GB2400692A

GB2400692A - A development and test methodology using synthetic environments

Info

Publication number: GB2400692A
Application number: GB0300720A
Authority: GB
Inventors: Alan James Veitch; Roger Travers Harriss; Bernard Fowler
Original assignee: MBDA UK Ltd
Current assignee: MBDA UK Ltd
Priority date: 2002-01-14
Filing date: 2003-01-13
Publication date: 2004-10-20
Also published as: FR2859803A1; GB0300720D0; ITWX20030003A1; DE10300477A1

Abstract

Described herein is a method of developing a system using virtual test, virtual trial and synthetic environment techniques. The method comprises a number of sequential stages (10, 12, 14, 16, 18) which interact with test processes (20, 22) to develop the system. In the first stage (10), a model of the system is defined in accordance with system requirement. The second stage (12) uses the model in a real-time synthetic environment to determine performance of the system which is compared with model performance. The next two stages (14,16) introduce hardware into the real-time virtual test, virtual trial and synthetic environment to assess its impact on performance of the system, the environment being capable of switching between software and hardware variables which are being assessed in the system. In the last stage (18), the system is assessed in a real trial environment and the resulting performance compared to model performance. In each sequential stage (10, 12, 14, 16, 18), the performance is processed by interactive processes (20, 22) as indicated by the arrows.

Description

A DEVELOPMENT AND TEST METHODOLOGY USING

SYNTHETIC ENVIRONMENTS

The present invention related to improvements in or relating to a development and test methodology using synthetic environments.

It is known to use synthetic environment tools for predicting the performance of a system under certain predetermined conditions. However, such tools tend to be utilised in the latter stages of development of the system when only a few elements of the system are yet to be finalised. This can result in substantial changes being made to the system at a stage when only minor changes are normally envisaged.

It is therefore an object of the present invention to utilise synthetic environment tools throughout the development of a new system to ensure that, at each stage of the development process, the system meets its design requirements.

In accordance with one aspect of the present invention, there is provided a method of developing a system using virtual test, virtual trial and synthetic environment techniques, the method comprising the steps of: a) defining a model of the system in accordance with system requirements; b) establishing a real-time synthetic environment in which variables of the system can be assessed; c) trialling variables in the system and comparing their performance with model performance; 2s d) using acceptable variable data from step c) as an input to a partial hardware implementation in the real-time synthetic environment, variables being assessed being implemented both in hardware and software such that the synthetic environment can switch between the two; - 2 e) trialling the variables of step d) and comparing their performance with model performance; Al conducting a trial scheme in a real environment having optimised the variables in hardware; and 9) comparing the performance of the trial scheme with model performance.

Advantageously, step e) includes trialling at least one variable in connection with equipment external to the real-time synthetic environment.

The method of the present invention has the advantage that early system integration can be achieved as virtual components and simulations are used in the synthetic environments. Moreover, as early phase integration is also achieved, the present invention also provides the ability to switch between 'real' and 'virtual' components of the system whilst still in a synthetic environment to allow the effect of each component on system perfommance to be fully assessed before full hardware implementation is completed.

Furthermore, in the assessment process, equivalent performance for the system can be determined at each stage in accordance with the system requirements to be met. This enables a system to be simulated, validated and verified prior to its full implementation in the shortest time possible.

It will be understood that synthetic environments are created as software and may interact with hardware if required. In the present invention, hardware is introduced into the synthetic environment as the development of the system progresses.

For a better understanding of the present invention, reference will now be z5 made, by way of example only, to the accompanying drawings in which: Figure 1 is a schematic block diagram of an integrated virtual trial environment in accordance with the present invention; and Figures 2 to 6 are respective schematic block diagrams of each stage of the trial environment of Figure 1.

Figure 1 illustrates an integrated virtual trial environment in accordance with the present invention. The environment comprises five sequential stages 10, 12, 14, 16, 18, (as indicated by the block arrows), a virtual trial process 20 and an equivalent performance process 22. Although five stages are illustrated in this specific embodiment of the invention, it will be appreciated that the present invention is not limited to five stages and may be carried out with more or less stages depending on the complexity of the system being developed.

