Energy Reduction of Robot Stations with Uncertainties

This thesis aims to present a practical approach to reducing the energy use of industrial robot stations. The starting point of this work is different types of robot stations and production systems found in the automotive industry, such as welding stations and human-robot collaborative stations, and the aim is to find and verify methods of reducing the energy use in such systems. Practical challenges with this include limited information about the systems, such as energy models of the robots; limited access to the stations, which complicates experiment and data collection; limitations in the robot control system; and a general reluctance by companies to make drastic changes to already tested and approved production systems. Another practical constraint is to reduce energy use without slowing down production. This is especially challenging when a robot station contains stochastic variations, which is the case in many practical applications. Motivated by these challenges, this thesis presents an offline method of reducing the energy use of a production line of welding stations in an automotive factory. The robot stations contain stochastic uncertainties in the form of variations in the robot execution times, and the energy use is reduced by limiting the robot velocities. The method involves collecting data, modeling the system, formulating and solving a nonlinear and stochastic optimization problem, and applying the results to the real robot station. Tests on real stations show that, with only small modifications, the energy use can be reduced significantly, up to 24 percent.The thesis also contains an online method of controlling a collaborative human-robot bin picking station in a robust and energy-optimal way. The problem is partly a scheduling problem to determine in which orders the operations should be executed, and a timing problem to determine the velocities of the robots. A particular challenge is that some model parameters are unknown and have to be estimated online. A multi-layered control algorithm is presented that continuously updates the operation order and tunes the robot velocities as new orders arrive in the system. Simultaneously, a reinforcement learning algorithm is used to update estimates of the unknown parameters to be used in the optimization algorithms

Energy reduction of stochastic time-constrained robot stations

This paper looks at the problem of reducing the energy use of robot movements in a robot station with stochastic execution times, while keeping the productivity of the station. The problem is formulated as a stochastic optimization problem, that constrains the makespan of the station to meet a deadline with a high probability. The energy use of the station is a function of the execution times of the robot operations, and the goal is to reduce this energy use by finding the optimal execution times and operation order. A theoretical motivation to why the stochastic variables in the problem, under some conditions, can be approximated as independent and normally distributed is presented, together with a derivation of the max function of stochastic variables. This allows the stochastic optimization problem to be approximated with a deterministic version, that can be solved with a commercial solver. The accuracy of the deterministic approximation is evaluated on multiple numerical examples, which show that the method successfully reduces the energy use, while the deadlines of the stations are met with high probabilities

Fysioterapeuters syn på orsaker till skador samt hur dessa kan förebyggas, inom svensk elitfotboll - en intervjustudie

Bakgrund: Fotboll är en av världens största idrotter och står för en stor del av alla sportrelaterade skador. Skadorna kan leda till nedsatt hälsa, kostnader för samhället samt slutet av en spelarkarriär. Hittills har forskningen främst fokuserats på träning när det gäller skadeförebyggande åtgärder. Det finns även andra faktorer som kan minska skaderisken men som i dagsläget inte utforskats i samma utsträckning. Syfte: Syftet var att undersöka uppfattningar och erfarenheter, hos fysioterapeuter till elitfotbollslag, rörande orsaker till skador samt viktiga komponenter för skadeförebyggande arbete inom elitfotboll. Metod: Studien har en kvalitativ ansats med deskriptiv design. Fem semistrukturerade intervjuer genomfördes och bearbetades genom en kvalitativ innehållsanalys. Resultat: Inom ”Orsaker till skador” identifierades fem kategorier; ”Fysisk belastning”, ”Psykisk- och social press”, ”Tränartyp”, ”Spelsituation” och ”Social situation”. ”Komponenter för skadeförebyggande arbete” genererade sex kategorier; ”Lagets resurser”, ”Planera belastning”, ”Kommunikation mellan medicinska teamet, tränarna och spelarna”, ”Utbildning av medicinska teamet, tränarna och spelarna”, ”Hitta balans i spelarnas vardag” och ”Hur spelarna mår fysiskt och psykiskt”. Konklusion: Flera aspekter påverkar uppkomsten av skador och därav behöver flera komponenter tas i beaktning vid förebyggandet av dessa. Vidare studier behövs för att täcka in ytterligare områden och för att kunna dra slutsatser om vilka av de möjliga komponenterna som bör prioriteras.Background: Soccer is the world´s biggest sport and is responsible for a lot of all the sports related injuries. These injuries can result in impaired health, expenses for the society and the end of a career. The main focus of today´s research regarding injury preventions are different types of training. There may also be other components that might reduce the risk of getting injured that hasn´t been explored as much.  Purpose: The aim was to investigate the perceptions and experiences of physiotherapists working for elite soccer clubs, regarding causes of injuries and important injury preventive methods. Method: A qualitative descriptive design was used in this study. Five semi structured interviews were performed and a qualitative content analysis was used. Result: Based on ”Causes of injuries”, five categories were identified; "Physical load", "Psychological and social pressure", "Type of trainer", "Game situation" and "Social situation". ”Injury prevention methods” generated six categories; "The team´s resources", "Planning Load", "Communication between the medical team, coaches and players", "Education of the medical team, coaches and players", "Finding balance in players' everyday life," and "How the players feel physically and psyochologically." Conclusion: Several aspects affect the occurrence of injuries, and therefore several components need to be taken into account in the prevention of these. Further studies are needed to cover additional areas and to draw conclusions about which of the possible components that should be prioritized

