What is a robot control system?
Even with just senses and muscles, a person's limbs cannot move. This is because there are no organs to receive and process the signals from the senses, and also because there are no organs to send nerve signals to drive the muscles to contract or relax. Similarly, if a robot only has sensors and actuators, its robotic arm cannot function properly. This is because the signals output by the sensors are ineffective, and the drive motors do not receive the necessary voltage and current. Therefore, a robot needs a controller, a control system composed of hardware and software.
The function of a robot control system is to receive detection signals from sensors and drive the various motors in the robotic arm according to the requirements of the operational task. Just as human activity relies on our senses, robot motion control is inseparable from sensors. Robots need sensors to detect various states. Internal sensor signals are used to reflect the actual motion state of the robotic arm joints, while external sensor signals are used to detect changes in the working environment.
Therefore, a robot's neural network and brain must be combined to form a complete robot control system.
What aspects are included in the motion control system of a robot?
Actuator – servo motor or stepper motor;
Drive mechanism ---- servo or stepper driver;
Control mechanism – motion controller , which performs algorithmic calculations and controls the path and motor linkage;
Control method: If there is a fixed execution action method, then program the motion controller with fixed parameters.
If a vision system or other sensors are added, a program with variable parameters is written for the motion controller based on the sensor signals.
Basic functions of robot control system
1. Control the movement position of the robotic arm's end effector (i.e., control the points the end effector passes through and the path of movement).
2. Control the movement posture of the robotic arm (i.e., control the relative position of two adjacent moving parts);
3. Control the motion speed (i.e., control the change of the end effector's position over time);
4. Control the motion acceleration (i.e., control the speed change of the end effector during the motion process);
5. Control the output torque of each power joint in the robotic arm: (i.e., control the force applied to the manipulated object);
6. It has user-friendly human-computer interaction functions, and the robot completes the prescribed tasks by memorizing and reproducing information;
7. Enable robots to detect and sense their external environment. Industrial robots are equipped with vision, force, and tactile sensors to measure, identify, and judge changes in working conditions.
Industrial robot control system
1. Hardware Structure of Industrial Robot Control System
The controller is the core of a robot system, and foreign companies have imposed strict embargoes on it in my country. In recent years, with the development of microelectronics technology, microprocessors have become increasingly powerful and affordable, with 32-bit microprocessors now available for as low as $1-2. These cost-effective microprocessors have brought new development opportunities to robot controllers, making it possible to develop low-cost, high-performance controllers. To ensure sufficient computing and storage capabilities, current robot controllers mostly use high-performance chips such as ARM, DSP, POWERPC, and Intel chips.
Furthermore, since existing general-purpose chips cannot fully meet the requirements of certain robot systems in terms of price, performance, integration, and interfaces, there is a demand for System-on-Chip (SoC) technology in robot systems. Integrating a specific processor with the required interfaces can simplify the design of peripheral circuits, reduce system size, and lower costs.
For example, Actel integrates NEOS or ARM7 processor cores into its FPGA products, forming a complete SoC system. In the field of robot motion controllers , research is mainly concentrated in the United States and Japan, with mature products such as those from DELTATAU (USA) and PTZ (Japan). Their motion controllers are based on DSP technology and employ a PC-based open architecture.
2. Industrial Robot Control System Architecture
In terms of controller architecture, the research focus is on functional partitioning and the standardization of information exchange between functions. In the research of open controller architectures, there are two basic structures: one is a hardware-layer-based structure, which is relatively simple. In Japan, the architecture is partitioned based on hardware; for example, Mitsubishi Heavy Industries divides its PA210 portable general-purpose intelligent arm robot into a five-layer structure. The other is a function-based structure, which considers both hardware and software, and is the direction of research and development in robot controller architecture.
3. Control the software development environment
In terms of robot software development environments, most industrial robot companies have their own independent development environments and independent robot programming languages, such as Japan's Motoman, Germany's KUKA, the United States' Adept, and Sweden's ABB.
Many universities have conducted extensive research on robot development environments, providing a wealth of open-source code that can be integrated and controlled under certain robot hardware architectures. Numerous related experiments have already been conducted in laboratory environments. Existing robot system development environments both domestically and internationally include TeamBots v.2.0e, ARIA v.2.4.1, Player/Stage v.1.6.5.1.6.2, Pyro v.4.6.0, CARMEN v.1.1.1, MissionLab v.6.0, ADE v.1.0beta, Miro v.CVS-March17.2006, MARIE v.0.4.0, FlowDesigner v.0.9.0, RobotFlow v.0.2.6, and many more.
