Bone tissue remodels throughout life in response to mechanical loads. Impaired activities of bone cells (osteocytes, osteoblasts and osteoclasts) result in a disruption of the bone remodelling cycle, ...which eventually leads to bone disorders such as osteoporosis. To develop efficient therapeutic strategies against bone disorders, new tools are needed to unravel the bone remodelling cycle at the molecular level. Here, we developed a microfluidic platform, which should allow understanding the bone remodelling cycle in much more detail and ultimately be used to discover new therapeutic compounds. We focused specifically on studying cell-cell communication between osteocytes and osteoblasts cells via connexin 43-gap junctions. Therefore, a new cell printing method was developed to create living cellular bone cell arrays in a microfluidic channel. Several cell printing designs where osteocytes and osteoblasts heterotypically interacted at localized interfaces were evaluated. Physical contacts between the bone cells were characterized at high resolution by correlative atomic force microscopy (AFM)-fluorescence microscopy. We demonstrated that the platform is compatible with single-cell mechanostimulation by AFM nanoindentation and subsequent fluorescent analysis of the mechanoresponse. As a proof of concept, we showed the functionality of the platform by analysing the induced
-like Ca
wave in the printed osteocyte-osteoblast network upon mechanical stimulation by fluid flow shear stress.
In this paper, we propose an improved discrete bacterial foraging algorithm to determine the optimal sequence of parts and robot moves in order to minimize the cycle time for the 2-machine robotic ...cell scheduling problem with sequence-dependent setup times. We present a method to convert the solutions from continuous to discrete form. In addition, two neighborhood search techniques are employed to updating the positions of each bacterium during chemotaxis and elimination–dispersal operations in order to accelerate the search procedure and to improve the solution. Moreover, a multi-objective optimization algorithm based on NSGA-II combined with the response surface methodology and the desirability technique is applied to tune the parameters as well as to enhance the convergence speed of the proposed algorithm. Finally, a design of experiment based on central composite design is used to determine the optimal settings of the operating parameters of the proposed algorithm. The results of the computational experimentation with a large number of randomly generated test problems demonstrate that the proposed method is relatively more effective and efficient than the state-of-the-art algorithms in minimizing the cycle time in the robotic cell scheduling.
Robots are used in manufacturing cells for wide purposes including pick and place of the items from a location to a destination. As far as the authors’ knowledge in this context, the scheduling ...problem of a real-life flexible robotic cell (FRC) with intermediate buffers is missing in the literature. Therefore, in this study, the process-sequencing problem of a real-life FRC is considered, aiming to minimize the cyclic operation time of the cell. The problem is mathematically modeled and solved for a real case. Since computation times for solving the problems rise exponentially with increasing the number of machines in the FRC, a genetic, a simulated annealing, and a hybrid genetic algorithms are proposed to solve the large-sized problems. The objective function value of a given solution in metaheuristic algorithms is computed by solving a linear programming model. After tuning the parameters of the proposed algorithms, several numerical instances are solved, and the performance of these algorithms are evaluated and compared. The results show that the performance of the hybrid genetic algorithm was significantly better than both genetic and simulated annealing algorithms.
Biological cell injection is laborious work that requires lengthy training and suffers from a low success rate. In this paper, a robotic cell-injection system for automatic injection of ...batch-suspended cells is proposed. To facilitate the process, these suspended cells are held and fixed to a cell array by a specially designed cell-holding device, and injected one by one through an ldquoout-of-planerdquo cell-injection process. A micropipette equipped with a polyvinylidene fluoride microforce sensor to measure real-time injection force is integrated in the proposed system. Through calibration, an empirical relationship between the cell-injection force and the desired injector pipette trajectory is obtained in advance. Then, after decoupling the out-of-plane cell injection into a position control in the X - Y horizontal plane and an impedance control in the Z -axis, a position and force control algorithm is developed to control the injection pipette. The depth motion of the injector pipette, which cannot be observed by microscope, is indirectly controlled via the impedance control, and the desired force is determined from the online X - Y position control and cell calibration results. Finally, experimental results demonstrate the effectiveness of the proposed approach.
We consider a robotic cell served by a dual-gripper robot that consists of identical CNC machines placed linearly and a material handling robot loading/unloading the machines and transporting the ...parts between them. Identical parts are to be processed in this system and the CNC machines are capable of performing all the operations that a part requires. We consider the problem of sequencing activities of the robot in order to maximize the throughput rate. As a consequence of the flexibility of the CNC machines, a new class of robot move sequences, named as pure cycles, arises. In a pure cycle, the robot loads and unloads each machine once and each part is processed on exactly one of the machines. Thereby, the problem is to determine the best pure cycle that maximizes the throughput rate. We first determine the feasibility conditions for the pure cycles and prove some basic results that reduces the number of feasible pure cycles to be investigated. We analyze 2-machine robotic cells in detail and prove that five of the cycles among a huge number of feasible pure cycles dominate the rest. We determine the parameter regions in which each of the five cycles is optimal. We also analyze the performance improvement that can be attained by using a dual gripper robot and provide managerial insights.
