Showing 9 results for Trajectory Planning
Mahmood Karimi, , ,
Volume 10, Issue 4 (12-2010)
Abstract
Abstract - In this paper, an optimal trajectory planning method is presented for robot manipulators with multiple degrees of freedom in 3D space using a new analytical technique for collision avoidance in the presence of ellipsoidal obstacles. To generate the robot’s trajectory, a genetic algorithm with a fuzzy mutation rate is introduced to have a quick access to optimal solutions in a complex workspace. A cubic spline interpolation polynomial is applied to approximate trajectories in the joint space. In order to optimize the objective function, the genetic algorithm determines a number of interior points for curve fitting using interpolation polynomials. The performance of the proposed technique is demonstrated by simulations.
Volume 12, Issue 3 (12-2012)
Abstract
This paper presents a parameterization method to optimal trajectory planning and dynamic obstacle avoidance for Omni-directional robots. The aim of trajectory planning is minimizing a quadratic cost function while a maximum limitation on velocity and acceleration of robot is considered. First, we parameterize the trajectory using polynomial functions with unknown coefficients which transforms trajectory planning to an optimization problem. Then we use a novel method to solving the optimization problem and obtaining the unknown parameters. Finally, the efficiency of proposed approach is confirmed by simulation.
Maral Salehi, Amin Nikoobin,
Volume 13, Issue 14 (3-2014)
Abstract
In this paper, optimal trajectory planning of flexible joint manipulator in point-to-point motion is presented in which besides the determining the maximum load carrying capacity, the vibration amplitude is also reduced. The solution method is on the base of the indirect solution of optimal control problem. For this purpose, an appropriate objective function is defined, dynamic equations are derived in state space form, Hamiltonian function is developed and necessary optimality conditions are obtained by using the Pontryagin maximum principle. In order to reduce the vibration of the end effector during the path, an appropriate state variables are defined and the control law is improved to omit the suddenly variation in applied torque. Then, in order to illustrate the power and efficiency of the proposed method, a number of simulation tests are performed for a two-link manipulator. To this end, after deriving the equation in details, two simulations are performed. In the first case, determining the maximum load without considering the vibration is solved, in the second simulation, optimal trajectory with maximum load and minimum vibration is obtained. Finally discussions on the obtained results are presented.
Ali Reza Alemi Naeeni, Jafar Roshanian,
Volume 14, Issue 6 (9-2014)
Abstract
در این مقاله، طراحی مسیر بازگشت به جو یک کپسول فضایی از لحظه خروج از مدار اولیه تا رسیدن به شرایط عملکرد سیستم بازیابی مورد بررسی قرار می گیرد. برای این منظور دو روش حل عددی مسائل کنترل بهینه با رویکرد چند بازه ای توسعه داده شده و مورد استفاده و مقایسه قرار گرفته است. روش اول در دسته روشهای پرتاب (شوتینگ متد) قرار دارد که بهینه سازی در آن با استفاده از الگوریتم ژنتیک صورت می پذیرد. در این روش با بهره گیری از مدل جامعی برای توصیف تاریخچه کنترلی، به طور همزمان تعداد و چینش بازه ها و نوع تاریخچه کنترلی در هر بازه بهینه می شود. روش دوم موسوم به روش شبه طیفی می باشد که در آن متغیرهای حالت و کنترل برای ارضای همزمان قیود و شرایط بهینگی در نقاطی موسوم به گره ها تعیین می شوند. این روش هم با رویکرد چند بازه ای حل شده و با روش اول مقایسه گشته است. روشهای توسعه داده شده که در انتها عملکرد آنها مورد مقایسه و تحلیل قرار گرفته، قابل استفاده برای حل کلیه مسائل کنترل بهینه و طراحی مسیر می باشند.
Amin Nikoobin, Amir Kamal,
Volume 16, Issue 3 (5-2016)
Abstract
Time optimal trajectory planning of closed chain mechanisms has not been done by indirect method yet. In this paper, this problem is considered for a four bar mechanism and its solution is presented on the base of the indirect solution of optimal control problem. To this end, the additional coordinates are omitted using the holonomic constraints, so the dynamic equation is obtained with respect to only one generalized coordinate. Then the necessary conditions for optimality are derived using Pontryagin's minimum principle by considering the constraint on the applied torque. The obtained equations lead to a two-point boundary value problem (BVP) that its solution is the optimum answer. Unlike the direct methods that result in approximate solution, indirect method leads to an exact solution. But the main challenge in indirect method is solving the BVP. Solving this problem is sensitive to the initial guess. This problem is much more severe for time optimal problem which has a high nonlinear answer in bang-bang form. To overcome this problem an algorithm is proposed to solve the time optimal problem with any desired accuracy, and the initial solution can simply be zero at the start of the algorithm. But in the time optimal trajectory the large jerk is occurred, due to control signals switching. In order to overcome this problem, another algorithm is presented to calculate the minimum time with bounded jerk. Finally, the simulation results show the performance of the proposed method in time optimal trajectory planning.