From the perspective of the development of the robotics industry, there are two demands for robot software development environments. One demand comes from end-users of robots, who not only use robots but also want to give them more functions through programming. This programming is often implemented using visual programming languages, such as the graphical programming environment of LEGO MindStormsNXT and the visual programming environment provided by Microsoft Robotics Studio.
4. Robot-specific operating system
(1) VxWorks. VxWorks is an embedded real-time operating system (RTOS) designed and developed by Wind River Systems in 1983. It is a key component of the Tornado embedded development environment. VxWorks features a customizable microkernel architecture; efficient task management; flexible inter-task communication; microsecond-level interrupt handling; support for the POSIX 1003.1b real-time extension standard; and support for various physical media and standard, complete TCP/IP network protocols.
(2) Windows CE. Windows CE has good compatibility with the Windows series, which is undoubtedly a major advantage for the promotion of Windows CE. Windows CE provides a feature-rich operating system platform for building dynamic applications and services for handheld devices and wireless devices. It can run on a variety of processor architectures and is generally suitable for devices with certain limitations on memory footprint.
(3) Embedded Linux, due to its open source code, can be freely modified to meet individual application needs. Most of it complies with the GPL, meaning it is open source and free. It can be applied to users' own systems with slight modifications. There is a large developer community, requiring no specialized talent, only knowledge of Unix/Linux and C language. It supports a vast number of hardware. Embedded Linux is not fundamentally different from ordinary Linux; it supports almost all hardware used on PCs. Moreover, the source code for drivers of various hardware is readily available, greatly facilitating users in writing drivers for their own proprietary hardware.
(4) μC/OS-II. μC/OS-II is a well-known open-source real-time kernel designed for embedded applications and can be used with 8-bit, 16-bit and 32-bit microcontrollers or digital signal processors (DSPs). Its main features are open source code, good portability, firmware compatibility, customizability, preemptive kernel, determinism, etc.
(5) DSP/BIOS. DSP/BIOS is a customizable real-time multitasking operating system kernel designed and developed by TI specifically for its TMS320C6000TM, TMS320C5000TM, and TMS320C28xTM series DSP platforms. It is a component of TI's CodeComposerStudio™ development tool. DSP/BIOS mainly consists of three parts: a multi-threaded real-time kernel; real-time analysis tools; and chip support libraries. Using a real-time operating system to develop programs allows for convenient and rapid development of complex DSP programs.
5. Robot servo communication bus technology
Currently, there is no dedicated servo communication bus for robot systems internationally. In practical applications, commonly used buses such as Ethernet, CAN, 1394, SERCOS, USB, and RS-485 are typically used in robot systems according to system requirements. Most current communication control buses can be categorized into two types: serial bus technology based on RS-485 and wire-driven technology, and high-speed serial bus technology based on real-time industrial Ethernet.
Intelligent robot control system
1. Open and modular control system architecture: Utilizing a distributed CPU computer architecture, it consists of a robot controller (RC), a motion controller (MC), an opto-isolated I/O control board, a sensor processing board, and a programming teach pendant. The robot controller (RC) and the programming teach pendant communicate via a serial port/CAN bus. The main computer of the robot controller (RC) handles the robot's motion planning, interpolation, position servoing, main control logic, digital I/O, and sensor processing, while the programming teach pendant displays information and provides key input.
2. Modular and Hierarchical Controller Software System: The software system is built on the open-source real-time multitasking operating system Linux, employing a layered and modular structure to achieve openness. The entire controller software system is divided into three layers: the hardware driver layer, the core layer, and the application layer. Each layer addresses different functional requirements and corresponds to different levels of development. Each layer consists of several functionally independent modules that collaborate to achieve the functions provided by that layer.
3. Robot fault diagnosis and safety maintenance technology: Diagnosing robot faults and performing corresponding maintenance through various information is a key technology to ensure robot safety.
4. Networked Robot Controller Technology: As robot applications evolve from single robot workstations to robot production lines, networking technology for robot controllers is becoming increasingly important. Controllers feature serial ports, fieldbus, and Ethernet networking capabilities. This allows for communication between robot controllers and between robot controllers and host computers, facilitating the monitoring, diagnosis, and management of robot production lines.