•This is the first study to analyze pure robot move cycles in a dual gripper robotic cell.•Proposed a new lower bound for the general case.•For two-machine instances, we identified optimal pure cycles corresponding to all possible parameter values.•Conducted an economic analysis for justifying investment decisions on dual gripper robots.
•Multiple parts multi-unit robotic cell scheduling problem is considered.•Mathematical programming formulation and parallel hybrid metaheuristics are developed.•Heuristic algorithm provides ...near-optimal solutions in reasonable CPU time.•Utilizing multi-unit cycles can increase the throughput by 20%.
We consider a flow shop type manufacturing cell consisting of m machines and a material handling robot producing multiple parts. The robot transfers the parts between the machines and loads/unloads the machines. We consider the cyclic scheduling of the parts and the robot moves with the objective of maximizing the throughput rate. We develop a mixed integer linear programming formulation of the problem. The formulation is improved with several valid inequalities and reformulations of the constraints. We also develop a hybrid metaheuristic algorithm for this strongly NP-Hard problem. The algorithm is modified to handle both 1-unit and multi-unit robot cycles. Multi-threading is used to parallelize the algorithm in order to improve its efficiency. After calibrating the parameters of the heuristic algorithm, an extensive computational study is performed to evaluate its performance. The results of this study revealed that the developed heuristic provides near-optimal solutions in reasonable solution times. The effects of parallelization and the benefits of considering multi-unit cycles instead of 1-unit cycles are also quantified. Our computational tests show that multi-unit cycles improve the throughput rate by 9% on the average. The improvement can reach to 20% depending on the problem parameters.
Increasing the Efficiency of a Robotic Cell Using Simulation Juhás, Martin; Juhásová, Bohuslava; Nemlaha, Eduard ...
Vedecké práce Materiálovotechnologickej fakulty Slovenskej technickej univerzity v Bratislave so sídlom v Trnave,
09/2021, Letnik:
29, Številka:
49
Journal Article
Recenzirano
Odprti dostop
The paper deals with the possibilities of increasing the efficiency of a robotic cell. The robot assembly station is a part of a multi-robotic workplace capable of performing solitary operations. The ...complete production cycle of the cell is subjected to a thorough analysis. Deficiencies, having a direct impact on cell efficiency, are identified. These shortcomings include redundant movements of the robotic arm, the absence of an inspection mechanism for the presence of assembly parts, and inefficient instructions of the production cycle algorithm. The identified deficiencies are eliminated using the CIROS simulation tool. The result of the adjustments is a global 11.4% increase in the efficiency of the robotic cell in terms of time performance.
This study focuses on the domain of a two-machine robotic cell scheduling problem under three inspection scenarios. We propose the first analytical method for minimizing the partial cycle time of ...cells with in-process and post-process inspection scenarios, and then we convert this cell into a multi-function robotic cell with in-line inspection scenario. For the first scenario, parts are inspected in one of the production machines using multiple sensors, while the inspection process is performed by an independent inspection machine for the second scenario. Alternatively, the inspection can be performed by a multi-function robot for the third scenario. A distinguishing characteristic of this robot is that it can perform inspection of the part in transit. However, the robot cannot complete the part transition and load it on the next destination machine if it identifies a fault in the part. The stochastic nature of the process prevents us from applying existing deterministic solution methods for corresponding scheduling problems. In the first stage, we present a heuristic method that converts a multiple-sensor inspection system into a single-sensor inspection system. The expected cycle times of two different cycles are derived based on a geometric distribution, and then the maximum expected throughput is pursued for in-process and post-process inspection sensors, respectively. In the second stage, we develop the inspection system into an in-line inspection system using a multi-function robot. Finally, we determine if it is technically feasible and profitable to replace the in-process (or post-process) inspection scenario with the in-line inspection scenario.
•We study the scheduling of a two-machine robotic cell with an inspection process.•All partial cycle times are derived under three different inspection scenarios.•The maximum expected throughput is pursued for each inspection scenario.•A multiple-sensor inspection is converted into a single-sensor inspection.•We determine which inspection scenario has the highest performance.
This paper deals with the multi-degree cyclic robotic flow shop cell scheduling problem with multiple robots. All the parts are processed successively through the machines with standard processing ...times while single gripper robots perform the transportation operations of parts between the machines. Due to the special characteristics of the considered problem, a metaheuristic algorithm based on ant colony optimization has been proposed. The proposed algorithm simultaneously determines the optimal degree of the cyclic schedule, the robot assignments for the transportation operations, and the optimal sequence of robots' moves, which in return maximize the throughput rate. The efficiency of the proposed metaheuristic algorithm is examined by a computational study on a set of randomly generated problem instances.
•This research studies the k-degree cyclic robotic flow shop cell scheduling problem.•Multiple single gripper robots are considered to perform transportation operations.•An ACO based algorithm is proposed to minimize the cycle time for per produced part.•The characteristics of the considered problem are stated by an instance problem.•The proposed algorithm finds the appropriate cycle degree of the considered problem.
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