis balls in the training process, resulting in table tennis balls scattered around the field, and manual picking up of table tennis balls will waste a lot of time and energy.

At present, there are many auxiliary tools on the market that can help people to collect table tennis balls, but these tools still need to rely on manpower to collect the balls, and do not free people from this boring work.

The invention patent with the application number of 201810308608.9 discloses a ball picking machine, which can shovel the table tennis balls into the collection bucket and finally send it into the collection basket through the overturning and reset of the collection bucket, but because it cannot automatically find and collect table tennis balls The ball is still completely dependent on human remote control.

The invention patent with the application number of 201910121639.8 discloses a robot that can automatically cruise and collect table tennis balls, but it is not equipped with a ranging sensor and cannot avoid obstacles during the cruise. The collection of table tennis balls is very difficult, and generally cannot meet all the needs of daily use.

In view of the above situation, the present invention designs a dual-mode control method for picking up a table tennis robot, which adopts the dual-mode working mode of automatic cruise and manual remote control. ; When the ball is in a special position or you want to recycle the robot, you can switch to the manual remote control mode, and send motion commands through the host computer App to control the work of the robot, which greatly improves the work efficiency of the robot.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a dual-mode control method for picking up a table tennis robot, and the specific technical scheme adopted is as follows:

A working schematic diagram of a dual-mode control method for a table tennis robot is shown in Figure 2. The robot has two working modes: automatic cruise and manual remote control, which can be switched through the host computer App. The host computer App is developed based on the Android platform. Communication with the robot through Bluetooth can realize four functions of mode switching, obstacle avoidance function switch, wireless remote control and operation data monitoring of the robot.

Further, in the automatic cruise mode: the robot cruises in the entire field, and recognizes and locates the table tennis balls in the field of vision through the vision system. When the table tennis balls are recognized, the robot fine-tunes its posture and performs collection operations;

Further, in the manual remote control mode: the host computer App is connected to the robot through Bluetooth, and sends motion commands. After the robot receives the commands, it translates them into serial port commands, which are processed by the coprocessor and drive the car body to complete the specified motion.

Further, when the obstacle avoidance function is turned on: the program receives the distance information returned from the ultrasonic distance sensor in real time, and executes the obstacle avoidance operation if the distance from the obstacle is less than 15cm.

The present invention has the following advantages:

1) Two working modes of automatic cruise and manual remote control are adopted and can be switched at will. With the function of obstacle avoidance, the use scenarios are very wide;

2) When collecting table tennis balls in automatic cruise mode, its algorithm is optimized so that the robot can fine-tune its own posture according to the coordinates of the table tennis balls, and eliminates the influence of the field of view and distance on the coordinates;

3) The structure of the entire algorithm is clear and rigorous, and different functions correspond to different threads, which is easy for daily maintenance and secondary development.

Description of drawings

Fig. 1 is the structural representation of picking up table tennis robot in the embodiment;

Fig. 2 is the working schematic diagram of picking up table tennis robot;

Fig. 3 is the flow chart of the host computer App in the present invention;

Fig. 4 is the host computer App interface in the present invention;

Fig. 5 is the flow chart of manual remote control in the present invention;

Fig. 6 is the flow chart of automatic cruise mode in the present invention;

Fig. 7 is the flow chart of obstacle avoidance function in the present invention;

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

Detailed ways:

As shown in Figure 1, in the embodiment, the table tennis robot is composed of two parts: a ball picking device and a car body. The ball picking device is a ball bearing, long screw, hard plate, soft brush and other materials with fan blades The roller structure, through the combination of motor, belt and fixed pulley, drives the fan blade to rotate. When picking up the ball, the brush drives the table tennis ball to enter the ball storage device along the slope, so as to realize the collection of table tennis balls. Visual sensors and ultrasonic distance sensors are installed; the body part is a two-layer structure, and the upper layer is placed with a main and auxiliary two-level processor, lithium battery and a motor that drives the rotation of the fan blades of the ball picking device; the lower layer is placed with a ball storage device. It is in the shape of an open cuboid box, with the opening facing the front end of the car body, and stores the table tennis balls collected by the ball picking device. The lower chassis is equipped with four Mecanum wheels and their control motors, which can make the car body 360° arbitrary. direction move.

