Nader Ben Amor

Design of a multimedia processor based on metrics computation

Media-processing applications, such as signal processing, 2D and 3D graphics rendering, and image compression, are the dominant workloads in many embedded systems today. The real-time constraints of those media applications have taxing demands on todays processor performances with low cost, low power and reduced design delay. To satisfy those challenges, a fast and efficient strategy consists in upgrading a low cost general purpose processor core. This approach is based on the personalization of a general RISC processor core according the target multimedia application requirements. Thus, if the extra cost is justified, the general purpose processor GPP core can be enforced with instruction level coprocessors, coarse grain dedicated hardware, ad hoc memories or new GPP cores. In this way the final design solution is tailored to the application requirements. The proposed approach is based on three main steps: the first one is the analysis of the targeted application using efficient metrics. The second step is the selection of the appropriate architecture template according to the first step results and recommendations. The third step is the architecture generation. This approach is experimented using various image and video algorithms showing its feasibility.

Self adaptive reconfigurable system based on middleware cross layer adaptation model

The emergence of mobile multimedia systems and the diversity of the supported multimedia applications put new challenges for their design. These systems must provide a maximum application quality of service (QoS) in the presence of a dynamically varying environment (e.g. video streaming and multimedia conferencing) and multiple resources constraints (e.g. remaining energy). To respond to the changing resource availability and application demands, a new class of adaptation method is emerged. It combines the adaptation simultaneously upon the different layers related to the target system. This paper presents a framework dedicated for mobile multimedia systems. It supports application QoS under real time and lifetime constraints via coordinated adaptation in the hardware, OS, and application layer. In this framework, we present a new middleware approach based on a global and a local manager. The global manager (GM) is used to handle large and long-term variations whereas the local manager (LM) is used to guarantee the real time constraint. The GM intervenes in three layers but the LM intervenes only in the application layer and OS layer. We have implemented this approach on reconfigurable platform using Altera technology.

Self-adaptive on-chip system based on cross-layer adaptation approach

The emergence of mobile and battery operated multimedia systems and the diversity of supported applications mount new challenges in terms of design efficiency of these systems which must provide a maximum application quality of service (QoS) in the presence of a dynamically varying environment. These optimization problems cannot be entirely solved at design time and some efficiency gains can be obtained at run-time by means of self-adaptivity. In this paper, we propose a new cross-layer hardware (HW)/software (SW) adaptation solution for embedded mobile systems. It supports application QoS under real-time and lifetime constraints via coordinated adaptation in the hardware, operating system (OS), and application layers. Our method relies on an original middleware solution used on both global and local managers. The global manager (GM) handles large, long-term variations whereas the local manager (LM) is used to guarantee real-time constraints. The GM acts in three layers whereas the LM acts in application and OS layers only. The main role of GM is to select the best configuration for each application to meet the constraints of the system and respect the preferences of the user. The proposed approach has been applied to a 3D graphics application and successfully implemented on an Altera FPGA.

A HW/SW implementation on FPGA of a robot localization algorithm

This paper presents an implementation of robot localization algorithm using FPGA technology. The adopted localization method uses webcam tracking images. This technique has been developed and implemented for the motion of the robot from an initial position towards another desired position. Firstly, we have validated our approach on PC platform using C language and OpenCV library. Secondly, for the autonomous navigation, a mixed HW/SW implementation was been developed using a high performance version of the NIOS processor coupled with a hardware accelerator. Experimental tests on Altera Cyclone III FPGA Starter Kit proved the effectiveness of the proposed architecture.

