CPU Model-Based Mechatronics/Hardware/Software Co-design Technology for Real-Time Embedded Control Systems

<div class="htmlview paragraph">This paper proposes a new development method for highly reliable real-time embedded control systems using a CPU model-based hardware/software co-simulation. We take an approach that allows the full simulation of the virtual mechanical control system including CPU and object code level software. In this paper, Renesas SH-2A microcontroller model was developed on CoMET™ platform from VaST Systems Technology. A ETC (Electronic Throttle Control) system and engine control system were chosen to prove this concept. The ETB (Electronic Throttle Body) model on Saber<sup>®</sup> simulator from Synopsys<sup>®</sup> or engine model on MATLAB<sup>®</sup>/Simulink<sup>®</sup> simulator from MathWorks can be simulated with the SH-2A model. To help the system design, debug and evaluation, we developed an integrated behavior analyzer, which can display CPU behavior graphically during the simulation without affecting the simulation result, such as task level CPU load, interrupt statistics, software variable transition chart, and so on. The software has not been modified for this virtual system analysis. This analyzer provides useful information what happens in the system and it should be system HW/SW debugging tools for hard real-time control system. The SH-2A chip was under development during this project, nevertheless we could complete the OSEK OS development, control software design and verification. We already confirmed that this software could run on an actual ETC hardware system without modification after working sample chip released.</div>

Electronic throttle control (ETC) system has worked its way to becoming a standard subsystem in most of the current automobiles as it has contributed much to the improvement of fuel economy, emissions, drivability and safety. Precision control of the subsystem, which consists of a dc motor driving a throttle plate, a pre-loaded return spring and a set of gear train to regulate airflow into the engine, seems rather straightforward and yet complex. The difficulties lie in the unknown system parameters, hard nonlinearity of the pre-loaded spring that pulls the throttle plate to its default position, and friction, among others. In this paper, we extend our previous results obtained for the modeling, unknown system parameters identification and control of a commercially available Bosch’s DV-E5 ETC system. Details of modeling and parameters identification based on laboratory experiments, data analysis, and knowledge of the system are provided. The parameters identification results were verified and validated by a real-time PID control implemented with an xPC Target. A nonlinear control design was then proposed utilizing the input-output feedback linearization approach and technique. In view of a recent massive auto recalls due to the controversial uncontrollable engine accelerations, the results of this paper may inspire further research interest on the drive-by-wire technology.

Nowadays, electronic throttle control system is widely adapted in the motorcycle for better drivability, fuel economy and reduces the emissions. In such systems, pedal follower or torque based approach are used for calculating the required throttle angle for the given torque demand by driver. This work presents a throttle control system for the precise estimation of throttle angle based on the integrated pedal follower and torque based approach for the given accelerator position and torque demand by the driver. A mathematical model for an electronic throttle body is developed to understand the effects of nonlinearities due to friction and limp home dual springs. A PID controller with compensators are developed to handle the nonlinearities due to the friction and limp home dual springs in the proposed electronic throttle control system. A simulation study has been carried out using software in loop and hardware in loop simulation approaches for step, sinusoidal, and ramp input signals. The responses of electronic throttle body for opening the throttle angle and error are analyzed for the given input signals. The simulation result shows that the proposed compensators has significant advantage in reducing the throttle angle error and gives the desired output.

This practice paper examines Toyota's electronic throttle controller (ETC) problem. ETC for passenger cars is a safety-critical, embedded control system and it must meet very high reliability and safety requirements. ETC systems continue to increase in complexity, making formal specification and verification processes an essential component of the development of safer systems. There are two ways to represent the real-time system. Firstly, we can describe the system's structure and function by detailing its electrical, mechanical, and other components. Secondly, the real-time system's behavior as it responds to actions and events can be described. Then we can compare the system's specification to the safety assertion to show that the system meets the safety properties. This paper describes two research threads. In the first, we present the specification of Toyota's electronic throttle control (ETC) system including the timing constraints. The second thread, which will be explored in a longer version of this paper, evaluates the use of conventional design versus electronic engine control by applying classical control theory.1

Due to some nonlinear factors and time delay in electronic throttle, the opening of electronic throttle is difficult to control. For overcoming these difficulties, in this paper a fuzzy adaptive PID controller is designed for an electronic throttle control system. The model of electronic throttle control system is built based on Matlab/Simulink and realized with a hardware-in-the-loop simulation system, which is based on MACS565. Simulation research and experiment results show that, compared with PID control system, the fuzzy adaptive PID control system, has some advantages. The all performance index with the fuzzy adaptive PID control is better than that of the PID control.

