| 1. |
- Ejjeh, Adel, et al.
(författare)
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HPVM2FPGA: Enabling True Hardware-Agnostic FPGA Programming
- 2022
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Ingår i: IEEE 33rd International Conference on Application-specific Systems, Architectures and Processors (ASAP). - 9781665483087 - 9781665483094
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Konferensbidrag (refereegranskat)abstract
- Current FPGA programming tools require extensive hardware-specific manual code tuning to achieve performance, which is intractable for most software application teams. We present HPVM2FPGA, a novel end-to-end compiler and autotuning system that can automatically tune hardware-agnostic programs for FPGAs. HPVM2FPGA uses a hardware-agnostic abstraction of parallelism as an intermediate representation (IR) to represent hardware-agnostic programs. HPVM2FPGA’s powerful optimization framework uses sophisticated compiler optimizations and design space exploration (DSE) to automatically tune a hardware-agnostic program for a given FPGA. HPVM2FPGA is able to support software programmers by shifting the burden of performing hardware-specific optimizations to the compiler and DSE. We show that HPVM2FPGA can achieve up to 33× speedup compared to unoptimized baselines and can match the performance of hand-tuned HLS code for three of four benchmarks. We have designed HPVM2FPGA to be a modular and extensible framework, and we expect it to match handtuned code for most programs as the system matures with more optimizations. Overall, we believe that it constitutes a solid step closer to fully hardware-agnostic FPGA programming, making it a suitable cornerstone for future FPGA compiler research.
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| 2. |
- Hvarfner, Carl, et al.
(författare)
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Joint Entropy Search for Maximally-Informed Bayesian Optimization
- 2022
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Ingår i: Advances in Neural Information Processing Systems 35 (NeurIPS 2022).
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Konferensbidrag (refereegranskat)abstract
- Information-theoretic Bayesian optimization techniques have become popular for optimizing expensive-to-evaluate black-box functions due to their non-myopic qualities. Entropy Search and Predictive Entropy Search both consider the entropy over the optimum in the input space, while the recent Max-value Entropy Search considers the entropy over the optimal value in the output space. We propose Joint Entropy Search (JES), a novel information-theoretic acquisition function that considers an entirely new quantity, namely the entropy over the joint optimal probability density over both input and output space. To incorporate this information, we consider the reduction in entropy from conditioning on fantasized optimal input/output pairs. The resulting approach primarily relies on standard GP machinery and removes complex approximations typically associated with information-theoretic methods. With minimal computational overhead, JES shows superior decision-making, and yields state-of-the-art performance for information-theoretic approaches across a wide suite of tasks. As a light-weight approach with superior results, JES provides a new go-to acquisition function for Bayesian optimization.
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| 3. |
- Hvarfner, Carl, et al.
(författare)
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πBO: Augmenting Acquisition Functions with User Beliefs for Bayesian Optimization
- 2022
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Konferensbidrag (refereegranskat)abstract
- Bayesian optimization (BO) has become an established framework and popular tool for hyperparameter optimization (HPO) of machine learning (ML) algorithms. While known for its sample-efficiency, vanilla BO can not utilize readily available prior beliefs the practitioner has on the potential location of the optimum. Thus, BO disregards a valuable source of information, reducing its appeal to ML practitioners. To address this issue, we propose PiBO, an acquisition function generalization which incorporates prior beliefs about the location of the optimum in the form of a probability distribution, provided by the user. In contrast to previous approaches, PiBO is conceptually simple and can easily be integrated with existing libraries and many acquisition functions. We provide regret bounds when PiBO is applied to the common Expected Improvement acquisition function and prove convergence at regular rates independently of the prior. Further, our experiments show that BO outperforms competing approaches across a wide suite of benchmarks and prior characteristics. We also demonstrate that PiBO improves on the state-of-the-art performance for a popular deep learning task, with a 12.5 time-to-accuracy speedup over prominent BO approaches.