Furthermore, stages may be combined where appropriate and utilise the same environment.

to As stages 10, 12, 14, 16, 18 are sequential stages, each of the following stages 12, 14, 16, 18 is only possible once the respective preceding stage 10, 12, 14, 16 has been satisfactorily completed. Virtual trial process 20 and equivalent performance process 22 are interactive processes, as indicated by the double headed arrows, and are utilised at each of the sequential stages 10, 12, 14, 16, 18 as will be described in detail below.

Virtual trial process 20 effectively tests the system under development, at each stage 10, 12, 14, 16, 18 and at each increment within a stage, in accordance with the equivalent performance process 22. This will be described in more detail below.

At the first sequential stage 10, a system model is developed in accordance with system requirements and performance metrics are determined which are stored in process 22 as the basis on which the equivalent performance of the system can be determined. Naturally, the performance metrics may be altered as development of the system progresses, and the new performance metrics stored in process 22.

After the system model has been defined in stage 10, it is trialied in virtual trial process 20 to ensure that performance requirements as compared to the performance metrics stored in equivalent performance process 22 have been met. If these are not met, adjustments are made to the model in stage 10 and the trial is repeated. This process is repeated until the performance requirements are met. Data is collected at each virtual trial process 20 in stage and compared with the performance metrics stored in process 22.

Once the system model is accepted at stage 10, that is, by meeting the performance requirements, the next sequential stage is reached. In stage 12, the software-in-the loop (SWIL) stage, a real-time synthetic environment is defined to simulate the system model defined in stage 10.

Once the synthetic environment (SE) has been defined, it is trialled in virtual trial process 20 to ensure that the performance requirements have been met. Again, any changes to variables of the system in the synthetic lo environment are re-trialled until the performance requirements set by process 22 are met, and it is possible to move onto sequential stage 14.

In stage 14, the hardware-on-the-bench (HWOB) stage, hardware is built up in phases within the synthetic environment to implement the SWIL SE defined in the previous stage. As before with the previous stages, the hardware is trialled and its equivalent performance determined in processes 20 and 22 respectively. The trialling carried out at this stage is static and the hardware is not fully operational. Again, any changes made to the hardware are re-trialed until they meet the performance requirements (processes 20 and 22), before moving on to stage 16.

Stage 16 is a dynamic phase and the system is trialled to test its dynamic capability possibly by interacting with equipment external to the synthetic environment. This stage is known as a hardware-in-the-loop (HWIL) stage.

As before, trialling with the interaction of processes 20 and 22 is carried out prior to moving onto the next stage.

Stage 18 is a real trial stage for the system and data obtained during this stage is used for analysis and evaluation with the information obtained and stored when executing the previous stages 10, 12, 14, 16. The data is also used in processes 20 and 22 to provide an indication of the correlation between the operation of the "virtual" or simulated system and the operation of the real system. - 5

By way of example only, the present invention will be described in more detail with reference to the development of a soft vertical launch missile system.

Naturally, the present invention can be utilised for the development of any system and is not limited to the development of soft vertical launch missile systems.

The object of a soft vertical launch system is to launch a missile from a vertical launch tube, change the translational motion of the missile from vertical to generally horizontal, fire thrusters and main motor to direct the missile to its target. Naturally, it will be appreciated that it would be impossible to organise a lo full trial at each stage of development due to lack of physical system components and the cost involved.

In the specific example of a virtual test, virtual trial and synthetic environment as shown in Figure 2 and corresponds to stage 10 of Figure 1, system requirements 28 for a subsystem are fed into the synthetic environment 30 to be able to define a model for the subsystem relating to the soft vertical launch system. In the synthetic environment 30, components 32, 34, 36, 38, 40, 42, 44 are defined for the operation of the missile from its stored stage, through launch, to its deployment stage. The components are relevant to the model of the system determined in accordance with the subsystem requirements or mission data (indicated by block 32), autopilot (block 34), the operation of motor and actuators (blocks 36 and 38 respectively), aerodynamics and kinematics (blocks 40 and 42 respectively) , and motion sensing (block 44).