Abstract: Brusoni, Prencipe, and Pavitt (2001) posited that the digitization of aircraft engine control systems in the early 1980s caused loose organizational coupling. During this period, the number of control parameters indeed increased significantly with the introduction of full authority digital engine control (FADEC). However, during the period categorized by Brusoni et al. (2001) as the (analog) generation, digital technologies such as analog electronic and supervisory controls were gradually introduced. Moreover, with regard to technological changes in aircraft turbofan engines and control systems, technological improvements in engine power systems were evident in the 1960s and 1970s in terms of the bypass ratio, overall pressure ratio, and turbine inlet temperature. Although engine power systems witnessed negligible technological innovation in the 1980s, control systems improved as the number of control parameters increased due to the advent of FADEC. Subsequently, in the 1990s, great technological strides were made in engine power systems. Hence, technological changes in engine power systems and control systems always occurred alternately. Brusoni et al.'s claim that the decline in organizational coupling was due to the even rate of technological change in engines and control systems or the predictability in their interdependence miss the mark in light of the transition history of engine and control systems.Keywords: analog (hydromechanical), digital, aircraft engine control system, technological imbalance1. IntroductionBrusoni, Prencipe, and Pavitt (2001) categorized aircraft engine control systems from the 1950s to the 1970s as hydromechanical (analog) and those from the 1980s to the 1990s as digital. Brusoni et al. (2001) described the scope for change in the organizational structure and knowledge of three companies1 from the perspective of the evolution of control system technology. However, they barely mentioned the change in control system technology from analog to digital, nor did they focus on the changes in the engine power systems, which are associated with changes in control system technology. Referencing Brusoni et al.'s arguments, this study focuses on the transition of engine control systems from analog to digital and the associated technological changes in the power systems in order to review the technologies analyzed by Brusoni et al.2. Technological Change of Engine Control System:From Hydromechanical to DigitalBrusoni et al. (2001) focused on the control systems of aircraft turbofan and turbojet engines. A turbojet engine comprises an air intake, a fan/compressor, combustion chamber, turbine, afterburner, and tail nozzle. The pilot adjusts the position of the throttle lever to achieve the required thrust. The engine control system provides the necessary thrust by receiving the lever position as input and adjusting the fuel flow, thereby accelerating or decelerating the engine's revolutions per minute (RPM). Furthermore, it confirms whether the thrust corresponds with the pilot's intention and maintains the required thrust levels (Yoshinaka, 2010).Compared with the digital system, the analog system could control only a limited number of items. The following section discusses the evolution of jet engine control technologies based on Endoh (2004), Sugiyama (2004), Sono (2008), and Yoshinaka (2010).2.1. Hydromechanical controlThe jet engine was first adopted as a source of thrust in aircrafts in the 1930s. Simple mechanical fuel controls comprising cams and levers were used in reciprocating engines, which constituted the majority at the time. The control required by jet engines was comparatively complex, and the existing technology was inadequate. Even in the case of early post-war turbojet engines, variables of fuel flow or bleed valve could only be controlled. Subsequently, advances in the level of precision and miniaturization in the areas of mechanics and oil hydraulics led to progress in the control technologies of aircraft engines. …

The model-based methodology has proven to be effective for fast and low-cost development of embedded software In the model-based development process, transforming a software structural model that describes the underlying application, to an implementable runtime model is a critical issue. Since the designed software will finally run on the target platform, non-functional issues like schedulability, timing constraints and resource requirements have to be considered during the transformation. In this paper, we propose a generic runtime model architecture that can best satisfy the non-functional requirements of the system, and a generic transformation method to convert a structural model to a runtime model in such an architecture. The transformation approach is based on the notion of end-to-end computations performed by the system in response to external stimuli. We demonstrate the advantages and effectiveness of the proposed method by constructing a software runtime model for a combined electronic throttle and air-fuel ratio control system.

