8 research outputs found
Optimal design of a 2-DOF pick-and-place parallel robot using dynamic performance indices and angular constraints
This paper presents an approach for the optimal design of a 2-DOF translational pick-and-place parallel robot. By taking account of the normalized inertial and centrifugal/Coriolis torques of a single actuated joint, two global dynamic performance indices are proposed for minimization. The pressure angles within a limb and between two limbs are considered as the kinematic constraints to prevent direct and indirect singularities. These considerations together form a multi-objective optimization problem that can then be solved by the modified goal attainment method. A numerical example is discussed. A number of robots designed by this approach have been integrated into production lines for carton packing in the pharmaceutical industry
Optimal design of a 2-DOF pick-and-place parallel robot using dynamic performance indices and angular constraints
This paper presents an approach for the optimal design of a 2-DOF translational pick-and-place parallel robot. By taking account of the normalized inertial and centrifugal/Coriolis torques of a single actuated joint, two global dynamic performance indices are proposed for minimization. The pressure angles within a limb and between two limbs are considered as the kinematic constraints to prevent direct and indirect singularities. These considerations together form a multi-objective optimization problem that can then be solved by the modified goal attainment method. A numerical example is discussed. A number of robots designed by this approach have been integrated into production lines for carton packing in the pharmaceutical industry
Optimal kinematic design of 2-DOF parallel manipulators with well-shaped workspace bounded by a specified conditioning index
This paper presents a hybrid method for the optimum kinematic design of two-degree-of-freedom (2-DOF) parallel manipulators with mirror symmetrical geometry. By taking advantage of both local and global approaches, the proposed method can be implemented in two steps. In the first step, the optimal architecture, in terms of isotropy and the behavior of the direct Jacobian matrix, is achieved, resulting in a set of closed-form parametric relationships that enable the number of design variables to be reduced. In the second step, the workspace bounded by the specified conditioning index is generated, which allows only one design parameter to be determined by optimizing a comprehensive index in a rectangular workspace. The kinematic optimization of a revolute-jointed 2-DOF parallel robot has been taken as an example to illustrate the effectiveness of this approach
Simulation and Optimisation of a Two Degree of Freedom, Planar, Parallel Manipulator
Development in pick-and-place robotic manipulators continues to grow as factory processes are
streamlined. One configuration of these manipulators is the two degree of freedom, planar, parallel
manipulator (2DOFPPM). A machine building company, RML Engineering Ltd., wishes to develop custom
robotic manipulators that are optimised for individual pick-and-place applications. This thesis develops
several tools to assist in the design process.
The 2DOFPPM’s structure lends itself to fast and accurate translations in a single plane. However, the
performance of the 2DOFPPM is highly dependent on its dimensions. The kinematics of the 2DOFPPM
are explored and used to examine the reachable workspace of the manipulator. This method of analysis
also gives insight into the relative speed and accuracy of the manipulator’s end-effector in the
workspace.
A simulation model of the 2DOFPPM has been developed in Matlab’s® SimMechanics®. This allows the
detailed analysis of the manipulator’s dynamics. In order to provide meaningful input into the simulation
model, a cubic spline trajectory planner is created. The algorithm uses an iterative approach of
minimising the time between knots along the path, while ensuring the kinematic and dynamic limits of
the motors and end-effector are abided by. The resulting trajectory can be considered near-minimum in
terms of its cycle-time.
The dimensions of the 2DOFPPM have a large effect on the performance of the manipulator. Four major
dimensions are analysed to see the effect each has on the cycle-time over a standardised path. The
dimensions are the proximal and distal arms, spacing of the motors and the height of the manipulator
above the workspace. The solution space of all feasible combinations of these dimensions is produced
revealing cycle-times with a large degree of variation over the same path.
Several optimisation algorithms are applied to finding the manipulator configuration with the fastest
cycle-time. A random restart hill-climber, stochastic hill-climber, simulated annealing and a genetic
algorithm are developed. After each algorithm’s parameters are tuned, the genetic algorithm is shown
to outperform the other techniques
Simulation and Optimisation of a Two Degree of Freedom, Planar, Parallel Manipulator
Development in pick-and-place robotic manipulators continues to grow as factory processes are
streamlined. One configuration of these manipulators is the two degree of freedom, planar, parallel
manipulator (2DOFPPM). A machine building company, RML Engineering Ltd., wishes to develop custom
robotic manipulators that are optimised for individual pick-and-place applications. This thesis develops
several tools to assist in the design process.
The 2DOFPPM’s structure lends itself to fast and accurate translations in a single plane. However, the
performance of the 2DOFPPM is highly dependent on its dimensions. The kinematics of the 2DOFPPM
are explored and used to examine the reachable workspace of the manipulator. This method of analysis
also gives insight into the relative speed and accuracy of the manipulator’s end-effector in the
workspace.
A simulation model of the 2DOFPPM has been developed in Matlab’s® SimMechanics®. This allows the
detailed analysis of the manipulator’s dynamics. In order to provide meaningful input into the simulation
model, a cubic spline trajectory planner is created. The algorithm uses an iterative approach of
minimising the time between knots along the path, while ensuring the kinematic and dynamic limits of
the motors and end-effector are abided by. The resulting trajectory can be considered near-minimum in
terms of its cycle-time.
The dimensions of the 2DOFPPM have a large effect on the performance of the manipulator. Four major
dimensions are analysed to see the effect each has on the cycle-time over a standardised path. The
dimensions are the proximal and distal arms, spacing of the motors and the height of the manipulator
above the workspace. The solution space of all feasible combinations of these dimensions is produced
revealing cycle-times with a large degree of variation over the same path.
Several optimisation algorithms are applied to finding the manipulator configuration with the fastest
cycle-time. A random restart hill-climber, stochastic hill-climber, simulated annealing and a genetic
algorithm are developed. After each algorithm’s parameters are tuned, the genetic algorithm is shown
to outperform the other techniques
A Flexible, Low-Power, Programmable Unsupervised Neural Network Based on Microcontrollers for Medical Applications
We present an implementation and laboratory tests of a winner takes all (WTA) artificial neural network (NN) on two microcontrollers (ÎĽC) with the ARM Cortex M3 and the AVR cores. The prospective application of this device is in wireless body sensor network (WBSN) in an on-line analysis of electrocardiograph (ECG) and electromyograph (EMG) biomedical signals. The proposed device will be used as a base station in the WBSN, acquiring and analysing the signals from the sensors placed on the human body. The proposed system is equiped with an analog-todigital converter (ADC), and allows for multi-channel acquisition of analog signals, preprocessing (filtering) and further analysis