{"title":"Discrete-Time Transverse Feedback Linearization⋆","authors":"Rollen S. D’Souza","doi":"10.23919/ACC55779.2023.10156159","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156159","url":null,"abstract":"Applications of transverse feedback linearization (TFL) vary from path following mobile robots to vehicle formation control. These applications were restricted to systems adequately modelled in continuous-time. Recent work demonstrated that the established technique fails when applied to a discrete-time system using a zero-order hold. An additional change of coordinates dependent on the sampling period that preserves the required properties was proposed as an alternative. This technique, however, only applies to sampled-data systems. This article instead proposes a direct design approach that starts with a discrete-time system and designs a discrete-time transverse feedback linearizing controller. The discrete-time transverse feedback linearization problem is posed, and resolved for a single-input nonlinear discrete-time system. An example of path following for a forward-Euler discretized, kinematic unicycle model is presented to demonstrate its effectiveness.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121200803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Abramovitch, S. Andersson, K. Leang, W. Nagel, S. Ruben
{"title":"A Tutorial on Real-Time Computing Issues for Control Systems","authors":"D. Abramovitch, S. Andersson, K. Leang, W. Nagel, S. Ruben","doi":"10.23919/ACC55779.2023.10156102","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156102","url":null,"abstract":"This paper presents a tutorial on the elements of computation in a real-time control system. Unlike conventional computation or even computation in digital signal processing systems, computation in a feedback loop must be sensitive to issues of latency and noise around the loop. This presents some fundamental requirements, limitations, and design constraints not seen in other computational applications. The logic of presenting such a tutorial is that while the computer technology changes at a rapid pace, the principles of how we match that technology to the constraints of a feedback loop remain consistent over the years. We will discuss the different computational chains in a feedback system, ways to conceptualize the effects of time delay and jitter on the system, and present a three-layer-model for programming real-time computations. The tutorial also presents some filter and state-space structures that are useful for real-time computation. It concludes with an overview of the different sample rate ranges currently used in some typical control problems and a short discussion of how business models affect our choices in real-time computation.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114511117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
John W. Handler, M. Harker, G. Rath, Mathias Rollett
{"title":"Noniterative Model Predictive Control with Soft Input Constraints for Real-Time Trajectory Tracking","authors":"John W. Handler, M. Harker, G. Rath, Mathias Rollett","doi":"10.23919/ACC55779.2023.10156191","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156191","url":null,"abstract":"This paper develops a new approach to soft constrained model predictive control (MPC) for real-time trajectory tracking. The presented method does not rely on solving an iterative optimization algorithm at each sampling instance. In fact, the optimal control input is directly computed via an inner product of two vectors. This enables the computation of an optimal control input in real-time rather than having to use a suboptimal solution as is the case in most current real-time MPC approaches. The computational complexity of the presented method is linear w.r.t. the prediction horizon, state and input dimension, which makes it ideal for fast sampled, large systems. The functionality of the new approach is demonstrated in a laboratory setup of an underactuated, cranelike system. Furthermore, its performance is compared with a suboptimal MPC based on an active-set method with warmstart (ASM-MPC). It is shown that the new method is of the order of 105 times faster than the ASM-MPC, while achieving similar and in some cases even better tracking accuracy.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126233735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An introduction to learning in finite games","authors":"J. Shamma","doi":"10.23919/ACC55779.2023.10156273","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156273","url":null,"abstract":"In the setting of learning in games, player strategies evolve in an effort to maximize utility in response to the evolving strategies of other players. In contrast to the single agent case, learning in the presence of other learners induces a non-stationary environment from the perspective of any individual player. Depending on the specifics of the game and the learning dynamics, the evolving strategies may exhibit a variety of behaviors ranging from convergence to Nash equilibrium to oscillations to even chaos. This talk presents a basic introduction to learning in games through the presentation of selected results for finite normal form games, i.e., games with a finite number of players having a finite number of actions. The talk starts with a representative sample of learning dynamics that converge to Nash equilibrium for special classes of games. Specific learning dynamics include better reply dynamics, joint strategy fictitious play, and log-linear learning, with results for potential games and weakly acyclic games. These results apply to specifically pure Nash equilibrium. The talk also presents dynamics that address mixed/randomized strategy Nash equilibria, specifically smooth fictitious play and gradient play. The talk concludes with limitations in learning that stem from the notion of uncoupled dynamics, where a player’s learning dynamics cannot depend explicitly on the utility functions of other players.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127911612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vinícius Lima, D. Phan, Lam M. Nguyen, J. Kalagnanam
{"title":"Optimal Control via Linearizable Deep Learning","authors":"Vinícius Lima, D. Phan, Lam M. Nguyen, J. Kalagnanam","doi":"10.23919/ACC55779.2023.10155810","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10155810","url":null,"abstract":"Deep learning models are frequently used to capture relations between inputs and outputs and to predict operation costs in dynamical systems. Computing optimal control policies based on the resulting regression models, however, is a challenging task because of the nonlinearity and nonconvexity of deep learning architectures. To address this issue, we propose in this paper a linearizable approach to design optimal control policies based on deep learning models for handling both continuous and discrete action spaces. When using piecewise linear activation functions, one can construct an equivalent representation of recurrent neural networks in terms of a set of mixed-integer linear constraints. That in turn means that the optimal control problem reduces to a mixed-integer linear program (MILP), which can then be solved using offthe-shelf MILP optimization solvers. Numerical experiments on standard reinforcement learning benchmarks attest to the good performance of the proposed approach.