Fysioterapeuters syn på orsaker till skador samt hur dessa kan förebyggas, inom svensk elitfotboll - en intervjustudie

Bakgrund: Fotboll är en av världens största idrotter och står för en stor del av alla sportrelaterade skador. Skadorna kan leda till nedsatt hälsa, kostnader för samhället samt slutet av en spelarkarriär. Hittills har forskningen främst fokuserats på träning när det gäller skadeförebyggande åtgärder. Det finns även andra faktorer som kan minska skaderisken men som i dagsläget inte utforskats i samma utsträckning. Syfte: Syftet var att undersöka uppfattningar och erfarenheter, hos fysioterapeuter till elitfotbollslag, rörande orsaker till skador samt viktiga komponenter för skadeförebyggande arbete inom elitfotboll. Metod: Studien har en kvalitativ ansats med deskriptiv design. Fem semistrukturerade intervjuer genomfördes och bearbetades genom en kvalitativ innehållsanalys. Resultat: Inom ”Orsaker till skador” identifierades fem kategorier; ”Fysisk belastning”, ”Psykisk- och social press”, ”Tränartyp”, ”Spelsituation” och ”Social situation”. ”Komponenter för skadeförebyggande arbete” genererade sex kategorier; ”Lagets resurser”, ”Planera belastning”, ”Kommunikation mellan medicinska teamet, tränarna och spelarna”, ”Utbildning av medicinska teamet, tränarna och spelarna”, ”Hitta balans i spelarnas vardag” och ”Hur spelarna mår fysiskt och psykiskt”. Konklusion: Flera aspekter påverkar uppkomsten av skador och därav behöver flera komponenter tas i beaktning vid förebyggandet av dessa. Vidare studier behövs för att täcka in ytterligare områden och för att kunna dra slutsatser om vilka av de möjliga komponenterna som bör prioriteras.Background: Soccer is the world´s biggest sport and is responsible for a lot of all the sports related injuries. These injuries can result in impaired health, expenses for the society and the end of a career. The main focus of today´s research regarding injury preventions are different types of training. There may also be other components that might reduce the risk of getting injured that hasn´t been explored as much.  Purpose: The aim was to investigate the perceptions and experiences of physiotherapists working for elite soccer clubs, regarding causes of injuries and important injury preventive methods. Method: A qualitative descriptive design was used in this study. Five semi structured interviews were performed and a qualitative content analysis was used. Result: Based on ”Causes of injuries”, five categories were identified; "Physical load", "Psychological and social pressure", "Type of trainer", "Game situation" and "Social situation". ”Injury prevention methods” generated six categories; "The team´s resources", "Planning Load", "Communication between the medical team, coaches and players", "Education of the medical team, coaches and players", "Finding balance in players' everyday life," and "How the players feel physically and psyochologically." Conclusion: Several aspects affect the occurrence of injuries, and therefore several components need to be taken into account in the prevention of these. Further studies are needed to cover additional areas and to draw conclusions about which of the possible components that should be prioritized

Energy-Optimal Timing of Robot Stations Subject to Gaussian Disturbances

This paper proposes an optimization model for optimizing the energy use of industrial robots in production systems affected by stochastic disturbances. In the model there are a number of operations that needs to be completed by the robots before a deadline. The operations are of two types, one type that can not be controlled and have stochastic execution times. The other type are robot movements, and by extending their execution times energy can be saved. The goal of the optimization is to find the optimal combination of execution times for the robot movements, while meeting the deadline with a given probability

Online Energy-Optimal Timing of Stochastic Robot Stations

This paper investigates the problem of reducing the energy use of the movements of robots in industrial robot stations that have variations in execution times. An online method is presented that repeatedly solves an optimization problem during the execution of the station, that tries to minimize the energy use by finding the optimal execution times of the robot movements while at the same ensuring that the deadline of the station is met with a high enough probability. The method involves reformulating the original optimization problem, which is stochastic and nonlinear, into a convex version that can be solved efficiently. The method is tested on a simulated robot station and the result shows that the method is fast enough to be useable online and reduces the energy use of the station

Simulation based energy optimization of robot stations by motion parameter tuning