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| 4. |
- Kristoffersson Lind, Simon, et al.
(författare)
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Out-of-Distribution Detection for Adaptive Computer Vision
- 2023
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Ingår i: Image Analysis - 23rd Scandinavian Conference, SCIA 2023, Proceedings. - 1611-3349 .- 0302-9743. - 9783031314377 ; 13886 LNCS, s. 311-325
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Konferensbidrag (refereegranskat)abstract
- It is well known that computer vision can be unreliable when faced with previously unseen imaging conditions. This paper proposes a method to adapt camera parameters according to a normalizing flow-based out-of-distibution detector. A small-scale study is conducted which shows that adapting camera parameters according to this out-of-distibution detector leads to an average increase of 3 to 4% points in mAP, mAR and F1 performance metrics of a YOLOv4 object detector. As a secondary result, this paper also shows that it is possible to train a normalizing flow model for out-of-distribution detection on the COCO dataset, which is larger and more diverse than most benchmarks for out-of-distibution detectors.
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| 5. |
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| 6. |
- Mayr, Matthias, et al.
(författare)
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Learning of Parameters in Behavior Trees for Movement Skills
- 2021
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Ingår i: 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). - 9781665417150 - 9781665417143 ; , s. 7572-7572
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Konferensbidrag (refereegranskat)abstract
- Reinforcement Learning (RL) is a powerful mathematical framework that allows robots to learn complex skills by trial-and-error. Despite numerous successes in many applications, RL algorithms still require thousands of trials to converge to high-performing policies, can produce dangerous behaviors while learning, and the optimized policies (usually modeled as neural networks) give almost zero explanation when they fail to perform the task. For these reasons, the adoption of RL in industrial settings is not common. Behavior Trees (BTs), on the other hand, can provide a policy representation that a) supports modular and composable skills, b) allows for easy interpretation of the robot actions, and c) provides an advantageous low-dimensional parameter space. In this paper, we present a novel algorithm that can learn the parameters of a BT policy in simulation and then generalize to the physical robot without any additional training. We leverage a physical simulator with a digital twin of our workstation, and optimize the relevant parameters with a black-box optimizer. We showcase the efficacy of our method with a 7-DOF KUKAiiwa manipulator in a task that includes obstacle avoidance and a contact-rich insertion (peg-in-hole), in which our method outperforms the baselines.
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| 7. |
- Mayr, Matthias, et al.
(författare)
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Learning Skill-based Industrial Robot Tasks with User Priors
- 2022
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Ingår i: IEEE International Conference on Automation Science and Engineering (CASE). - 9781665490429 - 9781665490436 ; , s. 1485-1492
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Konferensbidrag (refereegranskat)abstract
- Robot skills systems are meant to reduce robot setup time for new manufacturing tasks. Yet, for dexterous, contact-rich tasks, it is often difficult to find the right skill parameters. One strategy is to learn these parameters by allowing the robot system to learn directly on the task. For a learning problem, a robot operator can typically specify the type and range of values of the parameters. Nevertheless, given their prior experience, robot operators should be able to help the learning process further by providing educated guesses about where in the parameter space potential optimal solutions could be found. Interestingly, such prior knowledge is not exploited in current robot learning frameworks. We introduce an approach that combines user priors and Bayesian optimization to allow fast optimization of robot industrial tasks at robot deployment time. We evaluate our method on three tasks that are learned in simulation as well as on two tasks that are learned directly on a real robot system. Additionally, we transfer knowledge from the corresponding simulation tasks by automatically constructing priors from well-performing configurations for learning on the real system. To handle potentially contradicting task objectives, the tasks are modeled as multi-objective problems. Our results show that operator priors, both user-specified and transferred, vastly accelerate the discovery of rich Pareto fronts, and typically produce final performance far superior to proposed baselines.
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| 8. |
- Mayr, Matthias, et al.