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115884664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dynamics and Control of AUVs using Buoyancy-Based Soft Actuation","authors":"C. Hoppe, F. Ghorbel, Zheng Chen","doi":"10.23919/ACC55779.2023.10156334","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156334","url":null,"abstract":"Nonlinear control of Autonomous Underwater Vehicles (AUVs) via the use of thrusters has been well established. These AUVs can be used for various applications, including subsea inspection and maintenance, exploration, research, and observation. These thrusters are best suited for large thrust forces required by large movements, but require a lot of energy to operate for long periods of time. Research into Buoyancy Control Devices (BCDs) using reversible fuel cells (RFCs) has proven their viability. This paper demonstrates nonlinear control of BCD–based AUVs while picking up tools with unknown weights. An adaptive control law is derived that ensures stability and good performance throughout the completion of the desired mission. Simulation results demonstrate desired performance with low energy requirements.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132511825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"LSTM-based control of cellulose degree of polymerization in a batch pulp digester","authors":"Parth Shah, Hyun-Kyu Choi, J. Kwon","doi":"10.23919/ACC55779.2023.10156480","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156480","url":null,"abstract":"Due to ever increasing demand for different types of paper, it is crucial to optimize the Kraft pulping process to achieve the required paper properties. This work proposes a framework to regulate these paper properties by building a novel closed-loop long short-term memory (LSTM)-based model predictive control system. First, a multiscale model was developed by combining the mass and thermal energy balance equations adopted from Purdue model with a layered kinetic Monte Carlo (kMC) algorithm that describes the time-evolution of microscopic events such as fiber morphology, kappa number, and cellulose Degree of Polymerization (DP). Then, this model was run over different operating conditions by varying the temperature, concentration, and cooking time to generate data. An LSTM-ANN network was trained using these datasets with a prediction accuracy of over 98% capturing the behavior of cellulose DP and considering the effects of time-varying and time-invariant operating conditions together. Finally, a closed-loop LSTM-based optimal controller was designed, which was demonstrated to achieve the target set-point values and obtain optimal constant value inputs along with time-series inputs while considering process constraints. The results showed excellent accuracy and the controller was computationally less expensive due to the use of a well-trained LSTM network in the proposed framework.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"221 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131653268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Trade-offs in the Design of Multi-Loop Controllers for Floating Wind Turbines","authors":"David Stockhouse, L. Pao","doi":"10.23919/ACC55779.2023.10156143","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156143","url":null,"abstract":"Feedback control of land-based wind turbines is well-established in both industry and academia, however, the same control strategies do not necessarily perform well when applied to floating offshore wind turbines (FOWTs). Multi-loop feedback has been investigated to address the challenges of FOWT control, but the various proposed auxiliary feedback architectures are seldom compared under a unified study. Four multi-loop control approaches are analyzed in this work and evaluated for their ability to improve FOWT performance metrics, including power quality, generator-speed tracking, and structural loading. Each control law is analyzed in the context of closed-loop system stability using root locus methods and tuned using a frequency-based stability margin. The controllers are evaluated using the nonlinear aero-servo-hydro-elastic simulation tool OpenFAST to validate performance benefits compared to a single-loop baseline controller.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131724008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Binh Nguyen, Truong X. Nghiem, Linh Nguyen, Tung Nguyen, Hung M. La, Mehdi Sookhak, Thang Nguyen
{"title":"Distributed formation trajectory planning for multi-vehicle systems","authors":"Binh Nguyen, Truong X. Nghiem, Linh Nguyen, Tung Nguyen, Hung M. La, Mehdi Sookhak, Thang Nguyen","doi":"10.23919/ACC55779.2023.10156635","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156635","url":null,"abstract":"This paper addresses the problem of distributed formation trajectory planning for multi-vehicle systems with collision avoidance among vehicles. Unlike some previous distributed formation trajectory planning methods, our proposed approach offers great flexibility in handling computational tasks for each vehicle when the global formation of all the vehicles changes. It affords the system the ability to adapt to the computational capabilities of the vehicles. Furthermore, global formation constraints can be handled at any selected vehicles. Thus, any formation change can be effectively updated without recomputing all local formations at all the vehicles. To guarantee the above features, we first formulate a dynamic consensus-based optimization problem to achieve desired formations while guaranteeing collision avoidance among vehicles. Then, the optimization problem is effectively solved by ADMM-based or alternating projection-based algorithms, which are also presented. Theoretical analysis is provided not only to ensure the convergence of our method but also to show that the proposed algorithm can surely be implemented in a fully distributed manner. The effectiveness of the proposed method is illustrated by a numerical example of a 9-vehicle system.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"355 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127582524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kristina Miller, J. Brewer, Alexander A. Soderlund, S. Phillips
{"title":"Sensor Safety and Multi-Objective Satellite Control under Nonlinear Dynamics","authors":"Kristina Miller, J. Brewer, Alexander A. Soderlund, S. Phillips","doi":"10.23919/ACC55779.2023.10156074","DOIUrl":"https://doi.org/10.23919/ACC55779.2023.10156074","url":null,"abstract":"The safe operation of satellites is critical as the space domain becomes more cluttered with resident objects. Controller synthesis is a technique used to automatically generate correct-by-construction controllers that guarantee a system will satisfy some requirements, such as safety. In this work, we cast the safe satellite operation problem as a controller synthesis problem, and propose an algorithm that synthesizes full-state control of a satellite. This is done by decoupling the translational control from the attitude control. We deploy this algorithm in a close-proximity scenario and show that the synthesized controller satisfies our requirements and guarantees the safety of a chaser satellite.","PeriodicalId":397401,"journal":{"name":"2023 American Control Conference (ACC)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129375148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}