Real-time force optimization in parallel kinematic chains under inequality constraints

1992 ◽  
Vol 8 (4) ◽  
pp. 439-450 ◽  
Author(s):  
M.A. Nahon ◽  
J. Angeles
Keyword(s):  
Real Time ◽  
Inequality Constraints ◽  
Kinematic Chains ◽  
Force Optimization ◽  
Parallel Kinematic

Drive System Sizing of a 6-DOF Parallel Robotic Platform

2014 ◽  
Author(s):  
Hermes Giberti ◽  
Davide Ferrari
Keyword(s):  
Optimal Solution ◽  
Parallel Robot ◽  
Drive System ◽  
Pareto Optimal ◽  
Hardware In The Loop ◽  
Motion Simulation ◽  
Inverse Dynamic ◽  
Kinematic Chains ◽  
Fixed Base ◽  
Parallel Kinematic

In this work, it is considered a 6-DoF robotic device intended to be applied for hardware-in-the-loop (HIL) motion simulation with wind tunnel models. The requirements have led to a 6-PUS parallel robot whose linkages consist of six closed-loop kinematic chains, connecting the fixed base to the mobile platform with the same sequence of joints: actuated Prism (P), Universal (U), and Spherical (S). As is common for parallel kinematic manipulators (PKMs), the actual performances of the robot depend greatly on its dimensions. Therefore, a kinematic synthesis has been performed and several Pareto-optimal solutions have been obtained through a multi-objective optimization of the machine geometric parameters, using a genetic algorithm. In this paper, the inverse dynamic analysis of the robot is presented. Then, the results are used for the mechanical sizing of the drive system, comparing belt- to screw-driven units and selecting the motor-reducer groups. Finally, the best compromise Pareto-optimal solution is definitely chosen.

Real-Time Optimal Coherent Phantom Track Generation via the Virtual Motion Camouflage Approach

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Yunjun Xu ◽  
Gareth Basset
Keyword(s):  
Real Time ◽  
Computational Cost ◽  
Inequality Constraints ◽  
Early Termination ◽  
Planning Problem ◽  
Motion Camouflage ◽  
Equality And Inequality Constraints ◽  
Time Optimal ◽  
And Control ◽  
Air Vehicles

Coherent phantom track generation through controlling a group of electronic combat air vehicles is currently an area of great interest to the defense agency for the purpose of deceiving a radar network. However, generating an optimal or even feasible coherent phantom trajectory in real-time is challenging due to the high dimensionality of the problem and severe geometric, as well as state, control, and control rate constraints. In this paper, the bio-inspired virtual motion camouflage based methodology, augmented with the derived early termination condition, is investigated to solve this constrained collaborative trajectory planning problem in two approaches: centralized (one optimization loop) and decentralized (two optimization loops). Specifically, in the decentralized approach, the first loop finds feasible phantom tracks based on the early termination condition and the equality and inequality constraints of the phantom track. The second loop uses the virtual motion camouflage method to solve for the optimal electronic combat air vehicle trajectories based on the feasible phantom tracks obtained in the first loop. Necessary conditions are proposed for both approaches so that the initial and final velocities of the phantom and electronic combat air vehicles are coherent. It is shown that the decentralized approach can solve the problem much faster than the centralized one, and when the decentralized approach is applied, the computational cost remains roughly the same for the cases when the number of nodes and/or the number of electronic combat air vehicles increases. It is concluded that the virtual motion camouflage based decentralized approach has promising potential for usage in real-time implementation.

Control of Force Distribution in Robotic Mechanisms Containing Closed Kinematic Chains

1981 ◽  
Vol 103 (2) ◽  
pp. 134-141 ◽  
Author(s):  
D. E. Orin ◽  
S. Y. Oh
Keyword(s):  
Linear Programming ◽  
Basic Problem ◽  
Inequality Constraints ◽  
Force Distribution ◽  
Joint Torques ◽  
Kinematic Chains ◽  
System Trajectory ◽  
Reaction Forces ◽  
Tripod Gait ◽  
Weighted Combination

Control of the force distribution in locomotion and manipulation systems containing closed kinematic chains is an important problem since many tasks such as walking or grasping depend upon it. The basic problem is to solve for the input joint torques for a particular system trajectory and is usually underspecified. As such, linear programming has been used to obtain a solution which optimizes a weighted combination of energy consumption and load balancings. Inequality constraints on the maximum actuator torques and reaction forces at the tip of each chain of the system are imposed, in addition to equality constraints which specify movement in a desired system trajectory. An example is given in which the joint torques to drive a hexapod locomotion vehicle in a tripod gait are computed.

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