Seyed Iman Kassaei, Amirreza Kosari,
Volume 17, Issue 12 (2-2018)
Abstract
In the present paper the problem of designing a flying vehicle trajectory to avoid the collision with Terrain by limiting the flight range in a flight corridor influenced by the shape of the terrain has been investigated. In order to improve the traceability of the designed trajectory, considering the performance characteristics of the aircraft, the effect of two performance parameters including of the maximum rate of climb and the maximum increasing rate of the flight path angle, are considered in the solution algorithm. In this regard, the quantification of the system performance, has been implemented during the definition of different cost functions to minimize the operating time, control effort and vertical acceleration imposing on the aircraft. Mathematical modeling of the terrain which is considered as the route location of the threat, has been implemented using a power polynomial solution for smoothing. Finally, optimal control theory and nonlinear programming approach are utilized to solve the defined problem. The evaluation of case studies and numerical simulations confirmed the effectiveness of the proposed approach to solve the planning problem in flying maneuvers with low altitude requirements for follow and avoidance of direct and indirect environmental hazards.
Hadi Sazgar, Shahram Azadi, Reza Kazemi,
Volume 18, Issue 2 (4-2018)
Abstract
The purpose of this research is to develop an advanced driver assistance system (ADAS) for the integrated longitudinal and lateral guidance of vehicles in high speed lane change maneuver. At the first step, the ADAS by considering the target vehicle position, the speed limit of the road and the available range of longitudinal acceleration produced several trajectories with different acceleration. Then, by considering vehicle and tire dynamics, the optimal trajectory is selected. Therefore, the chosen trajectory is collision free and feasible. Because the trajectory planning is carried out algebraically, its computational cost is low. This feature is very valuable in the experimental implementation. In the next step, using a combined longitudinal-lateral controller, the control inputs are calculated and transmitted to the brake/gas and steering actuators. The integrated controller design is based on sliding mode technique. Trajectory planning and controller design is based on a nonlinear tire model. Simulation results are presented and the results show the effectiveness of the integrated longitudinal and lateral guidance system.
A. Kosari, S.i. Kassaei , A. Rostampour , S. Seyedzamani,
Volume 20, Issue 5 (5-2020)
Abstract
In this paper, a novel method for designing the flight paths of an aircraft is presented based on the concept of conformal mapping. Here, a low-altitude route-planning problem has been considered. In this problem, maintaining the control effort to reduce aircraft's altitude and increasing the speed with the limitations of Terrain Following (TF) and Terrain Avoidance (TA) issues, is the main strategy of this performance maneuver. In the proposed approach, attempts are made to convert the real space including terrains and obstacles, in which their data are provided using a digital elevation map, into a pseudo obstacle-free virtual space with no barriers and altitude constraints. In this regard, the concept of conformal mapping has been used as a facilitating mathematical tool for this problem-solving space transformation. The transformation of the problem-solving spaces under the mapping leads to solving the problem of dynamic reflection, the performance criterion, and the real altitude constraints in the virtual space. It is noteworthy that in designing a path in a newly converted space, the effect of barriers on the formation of flight routes is somehow included in the equations expressed in the virtual space. The results of multiple case studies and numerical optimizations performed for 2D geometrical terrains and obstacles show that the proposed approach is more consistent with the basic flight concepts as well as real-world applications.
Volume 23, Issue 1 (1-2021)
Abstract
The side branches in tomato plants have a great impact on tomato yield and fruit quality and the pruning work is now basically done manually, which has high labor intensity and high-risk factor. The elevated cultivation of tomatoes was taken as the objective of this research and 6 degrees of freedom P-R-R-R-R-R tomato side branch pruning robotic arm was proposed. The dynamic simulation of the robotic arm in the obstacle environment was completed by ADAMS. Simulation results showed the angular velocity and angular acceleration curves of each joint. A trajectory planning method combining Cartesian space and joint space was proposed to ensure that the robotic arm can avoid obstacles while effectively reducing the impact during operation.
