RU2715370C1 - Architecture of mobile robot control system - Google Patents

Abstract

FIELD: robotics.

SUBSTANCE: invention relates to control of mobile robotic systems, in particular mobile robots. Essence of the invention consists in the fact that the mobile robot control system has a hierarchical architecture, besides, each device included into the system, has communication with other devices by means of two lines: command bus and data bus. Each system device has a processor or microcontroller. Location of all data in random access memory connected to processor or microcontroller of control system device has the form of registers of commands and data registers. Command registers data transmission is performed in the form of sending and receiving messages via command bus, data registers data transmission is performed in the form of sending and receiving messages via data bus. Device which generates commands and the device which generates data initiate transmission of commands and data accordingly and determine frequency of updating values of registers of recipient devices. Given architecture of the mobile robot control system enables the devices included in the control system to send and receive control commands and data asynchronously and independently from each other.

EFFECT: when using separate command and data buses, collisions are eliminated when transmitting commands and data over a single line, and possibility of increasing command and data transmission speed is also possible.

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Description

The invention relates to the field of control of mobile robotic complexes, in particular mobile robots.

A software control device is known (application for invention 94025187/09, 07/04/1994, publication date 05/27/1996), in which the following are connected to a single information line: program input device, interrupt controller, calculator, reprogrammable memory device, remote controller operator, digital pulse-phase control system. The device also includes a thyristor converter, conductivity and current sensors, an electric motor, speed and position sensors, an electric automation unit.

The disadvantage of this program control device is the presence of a single information line for transmitting and receiving control commands and data by devices included in the system of the program control device.

The objective of the invention: improving the architecture of the control system in order to eliminate collisions in the transfer of commands and data on a single highway, as well as gaining the ability to increase the transmission speed of commands and data.

The problem is solved in that the control system of the mobile robot has a hierarchical architecture, moreover, each device included in the system has communication with other devices via two lines: command buses and data buses (Fig. 1). The exchange of information between all devices connected to the command bus and the data bus is performed by sending and receiving messages, and each message frame has a byte sequence format (Fig. 2).

In the control system of a mobile robot, each subordinate device of the system is subordinate to the superior through control commands. The transmission of control commands in the system is carried out from the superior device to the lower device (several lower devices) via the command bus, and data is transferred from the data shaper device to the destination devices (higher devices, lower devices and devices of a similar hierarchy level with the data shaper device ) through the data bus, moreover, the transfer of commands and data is possible directly to the recipient device bypassing the intermediate devices due to in that commands and data are transmitted via the bus commands and data bus, respectively, with such an arrangement the tire to broadcast commands and data from one source device to multiple receiving devices (Fig. 1).

The highest level of the device hierarchy is the first level (Fig. 1). The device of the first hierarchy level is the parent for all other devices of the control system. The minimum number of devices in the mobile robot control system is two, and only one of the devices can have the first level in the device hierarchy of the control system. The device hierarchy level decreases as the device level number increases.

 The physical level of the bus interfaces of the control system is a differential pair (serial interface), which ensures high stability of the transmitted signal to common mode interference.

 Each device of the control system has a processor or microcontroller that transmits / receives commands and data, collects, processes and stores data of sensors of physical quantities, controls the actuators or actuators of the robot, and transmits / receives information via radio. The location of all data in the RAM connected to the processor / microcontroller of the control system device has the form of one-dimensional arrays of constant length. Each element of such an array is a place to store the current value of a certain value in digital form, reflecting information:

 - about control commands transferred to subordinate elements of the control system,

 - on the state of the mobile robot and its environment (data received from sensors, processors / microcontrollers).

 Each value in a static one-dimensional array occupies a fixed and non-moving region of memory - a register, the transition to which is carried out by indicating the constant index (number) of the desired array element.

 All registers are divided into two groups:

 - registers of commands,

 - data registers.

 Registers of the sent commands are located in the RAM of the device forming the command (superior device) and are accessible only to him for reading and writing. The RAM of the downstream devices contains the registers of the received commands of the parent device - the parent device has the ability to write commands to the registers of the slave device, while the downstream device can only read its registers of received commands.

 Registers of sent data are located in the RAM of the devices that form this data and are accessible only to them for reading and writing. The registers of received data are located in the RAM of the recipient devices, and are read-only for them - the data shaper has the ability to write data to the received data registers of these devices.

 Command registers and data registers are placed in arrays of command registers and arrays of data registers, respectively. The information transfer of the command registers is performed in the form of sending and receiving messages on the command bus, the information transfer of the data registers is performed in the form of sending and receiving messages on the data bus.

 The frame of each command / data message has a byte sequence format (FIG. 2), including:

 - beginning of the message (preamble) - is the identifier (marker) of the beginning of the message; the preamble may also include information that the message data must be recorded in certain types (modules) of memory, or that the current message is a request / permission to transmit data;

 - originality identifier of the message - the message can be either original (from the sending device to the receiving device) or an echo message (from the receiving device to the sending device);

 - identifier of the recipient device to whom the command or data is addressed;

 - identifier of the sending device;

 - the value of the length of the data fragments of the message frame in the number of bytes (indicates the total length of the fragments of the frame, which are the numbers of the command registers and their values or the numbers of the data registers and their values);

 - one or more consecutive pieces of data of the message frame;

 - checksum of the entire message frame.