Virtual prototyping of multiprocessor architectures using the open virtual platform

The complexity of System on Chip (SoC) design is increasing continuously with the use of MultiProcessor System on Chip (MPSoC) architectures. Mastering the complexity of these systems with a typical co-design workflow is really recommended. As such, computer aided design tools are needed to alleviate the task of designers. There is a lack of co-design tools that support multiprocessor architectures with Operating System (OS) support. Virtual platforms enable us to discover the interactive design space exploration at early stage in the design. They make designing embedded systems less tedious and elevate the low technical details to manage systems complexity and reduce time to market. In this paper, we present an exploration of the Open Virtual Platform (OVP) capabilities for multiprocessor architectures simulation. We particularly focus on the inter-processor communication facilities. We illustrate this study by a set of homogeneous and heterogeneous multiprocessor architectures with different memory hierarchies and peripherals followed by a run of several applications. We also integrate the use of OS to permit workload distribution among processors using several case studies to validate our system.

Remote control of mobile robot through 3D virtual reality environment

This paper describes teleoperation systems for remote control of robot and the use of 3D virtual reality. It presents the adopted architecture and describes the experimental implementation through simulation results for mobile robot Khepera.

A timing constraints control technique for embedded real time systems

The real-time applications have a growing complexity and size which have to be well controlled. They can be viewed as a set of synchronized tasks, communicating and sharing critical resources. One of the main difficulties in the real-time application design is time constraints meeting. All tasks have to be running before their predefined deadlines. At this level, the integration of real time operating systems (RTOS) in the real-time systems design flow is necessary to enable scheduling tasks and managing the competition between them with respect of timing constraints. One of the problems encountered here is that one task may have different execution times. It may exceed its predefined WCET and then its deadline for many reasons. The problem is that one deadline exceeding may cause subsequent constraints violations which may disrupt the functioning of the system. This paper deals with this particular issue. It presents a new technique that permits the monitoring of tasks under execution. It controls their timing constraints by means of watchdog concept and detects deadline missing. That information is used to tune the target application parameters in order to satisfy timing constraints for the further computation iterations. We have implemented this technique in the RTOS MicroC/OS-II using the EDF scheduling policy. This technique has been validated using an Altera FPGA prototyping platform and the 3D rendering application.

Autonomous mobile robot navigation coupling fuzzy logic and reactive DVZ 3D obstacle avoidance control

This paper deals with the reactive control of an autonomous mobile robot which should move safely in a unknown three-dimensional(3D) environment to reach a desired goal. In order to proceed with the problem, we propose a hybrid approach based on fuzzy logic controller (FLC) for goal seeking behavior and Deformable Virtual Zone (DVZ) reactive algorithm to address 3D obstacles avoidance. We suggest a practical solution to combine both controllers. The proposed approach has been successfully tested in different configuration on simulation.

Proof of concept of a PIC wireless programmer interface for prototyping

In the near future, computers will be embedded everywhere and the Ubiquitous computing will be widely used. Ubiquitous computing requires multidisciplinary knowledge. To design such systems, a specific heterogeneous prototyping platform is required. Such platform has to be sufficiently versatile and in the same time easy to program even for beginners. Most ubiquitous systems are microcontrollers-based and are already too hard to program, limiting therefore their flexibility. In this paper we present a new concept of an easy to use wireless prototyping platform for Ubiquitous Computing suitable for people with limited computer skills. The prototype realized in this paper consists of a PIC that interfaces a Bluetooth USB dongle to communicate with the computer and send the program file to the targeted PIC to program it in place and from a distance.

OS service update for an online adaptive embedded multimedia system

The increasing popularity of nomad multimedia systems put new challenges for their design: increasing functionalities, limited energy and computation resources. These systems must provide a maximum application quality of service (QoS) in the presence of a dynamically varying environment (e.g. video streaming and multimedia conferencing) and multiple resources constraints. To respond to the changing resource availability and application demands, a new class of adaptation method is emerged. It combines the adaptation simultaneously upon the dirrerent layers related to the target system: hardware, application and OS. This paper presents an overview of a multilayer. The global manager (GM) is uses to handle large and long-term variations whereas the local manager (LM) is used to guarantee the real time constraint. This paper focuses on the LM that intervenes only in the application layer and OS layer.