This paper describes the characteristics of Electronic Throttle Controller (ETC) module in BLDC motor without the hall sensor for detecting a rotor position. The proposed ETC control system, which is mainly consisted of a BLDC motor, a throttle plate, a return spring and reduction gear, has a position sensor with an analogue voltage output on the throttle valve instead of BLDC motor for detecting the rotor position. So the additional commutation information is necessarily needed to control the ETC module. For this, the estimation method is applied. In order to improve and obtain the high resolution for the position control, it is generally needed to change the gear ratio of the module or the electrical switching method etc. In this paper, the 3-phase switching between successive commutations is adapted instead of the 2-phase switching that is conventionally used. In addition, the position control with a variable PI gain is applied to improve a dynamic response during a transient period and reduce vibration at a stop in case of matching position reference. The mentioned method can be used to estimate the commutation state and operate the high-precision position control for the ETC module and the high response characteristics. The validity of the proposed method is examined through the experimental results.

<div class="htmlview paragraph">A new 2.0 <i>ℓ</i> DOHC 4-valve direct injection (DI) gasoline engine has been developed which features new technologies such as swirl intake ports to produce an optimum swirl in the cylinder by variable controlled swirl control valve, pistons with a concave combustion chamber, and high pressure fuel injection system to provide a fine fuel-air mixture cloud in the combustion chamber. These all help to control fuel-air mixture preparation and flame propagation under ultra lean, stratified combustion at partial loads. NOx emission is reduced by using an electrically controlled EGR system and an NOx storage-reduction catalyst. At higher loads, a homogeneous mixture is obtained with direct injection during the intake stroke. A seamless output torque transition between stratified charge and homogeneous charge condition is achieved by an electronic throttle control system.</div> <div class="htmlview paragraph">It has been confirmed that a vehicle with this system successfully improves fuel economy while satisfying emission requirements.</div>

A nonlinear hybrid electric vehicle (HEV), taken as a challenge due to its uncertainty in speed control, is controlled using cascade control loop of FO-PI (Fractional order PI) and FO-PD (Fractional order PD) controllers in this research. HEVs have a combination of mechanical and electrical subsystems arranged in cascade configuration. Mechanical subsystem consists of dynamics of vehicles and electrical subsystem comprises of Electronic Throttle Control System (ETCS). The other controllers evaluated are fractional order PID (FOPID), classical PID and PI cascaded with PD (PI-PD). The gains of the proposed and other controllers are tuned by Particle Swarm optimisation algorithm (PSO). Performance is examined for tracking of speed profile trajectory, rejection of disturbance phenomenon. Different performance parameters such as IAE (Integral of Absolute Error), OS (Overshoot), Rise time, Settling time are measured for examining behaviour of different controllers designed for controlling the speed of HEVs. The IAE of FOPI-FOPD tuned by PSO is 17.077 is least amongst the IAE of FOPID, PI-PD, PID tuned by PSO with values 22.771, 25.250, 29.134 respectively for set point tracking profile. The results show that FOPI-FOPD controller tuned by PSO has superior performance as compared to other competitive controllers in controlling the speed of HEVs.

<div class="htmlview paragraph">The ongoing advances being made in electronics technology has made it possible to expand the range of microcomputer applications in automotive engine control systems. Progress in this field of application has given rise to very sophisticated control systems called total engine control systems, which are designed to provide interacting control with other subsystems (e.g., antiskid braking system, traction control system, transmission control system), instead of just controlling the engine itself. Improved engine control system performance and more versatile functions have made the application software controlling the system larger, with more complex control processing.</div> <div class="htmlview paragraph">Until now, control processing in engine control systems could be implemented by the microcomputer's interrupt processing program alone. However, because engine control systems have grown in both size and complexity, it has become difficult to determine the sequence in which processing programs (tasks) are to be executed. Consequently, the basic software (realtime operating system) that efficiently makes this determination has become necessary.</div> <div class="htmlview paragraph">This paper describes the use of microcomputers in engine control systems by using our newly developed μPD78602 16-Bit Single-Chip Microcomputer that incorporates a realtime operating system as firmware (alias Realtime Task Manager: RTM) as an example.</div>