As shown in Figure 2, the working mode of the ping-pong ball picking robot can be switched by the host computer App. In the automatic cruise mode, the main control program of the robot can identify and locate the ping-pong ball in the field of vision according to the image information returned by the sensor, and drive the The robot adjusts its posture and collects table tennis balls; in the manual remote control mode, the App communicates with the robot through Bluetooth, sends motion commands, and drives the car body to complete the specified motion after the program is translated; the switch of the obstacle avoidance function is also controlled by the host computer App, when it is turned on When the robot is running, the program monitors the distance between the robot and the obstacle through the ultrasonic distance sensor, and executes the obstacle avoidance operation when it is less than the preset value; the important data generated when the robot is working will be sent to the App in real time through Bluetooth and displayed on its main page. interface, so that users can monitor the running status of the robot.

App Design:

As shown in Figure 3, the host computer App is developed based on Android. When it is working, it first obtains the BluetoothAdapter object to determine whether the device supports Bluetooth and whether Bluetooth is turned on. If it is not turned on, the openBlueSync method is called to prompt the user to turn on the bluetooth. After the bluetooth is turned on, call the The startLeScan and connectGatt methods scan and connect the Bluetooth serial port module, and the communication can start after the module is successfully paired and a stable connection is established. The entire communication read and write process is completed in the asynchronous callback function of BluetoothGattCallback. After all communication is completed, the software will call BluetoothGatt The disconnect and close methods in disconnect the connection with the robot's bluetooth module.

As shown in Figure 4, in the main interface of the host computer App, the connection status 1 between the App and the robot is displayed at the top, and the two buttons 2 and 3 below it correspond to the robot mode switching and obstacle avoidance functions respectively. You can change the working state of the robot by clicking the corresponding button; the remote control components 4 and 5 of the robot are located in the middle of the interface, drag the joystick 4 in the center to control the robot to move in eight directions, and the two arrow-shaped buttons below the joystick 5.1, 5.2 can make the robot rotate in the corresponding direction; the gray frame 6 at the bottom of the main interface is the data monitoring column, the current working data of the robot will be updated in real time in the column, including the information of on (off) the machine and table tennis in the field of vision , received motion commands, and distance to obstacles, etc.

Design of manual remote control mode:

As shown in Figure 5, in the manual remote control mode, the host computer App needs to establish a connection with the robot's Bluetooth module to transfer data to each other; in the main control program, each function runs on different threads without interfering with each other, and the mode sent by the App changes or The command of the switch function can be realized by blocking and activating the corresponding thread; if the App sends a remote control command, the two-level processor will translate the command into a serial port command and finally generate a PWM wave to control the encoder, driving the car body to complete the specified movement.

The serial port command format of the robot is shown in Table 1:

Table 1

A complete serial port command contains ten bytes, of which the first three bytes are the fixed command header, the fourth byte is the high 8 bits of the X-axis speed, and the fifth byte is the low 8 bits of the X-axis speed. , and the following four bytes correspond to the Y-axis and Z-axis speed respectively. The last byte is used to specify the positive direction of each axis, and the final motion of the robot is the vector sum of the three-axis motion. During the process, the information of the user's remote control will be transmitted to the host computer App in real time for display.

Design of automatic cruise mode:

As shown in Figure 6, there are two states in automatic cruise mode: cruise state and ball picking state;

When there is no ping-pong ball in the field of vision, the robot is in a cruise state. During the cruise, the robot moves forward in the current direction. When encountering an obstacle, it retreats a short distance and turns 75 degrees in the direction without obstacles. If there are obstacles on both sides object, then repeat the above operation, when the vision system recognizes the ball, the robot switches to the state of picking up the ball;

The state of picking up the ball is divided into an adjustment stage and a collection stage:

Adjustment stage: Since the field of view of the robot is a sector, coupled with the principle of perspective and the vibration of the image sensor, the coordinates that are identified for the first time are directly used for processing, which will reduce the success rate of collection. Therefore, after recognizing the ball, it is necessary to enter the adjustment stage to calibrate the position of the ball and the orientation of the robot. The principle is as follows. In the embodiment, the resolution of the camera used by the robot is 640*480, and the field of view is about 60 degrees. After repeated theoretical analysis And the experimental demonstration proves that when the distance between the robot and the table tennis ball is 20 to 40 cm, the collection effect of the ball's x coordinate is between 180 and 370. When the distance between the robot and the ball is 40 to 60 cm, the best collection interval is 200 to 340. During work, when the robot recognizes the ping pong ball, it will pause the movement, accurately identify the coordinates of the ball again, and then estimate the distance from the robot according to its radius, and select the appropriate optimal collection area. The difference between the interval coordinates is continuously adjusted until the table tennis ball is in the best collection interval and enters the collection stage;