As shown by the block arrows, these components interact with one another in specific ways, but this will not be discussed in detail as it is not relevant to the invention.

The term "mission" refers to the function the entire subsystem is to perform, for example, in this particular case, the launch of the missile and its subsequent directing to a target.

Output 46 from the synthetic environment 30 is evaluated by the analysis so 48, virtual trial 50, performance metrics 52, and visualise and assessment modes 54 modes. Output 46 may be combined with other outputs from other - 6 synthetic environments 56 to provide a more detailed evaluation if required.

The other synthetic environments 56 may relate to other subsystems (not shown).

Turning now to Figure 3, this corresponds to stage 12 of Figure 1. Here, the real-time software is defined as described above in a real-time synthetic environment 60. Components relevant to the subsystem previously discussed are referenced the same throughout this description and are not discussed again. This time the synthetic environment 60 is provided with the model and autopilot data or software for controlling the missile during launch (input 62).

to The mission data is now known (block 64) and is indicated by a dotted line box.

Similarly, the autopilot software (block 66) is also known and is indicated by a dotted line box. An output 68 is provided as before for evaluation. In this stage, the model performance 70 provides an input for relative performance mode 64 where the performance of the output 68 can be compared to that of the model defined in stage 10 (Figure 1).

Moving on to stage 14 as shown in Figure 4, the HWOB stage as described above, the real-time synthetic environment 80 is fed with the SWIL SE from stage 12 (Figure 3) and the autopilot software (indicated by 82). As before, the mission 64, (the SWIL SE in this case), and the autopilot software 66 are indicated by dotted line boxes. Here, the motion sensing 44 (Figure 2) and the actuators 38 (also Figure 2, are implemented as hardware or real components and retain their virtual forms to be able to evaluate the effect of the real components. This means that actuators 38 now comprise a real actuator 84 and a 'virtual' actuator 86 and the environment 80 can switch between the two as required. Similarly, motion sensing 44 now comprises a real sensor 88 and a 'virtual' sensor 90 and the environment 80 can switch between the two as required. Output 92 from SE 80 is processed as before.

The HWOB SE 100 is utilised in stage 16, the HWIL stage, as shown in Figure 5. Here, real-time synthetic environment 100 is supplied with the HWOB SE and autopilot software as indicated by 102. The real sensor 88 is mounted on a motion table 104 which is controlled by the kinematics 42 and the virtual' sensor 90 is removed. Output 106 from SE 100 is processed as before. - 7

The Anal stage is the trials stage as shown in Figure 6. Here the environment is a real trial environment 110 which includes a real sensor 88! a real actuator 84, an airframe 112 on which the sensor 88 is mounted and a flight recorder 114. The flight recorder 114 provides output 116 for evaluation as before. The trials data is stored in the flight recorder 114 and is only output after the trials have ended. This data is then evaluated and compared with the system model to determine if the model performance has been achieved. If model performance has not been met, the relevant variables are revised within the system and re-trialled. - 8

Claims

1. A method of developing a system using virtual test, virtual trial and synthetic environment techniques, the method comprising the steps of: a) defining a model of the system in accordance with system requirements; b) establishing a real-time synthetic environment in which variables of the system can be assessed; c) trialling variables in the system and comparing their performance with model performance; lo d) using acceptable variable data from step c) as an input to a partial hardware implementation in the real-time synthetic environment, variables being assessed being implemented both in hardware and software such that the synthetic environment can switch between the two; e) trialling the variables of step d) and comparing their performance with model performance; f) conducting a trial scheme in a real environment having optimised the variables in hardware; and 9) comparing the performance of the trial scheme with model performance.

2. A method according to claim 1, wherein step e) includes trialling at least one variable in connection with equipment external to the real-time synthetic environment.

3. A method of developing a system using virtual test, virtual trial and synthetic environment techniques substantially as hereinbefore described with reference to the accompanying drawings.