Model-based development (MBD), which utilizes system models to design complex products, has received increasing attention. However, an advanced control system design scheme is required to accurately control the developed products under harsh conditions for practical usage. This paper proposes a control system that integrates a data-driven compensator (DDC) with a model-based control (MBC) system design. The proposed method considers a hierarchical control structure comprising an upstream control system based on the MBC design approach and a downstream control system that includes a plant control loop with a DDC. The proposed system can always maintain the desired performance by driving the MBC based on an ideal model because the downstream control system, DDC, maintains the characteristics of the ideal model even if the plant properties change owing to changes in operational and/or environmental conditions. In this study, the design scheme for unifying models and data in the MBD process is called smart MBD (S-MBD), and the proposed control system design scheme is based on the S-MBD approach. The effectiveness of the proposed hierarchical control system is verified by applying it to a hydraulic excavator.

Distributed control architecture can bring many benefits to the engine control system, but the delay and packet dropout introduced by network communication will bring negative effects to the control system. The aging and deterioration of the engine are also obstacles in the design of the engine control system. This paper is concerned with the problem of guaranteed cost control for a distributed engine control system (DECS) with these negative constraints. Firstly, a model of DECS with multiple delays, packet dropouts and uncertainties is built. Secondly, a multiple delay-dependent guaranteed cost controller design method is proposed in the form of a set of linear matrix inequalities (LMIs). The non-convex optimal controller design problem is transformed into a convex optimization problem through the cone complementarity linearization (CCL) method, and the suboptimal controller is designed iteratively. Thirdly, turboshaft engine aging and deterioration are treated as sources of uncertainties, and the norm-bounded uncertain model of the turboshaft engine is modeled. Finally, the numerical simulations demonstrate the effectiveness and applicability of the guaranteed cost controller designed for DECS with multiple delays, packet dropouts, engine aging and deteriorations.

The object of research is an electronic microprocessor control system for gas internal combustion engines with spark ignition for operation on liquefied petroleum gas. The system consists of two main subsystems, the accumulative power supply common rail LPG injection subsystem and the contactless electronic ignition subsystem with a movable voltage distributor. In addition, the control system also includes a subsystem for controlling the filling of the cylinders with the charge of the working mixture, consisting of a throttle valve and an idle speed regulator with a conical damper. The control system, depending on the software version, is capable of providing group or sequential injection of liquefied petroleum gas into the inlet pipe of each cylinder in the area close to the inlet valve. Such a control system can be used when converting (re-equipping) both new diesel engines into spark-ignition gas engines, and those that are in operation. The feasibility of such a conversion is to reduce operating costs with powerful vehicles for diesel fuel, by replacing it with cheaper and environmentally friendly liquefied petroleum gas.To test the efficiency of the control system, a D-240-LPG-«B» model gas engine was developed and manufactured to operate on liquefied petroleum gas. The gas engine was converted on the basis of the D-240 transport diesel engine (atmospheric, four-stroke, liquid-cooled, 4-cylinder engine with a piston diameter of 110 mm and a stroke of 125 mm). Reducing the compression ratio of the diesel engine was achieved by modifying a semi-closed diesel combustion chamber of the TsNIDI type into an open combustion chamber in the form of an axisymmetric «truncated cone». For efficient control of three subsystems of the D-240-LPG-«B» model gas engine, an electronic microprocessor control unit of the Avenir Gaz 37 «B» model was developed and manufactured. The tests carried out on the D-240-LPG-«B» gas engine with the Avenir Gaz 37 «B» control unit showed the efficiency of using the electronic microprocessor control system.

Future gas turbine engine control systems will be based on a distributed architecture in which the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) system is dependent on the network performance. The network-induced time delay may degrade the performance of the closed-loop systems and even destabilize the systems if the controllers are designed without considering the effects of the delay. This paper introduces a new method to estimate the maximum tolerance of the time delay for analysis of the stability of the GE T700 turboshaft engine DEC system. The sufficient conditions for stability are derived and dynamic output feedback controllers for the turboshaft engine are applied. Hardware-in-the-loop simulation illustrates the effectiveness of the presented method.