This paper presents energy optimization of a welding station from a manufacturing line in an automotive factory. The aim of the optimization is to find free time between operations, where it is possible to extend the execution time of the robot movements, and thereby saving energy, without extending the cycle time of the whole station. The station is modeled and optimized in a simulation platform. The optimization algorithm works by iteratively limiting the maximum velocity of the robot movements, until no more free time exists. Simulation results show that the energy use, peak power and jerk of the robots can be reduced significantly

Applied energy optimization of multi-robot systems through motion parameter tuning

In this paper, an optimization method for energy reduction of robot stations is presented, including an evaluation on an industrial robot station. The problem is formulated as a convex mixed integer nonlinear optimization problem, where the objective is to reduce the energy use by finding the optimal execution time and execution order of the robot motions. A simulation model of the station is used to find simplified energy models of the robot motions, that is used to solve the optimization problem. The optimal execution times of the robot motions are realized by tuning parameters in the robot control system. Different types of parameter settings are tested, such as reduced acceleration and velocity. The optimal parameter settings are then implemented in robot code in a real four robot welding station. The result shows a 12% reduction in energy use, without extending the cycle time of the station. A validation of the energy models used to solve the optimization problem is also made, by comparing them with real energy measurements

Fysioterapeuters syn på orsaker till skador samt hur dessa kan förebyggas, inom svensk elitfotboll - en intervjustudie

Bakgrund: Fotboll är en av världens största idrotter och står för en stor del av alla sportrelaterade skador. Skadorna kan leda till nedsatt hälsa, kostnader för samhället samt slutet av en spelarkarriär. Hittills har forskningen främst fokuserats på träning när det gäller skadeförebyggande åtgärder. Det finns även andra faktorer som kan minska skaderisken men som i dagsläget inte utforskats i samma utsträckning. Syfte: Syftet var att undersöka uppfattningar och erfarenheter, hos fysioterapeuter till elitfotbollslag, rörande orsaker till skador samt viktiga komponenter för skadeförebyggande arbete inom elitfotboll. Metod: Studien har en kvalitativ ansats med deskriptiv design. Fem semistrukturerade intervjuer genomfördes och bearbetades genom en kvalitativ innehållsanalys. Resultat: Inom ”Orsaker till skador” identifierades fem kategorier; ”Fysisk belastning”, ”Psykisk- och social press”, ”Tränartyp”, ”Spelsituation” och ”Social situation”. ”Komponenter för skadeförebyggande arbete” genererade sex kategorier; ”Lagets resurser”, ”Planera belastning”, ”Kommunikation mellan medicinska teamet, tränarna och spelarna”, ”Utbildning av medicinska teamet, tränarna och spelarna”, ”Hitta balans i spelarnas vardag” och ”Hur spelarna mår fysiskt och psykiskt”. Konklusion: Flera aspekter påverkar uppkomsten av skador och därav behöver flera komponenter tas i beaktning vid förebyggandet av dessa. Vidare studier behövs för att täcka in ytterligare områden och för att kunna dra slutsatser om vilka av de möjliga komponenterna som bör prioriteras.Background: Soccer is the world´s biggest sport and is responsible for a lot of all the sports related injuries. These injuries can result in impaired health, expenses for the society and the end of a career. The main focus of today´s research regarding injury preventions are different types of training. There may also be other components that might reduce the risk of getting injured that hasn´t been explored as much.  Purpose: The aim was to investigate the perceptions and experiences of physiotherapists working for elite soccer clubs, regarding causes of injuries and important injury preventive methods. Method: A qualitative descriptive design was used in this study. Five semi structured interviews were performed and a qualitative content analysis was used. Result: Based on ”Causes of injuries”, five categories were identified; "Physical load", "Psychological and social pressure", "Type of trainer", "Game situation" and "Social situation". ”Injury prevention methods” generated six categories; "The team´s resources", "Planning Load", "Communication between the medical team, coaches and players", "Education of the medical team, coaches and players", "Finding balance in players' everyday life," and "How the players feel physically and psyochologically." Conclusion: Several aspects affect the occurrence of injuries, and therefore several components need to be taken into account in the prevention of these. Further studies are needed to cover additional areas and to draw conclusions about which of the possible components that should be prioritized

Energy-Optimal Timing of Stochastic Robot Stations in Automotive Production Lines

This paper investigates the problem of reducing the energy use of robot stations with stochastic execution times in production lines in automotive factories. First, real stochastic cycle time data is used to analyze and improve the cycle time. The result shows that the cycle time mean can be decreased with the cost of an increase in cycle time variance. Second, the cycle time data is combined with energy models of real robot stations. A stochastic optimization problem is formulated where the goal is to reduce the energy use of the stations in the production line by lowering the robot velocities, while not affecting the cycle time of the production line. The optimization problem is solved and the resulting energy optimized station is simulated using the improved cycle time. The result shows that up to 23 percent of the energy use can be reduced by only marginally affecting the cycle time variance of the production line