Discussion on joint simulation technology of mechatronics system

Taking mechatronics system as the research object, this paper analyzes the development status of fault-tolerant and error-correcting design and simulation technology of electromechanical products, and puts forward its own views.

Keywords: mechatronics simulation fault tolerance and error correction

I. Introduction

Modern electromechanical products are developing towards integration, automation and intelligence. Some mechanical and electrical products are less and less dependent on people, and it is impossible for someone to repair them if they fail. Some mechanical and electrical products form a large system, and once it fails, it may lead to major accidents and huge economic losses. For example, the Mars probes "Courage" and "Opportunity" launched by the United States have been flying in space for half a year, and once they fail, they cannot be diagnosed and maintained by people; In August 2008, a VLS 3 satellite launch vehicle in Brazil suddenly exploded during the final inspection, resulting in the death of 2 1 person at the scene, and more than 20 people were seriously injured.

These integrated, automatic and intelligent electromechanical systems are highly random and often unpredictable, but engineering practice shows that most failures are a gradual process except a few sudden failures. If it is found early, it is completely preventable to take appropriate measures in time. The research on fault-tolerant and error-correcting design and simulation technology of electromechanical products and the application of fault-tolerant technology meet this demand.

Fault-tolerant technology opens up a new way to improve the reliability of the system. Although people can't guarantee the absolute reliability of the components of the designed system, if the concept of fault tolerance is introduced into mechanical and electrical products, the influence of various fault factors on product performance can be significantly weakened, that is, the reliability of products can be indirectly improved. The research and application of fault-tolerant technology is of great significance to ensure the continuity and safety of electromechanical system operation, reduce safety accidents and improve the economic and social benefits of modern electromechanical products.

Second, the research status of bionic hardware fault tolerance

With the complexity of circuit system functions, the traditional hardware fault-tolerant technology can no longer meet the requirements of the increasingly large circuit system. In order to improve the reliability of the system, people put forward the requirements of dynamic self-detection and self-repair of faults, and strive to find new fault-tolerant design methods. As early as the late 1950s, the father of computers, Feng? Neumann put forward the great idea of developing a universal machine with the ability of self-replication and self-repair.

Inspired by nature, researchers introduced natural computing (such as evolutionary computing and embryo theory) into hardware design to form biologically inspired hardware (BHW). The concept of bionic hardware was first put forward by Swiss Federal Institute of Technology in 1992. Although its history is not long, it has developed very rapidly and has become one of the hot spots in international research. Bionic hardware was also called evolutionary hardware, EHW in the early days. A.Thompson and others put forward the idea of EHW applied to fault tolerance earlier. Bionic hardware is a kind of hardware circuit that can change its structure and behavior autonomously and dynamically according to the change of external environment to adapt to its living environment. It can have the characteristics of hardware adaptation, self-organization and self-repair like a living body. Using bionic hardware to realize fault tolerance does not need explicit redundancy, but uses the inherent fault tolerance characteristics of evolution itself to bring incomparable advantages through static redundancy.

Thirdly, a new idea of bionic hardware fault-tolerant technology.

The research on fault tolerance based on bionic hardware is of great significance for establishing a new theory, model and method of hardware fault tolerance based on biological evolution mechanism and improving the reliability of hardware system.

(1) Fault-tolerant architecture and principle of embryonic bionic hardware.

Bionic hardware can be divided into evolutionary and embryonic types, among which embryonic bionic hardware, also known as embryonic electronic system, is the hardware that imitates the multi-cell fault-tolerant mechanism of organisms.

The fault-tolerant architecture of embryonic bionic hardware is mainly composed of embryonic cells, switch arrays and stitches. According to the control signal of programmable connection, the switch array completes the switch closing and controls the use of each line segment in the control track. Embryonic cells include memory, coordinate generator, I/O exchange block, functional unit, direct connection, programmable connection, control module and so on. The memory is used to store the configuration bit string, and extract the decoded segment from the configuration bit string according to the cell state and the calculation result of the coordinate generator, so as to configure the commutation block and functional unit of the embryonic electronic unit. The coordinate generator assigns coordinates to each cell according to the coordinates of adjacent cells on the nearest two sides (left and lower sides). I/O commutation block provides control signals for programmable connection between functional units. The functional unit is used to realize the N-input Boolean function, which is used to realize the required cell function. Direct connection is responsible for communication between functional units. Programmable wires transmit control signals to control the switch array. The control module completes the working state detection, fault diagnosis and redundant switching of the battery.

(2) The strategy to realize the fault tolerance of embryonic bionic hardware.

In order to realize fault tolerance of fault cells, there are two common fault tolerance strategies: row (column) cancellation and cell cancellation. By recording the location of faulty batteries, rewire them and replace them with other spare batteries.

However, these strategies do not give corresponding countermeasures for the failure of connection resources. Based on the in-depth study of the fault-tolerant architecture of embryonic bionic hardware, a fault-tolerant strategy for line-rail faults is proposed.

1. Line (column) cancels the policy. In row (column) cancellation, if a cell makes an error, all cells in its row (column) will be cancelled, and the function of the cell in this row (column) will be replaced by the cell in its previous row (right column), that is, when a cell makes an error, its row (column) will be moved up (right) to an alternate row (column) to replace its current work.

2. Cell elimination strategy. In the process of unit cancellation, there are two stages to replace the failed units with standby units. When the number of wrong cells in a row exceeds the number of spare cells, the whole row is cancelled, the cells in the row move up, and the spare row replaces the wrong row.

(3) The realization process of embryonic bionic hardware fault tolerance.

The fault-tolerant process of embryonic bionic hardware is as follows:

(1) Select devices according to the design requirements and determine the hardware design scheme;

(2) coding the circuit structure and related parameters into chromosomes, and performing evolutionary operation on the system according to the evolutionary mode of the evolutionary algorithm;

(3) Generally, the degree of conformity between the function of the circuit and the expected result is regarded as individual fitness. According to the given input conditions or test set, based on the circuit model, the fitness of each individual in the group is calculated through simulation test or actual measurement;

(d) The internal error detection mechanism of embryonic bionic hardware.

Error detection is the premise for embryonic bionic hardware to realize fault tolerance. This paper mainly studies the error detection mechanism of unit failure.

Modular redundancy and majority voting circuit implementation based on cellular functional units are commonly used redundancy fault-tolerant strategies for hardware fault tolerance.

Most voters judge and output the signals of most cell modules, but they can't judge which cell has a problem, so they can't start the restart or reconstruction of the wrong cell to repair it. In order to detect the specific location of the fault unit, repair the unit and further improve the reliability of the three-mode redundancy, it is necessary to design the corresponding error detector.

References:

[1] Gao Jinji, research on self-healing principle of equipment system. China Engineering Science, 2009(5).

Research on the structure of fault-tolerant parallel processing system. Computer Applications, 2008( 1).

Yao Rui, Yu Yu, Research on Embryonic Bionic Hardware and Its Key Technologies. Journal of Henan University of Science and Technology, 2009(3).