Collection stage: According to the estimated distance, the approximate moving time is obtained and the vehicle body is driven to move. If a table tennis ball can still be recognized in the field of vision after performing a collection operation, the robot returns to the adjustment stage of the ball picking state and continues to pick up the ball. If there is no ping pong ball in the field of vision, it will change to the cruise state.

In the automatic cruise mode, the working data of the robot will be uploaded to the host computer App in real time, which is convenient for users to monitor and maintain the robot.

Design of obstacle avoidance function:

As shown in Figure 7, the obstacle avoidance function can be turned on or off on the host computer App; when the function is turned on, the program receives the distance information from the ultrasonic distance sensor in real time, and if the distance from the obstacle is less than the preset value of 15cm, execute Obstacle avoidance operation: The robot turns left and right on the spot to confirm whether there are obstacles on the left and right. After the confirmation, the robot turns 75 degrees in the direction where there are no obstacles. If there are obstacles on both sides, the robot backs up and performs the above confirmation operation again until There is no obstacle next to it, the robot turns to this direction and continues to work; the data in the obstacle avoidance state will be uploaded to the host computer App in real time.

Communication protocols involved in the method:

The main control program of the robot runs on the development board, and the visual sensor, Bluetooth module, ultrasonic ranging sensor communicate with the main control program through the serial port; the Bluetooth module adopts the HC-08 Bluetooth serial port communication module, and its wireless working frequency band is 2.4 GHz ISM, the modulation method is GFSK. The maximum transmit power of the module is 4dBm, and the receiving sensitivity is -93dBm. It can realize long-distance communication of 40 meters in an open environment. It uses the BluetoothSpecification V4.0 BLE Bluetooth protocol when connecting and data transmission with the App, and supports Android 4.3 and above systems.

Claims (5)

1. a dual-modal control method for picking up the robot of table tennis, it is characterized in that: picking up table tennis robot is made up of two parts of picking up ball device and car body, and picking up ball device is to utilize ball bearing, long screw rod, hard plate The roller structure with fan blades is composed of materials such as soft brushes and other materials. The combination of motor, belt and fixed pulley drives the fan blades to rotate. When picking up the ball, the brush drives the table tennis ball to enter the ball storage device along the slope. For the collection of table tennis balls, in addition, a visual sensor and an ultrasonic distance sensor are also installed on the ball picking device; the body part is a two-layer structure, and the upper layer is placed with a main and two-level processor, a lithium battery and a fan that drives the ball picking device. The motor that rotates the leaves; the ball storage device is placed on the lower layer, which is in the shape of an open cuboid box with the opening facing the front end of the car body, and stores the table tennis balls collected by the ball picking device. The lower chassis is equipped with four Mecanum wheels And its control motor can make the car body move in any direction of 360°; the robot has two working modes: automatic cruise and manual remote control, which can be switched through the host computer App. The host computer App is developed based on the Android platform and communicates with the robot through Bluetooth. It can realize four functions of robot mode switching, obstacle avoidance function switch, wireless remote control and operation data monitoring. 2. a kind of dual-modal control method for picking up the robot of table tennis according to claim 1, is characterized in that: in described automatic cruise mode, the main control program of robot returns according to the image information of sensor, to visual field In the manual remote control mode, the host computer App communicates with the robot through Bluetooth, sends motion commands, and drives the car body to complete the specified motion after program translation; The switch of the obstacle avoidance function is controlled by the host computer App. When it is turned on, the program monitors the distance between the robot and the obstacle through the ultrasonic distance sensor, and executes the obstacle avoidance operation when it is less than the preset value; The data will be sent to the App in real time through Bluetooth and displayed on its main interface, so that the user can monitor the running status of the robot; when the host computer APP is working, it first obtains the BluetoothAdapter object to determine whether the device supports Bluetooth and whether Bluetooth is turned on. When enabled, call the openBlueSync method to prompt the user to turn on Bluetooth. After the Bluetooth is turned on, call the startLeScan and connectGatt methods to scan and connect the Bluetooth serial port module. After the module is successfully paired and a stable connection is established, the communication can start. The entire communication read and write process is asynchronous in the BluetoothGattCallback. Completed in the callback function. After all communication is completed, the software will call the disconnect and close methods in BluetoothGatt to disconnect the robot's Bluetooth module; in the main interface of the host computer App, the top display is the connection status between the App and the robot. 1. The two buttons 2 and 3 below it correspond to the switch of the robot mode and the switch of the obstacle avoidance function respectively. You can click the corresponding button to change the working state of the robot; the robot remote control components 4 and 5 are located in the middle of the interface, drag the The joystick 4 in the center can control the robot to move in eight directions, and the two arrow-shaped buttons 5.1 and 5.2 below the joystick can make the robot rotate in the corresponding direction; the gray frame 6 at the bottom of the main interface is the data monitoring bar, the robot The current work data is updated in real time in the column, including the machine on (off), the information of the table tennis ball in the field of vision, the movement command received, and the distance to the obstacle. 3. a kind of bimodal control method for picking up the robot of table tennis according to claim 1-2, is characterized in that: in described manual remote control mode, host computer App needs to establish connection with the bluetooth module of robot, Transfer data to each other; in the main control program, each function runs on different threads without interfering with each other. The command sent by the App to change the mode or switch function can be realized by blocking and activating the corresponding thread; if the App sends a remote control command, The two-level processor will translate the instructions into serial port instructions and finally generate a PWM wave to control the encoder to drive the car body to complete the specified motion; the serial port instruction format of the robot is shown in Table 1: Table 1