(författare)
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Skill-based Multi-objective Reinforcement Learning of Industrial Robot Tasks with Planning and Knowledge Integration
- 2022
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Ingår i: 2022 IEEE International Conference on Robotics and Biomimetics, ROBIO 2022. - 9781665481090 ; , s. 1995-2002
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Konferensbidrag (refereegranskat)abstract
- In modern industrial settings with small batch sizes it should be easy to set up a robot system for a new task. Strategies exist, e.g. the use of skills, but when it comes to handling forces and torques, these systems often fall short. We introduce an approach that provides a combination of task-level planning with targeted learning of scenario-specific parameters for skill-based systems. We propose the following pipeline: the user provides a task goal in the planning language PDDL, then a plan (i.e., a sequence of skills) is generated and the learnable parameters of the skills are automatically identified, and, finally, an operator chooses reward functions and parameters for the learning process. Two aspects of our methodology are critical: (a) learning is tightly integrated with a knowledge framework to support symbolic planning and to provide priors for learning, (b) using multi-objective optimization. This can help to balance key performance indicators (KPIs) such as safety and task performance since they can often affect each other. We adopt a multi-objective Bayesian optimization approach and learn entirely in simulation. We demonstrate the efficacy and versatility of our approach by learning skill parameters for two different contact-rich tasks. We show their successful execution on a real 7-DOF KUKA-iiwa manipulator and outperform the manual parameterization by human robot operators.
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| 9. |
- Nardi, Luigi, et al.
(författare)
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LassoBench: A High-Dimensional Hyperparameter Optimization Benchmark Suite for Lasso
- 2022
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Ingår i: Proceedings of Machine Learning Research. ; 188
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Konferensbidrag (refereegranskat)abstract
- While Weighted Lasso sparse regression has appealing statistical guarantees that would entail a major real-world impact in finance, genomics, and brain imaging applications, it is typically scarcely adopted due to its complex high-dimensional space composed by thousands of hyperparameters. On the other hand, the latest progress with high-dimensional hyperparameter optimization (HD-HPO) methods for black-box functions demonstrates that high-dimensional applications can indeed be efficiently optimized. Despite this initial success, HD-HPO approaches are mostly applied to synthetic problems with a moderate number of dimensions, which limits its impact in scientific and engineering applications. We propose LassoBench, the first benchmark suite tailored for Weighted Lasso regression. LassoBench consists of benchmarks for both well-controlled synthetic setups (number of samples, noise level, ambient and effective dimensionalities, and multiple fidelities) and real-world datasets, which enables the use of many flavors of HPO algorithms to be studied and extended to the high-dimensional Lasso setting. We evaluate 6 state-of-the-art HPO methods and 3 Lasso baselines, and demonstrate that Bayesian optimization and evolutionary strategies can improve over the methods commonly used for sparse regression while highlighting limitations of these frameworks in very high-dimensional and noisy settings.
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| 10. |
- Papenmeier, Leonard, et al.
(författare)
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Bounce: a Reliable Bayesian Optimization Algorithm for Combinatorial and Mixed Spaces
- 2023
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Ingår i: Advances in Neural Information Processing Systems, NeurIPS 2023.
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Konferensbidrag (refereegranskat)abstract
- Impactful applications such as materials discovery, hardware design, neural architecture search, or portfolio optimization require optimizing high-dimensional black-box functions with mixed and combinatorial input spaces. While Bayesian optimization has recently made significant progress in solving such problems, an in-depth analysis reveals that the current state-of-the-art methods are not reliable. Their performances degrade substantially when the unknown optima of the function do not have a certain structure. To fill the need for a reliable algorithm for combinatorial and mixed spaces, this paper proposes Bounce that relies on a novel map of various variable types into nested embeddings of increasing dimensionality. Comprehensive experiments show that Bounce reliably achieves and often even improves upon state-of-the-art performance on a variety of high-dimensional problems.
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