The architecture of the mobile robot control system works as follows.

 The device forming the command, and the device forming the data initiate the transfer of commands and data, respectively. Thus, these devices determine the refresh rate of the register values of the received data of the recipient devices.

 In order to ensure detection and elimination of collisions during the transmission of data / commands between devices, the transmitting device must determine the presence of a signal (interference) of another device in the transmission medium (bus) before transmitting commands / data. If interference from another device is present in the transmission medium, the transmitting device delays the transmission, transmits through the command / data bus a special interference message informing all devices connected to the bus about the need for them to complete the transmissions and waits for a certain period of time before resuming transmission .

 Error control of command / data transmission is performed in two ways:

 - the receiving device transmits a response echo message to the sending device - the sending device compares the data (values of registers and data / commands) in the response message with the data in the sent message and, if the data does not match, the sending device repeats the broadcast;

 - at the end of each message frame there is a checksum designed to check the integrity of the message frame, two or more bytes long - when receiving the message, the recipient device calculates the message checksum without taking into account the sent checksum and compares the result of its calculations with it: if their values are not match, the message is ignored.

 All registers have the same length. For many robotics tasks, the length of one register of 2 and 4 bytes is sufficient - to store 16- and 32-bit numbers, respectively. Stored numbers can be signed or unsigned. With a register length of 4 bytes, a single precision floating-point number can be stored. Possible register length of 8 bytes or more.

 If you need to work with data arrays of dimension greater than one (two-dimensional array, three-dimensional array, etc.), the elements of these arrays are placed in the registers, while multidimensional arrays have a fixed length and are represented as a one-dimensional array of arrays. In this case, the data shaper transmits multidimensional data arrays to the recipient devices in parts.

 The operation of a mobile robot control system using this architecture and consisting of three devices (Fig. 1) can be performed as follows.

 Level 1 device 1 generates and sends commands via the command bus to device 2 and device 3 of level 2: for device 2 - a command to start a radio transceiver connected to device 2 to transmit data on the status of a mobile robot to a remote control via a radio channel a robot; for device 3, a command about collecting data from physical quantity sensors connected to device 3. Level 1 device 1 generates and sends commands on the command bus to level N device N: a command about collecting data from physical quantity sensors connected to device N and a command about generating device N control pulses for driver drive control circuits or actuator control circuits that are connected to device N. Level 1 device 1 is superior to device 2 and level 3 device 3, set N level N.

 The device 3 level 2 and the device N level N form and send alternately the data on the data bus device 1 level 1 and device 2 level 2. The data bus performs the function of feedback in the control system of the mobile robot.

This architecture of the mobile robot control system allows devices included in the control system to asynchronously and independently send and receive control commands and data. When using separate command and data buses, collisions are eliminated when transmitting commands and data on a single highway, and it is also possible to increase the transmission speed of commands and data.

Claims (1)

The architecture of the mobile robot control system, consisting of devices connected to a single information highway, characterized in that the mobile robot control system has a hierarchical architecture, with each subordinate device of the system being subordinate to the parent by executing commands transmitted from the parent device to a lower device or several lower ones devices via the command bus, and data transmission is performed via the data bus from the driver; yes recipient devices, which can be superior devices, downstream devices, and devices of a similar hierarchy level with a data shaper device, while the top level of the device hierarchy is the first level, and the device of the first hierarchy level is superior to all other devices of the control system, moreover, the minimum number of devices in the mobile robot control system is equal to two, and only one of the devices can have the first level in the system hierarchy of devices we control, while the hierarchy level of the device decreases with increasing device level number, while the transfer of commands and data is possible directly to the recipient device, bypassing intermediate devices due to the fact that commands and data are transmitted via the command bus and data bus, respectively, and with such a bus organization broadcasting of commands and data from one source device to several recipient devices is possible, while the physical level of the bus interfaces of the control system is I am a differential pair, which ensures high stability of the transmitted signal to common mode interference, moreover, each device in the system has a processor or microcontroller that transmits and receives commands and data, collects, processes and stores data of sensors of physical quantities, controls drives or actuators of the robot, transfers and receiving information by radio, while the RAM or memory is connected to the processor or microcontroller, the location of all the data in which has the form of command registers and p data histories, and the transfer of information of the command registers is performed by sending and receiving messages on the command bus, the transmission of information of the data registers is performed by sending and receiving messages on the data bus, while the device forming the commands and the device forming the data initiate the transfer of commands and data, respectively, that these devices determine the refresh rate of the register values of the recipient devices, and each frame of command and data messages has the format of a byte sequence including : Beginning of the message, which is the beginning of the message identifier and may include information that these messages must be stored in certain types of memory, and that the current message is a request or permission to transmit data; the originality identifier of the message, which indicates that the message is original and sent from the sending device to the receiving device or is an echo message and sent from the receiving device to the sending device; the identifier of the recipient device to whom the command or data is addressed; Sender ID the value of the length of the data fragments of the message frame in the number of bytes, which indicates the total length of the data fragments of the message frame, which are the numbers of the command registers and their values or the numbers of the data registers and their values; data fragments of the message frame, which are one or more consecutive data fragments of the message frame; checksum of the entire message frame, designed to verify the integrity of the message frame.

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