A complete serial port command contains ten bytes, of which the first three bytes are the fixed command header, the fourth byte is the high 8 bits of the X-axis speed, and the fifth byte is the low 8 bits of the X-axis speed. , and the following four bytes correspond to the Y-axis and Z-axis speed respectively. The last byte is used to specify the positive direction of each axis, and the final motion of the robot is the vector sum of the three-axis motion; during the process, the information of the user's remote control will be transmitted to the host computer App in real time for display. 4. a kind of bimodal control method for picking up the robot of table tennis according to claim 1-2, is characterized in that: there are two kinds of states under automatic cruise mode: cruise state and picking up ball state; When there is no ping pong ball, the robot is in a cruising state. During the cruising process, the robot moves forward in the current direction. When encountering an obstacle, it retreats a short distance and turns 75 degrees in the direction without obstacles. If there are obstacles on both sides, then Repeat the above operation, when the vision system recognizes the ball, the robot switches to the state of picking up the ball; The ball picking state is divided into an adjustment stage and a collection stage: Adjustment stage: After recognizing the ball, you need to enter the adjustment stage to calibrate the position of the ball and the orientation of the robot; during work, when the robot recognizes the table tennis ball, it will pause the movement, accurately identify the coordinates of the ball again, and then estimate according to its radius. For the distance from the robot, select the appropriate optimal collection area, and continuously adjust the attitude according to the difference between the position coordinates of the table tennis ball and the coordinates of the optimal collection area, until the table tennis ball is in the optimal collection area and enters the collection stage; Collection stage: According to the estimated distance, the approximate moving time is obtained and the vehicle body is driven to move. If a table tennis ball can still be recognized in the field of vision after performing a collection operation, the robot returns to the adjustment stage of the ball picking state and continues to pick up the ball. If there is no ping-pong ball in the field of vision, it will change to the cruise state; in the automatic cruise mode, the working data of the robot will be uploaded to the host computer App in real time, which is convenient for users to monitor and maintain the robot. 5. a kind of bimodal control method for picking up the robot of table tennis according to claim 1-2, it is characterized in that: described obstacle avoidance function can be opened or closed on the host computer App; , the program receives the distance information returned from the ultrasonic distance sensor in real time. If the distance from the obstacle is less than the preset value of 15cm, the obstacle avoidance operation will be performed; Turn 75 degrees in the direction without obstacles. If there are obstacles on both sides, the robot will back up and perform the above confirmation operation again until there are no obstacles nearby, the robot will turn to this direction and continue to work; the data in the obstacle avoidance state will be real-time. Upload to the host computer App.

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