Closed-loop Motion Control Research Articles

SU-FF-J-03: A Dynamic Phantom for 4-Dimensional Imaging and Radiation Therapy Verification

Purpose: Current research is producing a variety of methods to model breathing motion in the abdomen and thoracic regions. Testing of these methods is hampered by the lack of a reproducible standard that reproduces complex, multidimensional motion. The purpose of this study was to create a 4D phantom that could be used for evaluation of breathing motion. Method and Materials: A 4-dimensional (4D) stage capable of arbitrary multidimensional motion with speeds up to 10 cm/sec was constructed. The positioning system was developed using stepping motor-actuated linear slides (Velmex Inc.) capable of carrying a 10 kg water-equivalent phantom. A 4 axis motor controller (National Instruments) with onboard PID algorithms was used with an amplifier capable of 4 Amps per axis at 1.7 V (Primatics, Inc). Custom software was written to allow input trajectories as a text file of x, y, and z coordinates spaced 20 ms apart. A 3 Dimensional digitizing arm (Immersion Corporation) was physically connected to the system to monitor stage localization accuracy. The intended position and measured positions were compared over a series of points. Results: The scanning system produced highly verifiable and reproducible trajectories for a variety of ellipses and modeled tumor trajectories. The system also produced very accurate and precise positioning using simple raster scanning patterns. The average error was 0.1397mm, where the published error for the digitizing arm is 0.3mm. The total cost to construct the phantom was less than $10,000. Conclusion: The 4D phantom produces accurate positioning throughout the range of motion found in human tumors. It can provide a ‘gold standard’ for evaluating 4D CT, organ motion, and internal localization systems for both research and clinical applications. Further refinements, such as the addition of encoders for truly closed loop motion control, are ongoing.

1012 ステッピングモータ駆動マニピュレータの閉ループ運動制御(2) : Peg-in-hole実験(ロボティクス・メカトロニクスIII)

1012 ステッピングモータ駆動マニピュレータの閉ループ運動制御(2) : Peg-in-hole実験(ロボティクス・メカトロニクスIII)

1011 ステッピングモータ駆動マニピュレータの閉ループ運動制御(1) : 軌道制御実験(ロボティクス・メカトロニクスIII)

1011 ステッピングモータ駆動マニピュレータの閉ループ運動制御(1) : 軌道制御実験(ロボティクス・メカトロニクスIII)

Motor driving leg design for bionic crab-like robot

The paper presents the design of walking leg for bionics crab-like robot, which is driven with micro servo motor. The kinematic characteristics of the bionics machine are analysed for optimized structure parameters, which has been used in the robot design. A three closed loop motor control system structure for joint driver is also given, as well as the multi-joint driving system for walking robot leg.

Closed- and open-loop handwriting performance in patients with multiple sclerosis.

Normal subjects use an open-loop motor control strategy in handwriting, but they are able to switch to closed-loop motor control when the demands on accuracy increase. These closed-loop handwriting movements of normal subjects resemble the inefficient movements found in writing-impaired patients. The hypothesis that such movement deficits may in fact reflect the use of a closed-loop strategy was tested in a group of writing-impaired patients with multiple sclerosis (MS). The handwriting movements of 10 MS patients and 20 control subjects were examined with a digitizing tablet. Three conditions were used: a standard writing task (expt 1), a closed-loop condition (expt 2), and an open-loop condition (expt 3). Individual stroke movements were analysed. Stroke duration and segmentation were increased for MS patients in the standard writing task. The same was found for control subjects when they wrote under closed-loop conditions. However, under open-loop conditions, the handwriting movements of the MS patients were as fast and fluent as that of control subjects. The results support the hypothesis that the movement characteristics of the writing-impaired MS patients reflect an inadequate use of a closed-loop motor control strategy.

Taking Sensors Out of Motors

This article discusses that advanced signal processors are replacing the feedback sensors that had been required for motor control in applications ranging from disk drives to appliance motors. The traditional method of closed-loop motor control has been to use one or more sensors to provide feedback. A growing number of applications, however, are now eliminating the sensor through one of several methods, such as back electromotive force (EMF) or inductance measurement. Sensorless motors are best suited for applications where speed control is needed, but precise position control is not critical. Sensorless motors are proving to be most appropriate for applications where the position of the rotor does not have to be pinpointed with great accuracy and all that is needed is speed and torque control. Prime candidates for sensorless motors are applications where open-loop scalar control had been used but better speed regulation and more torque at low speed are needed.

Neural network implementation for real-time closed-loop motion control of redundant robots : Qin Chen, J.Y.S. Luh, pp 123–128

Neural network implementation for real-time closed-loop motion control of redundant robots : Qin Chen, J.Y.S. Luh, pp 123–128

Neural Network Implementation for Realrtime Closed-Loop Motion Control of Redundant Robots

Abstract This paper describes an implementation of closed-loop motion control of redundant robots using a multi-layer neural network. The control scheme is developed based on the well known Hamilton-Jacobi-Bellman algorithm of optimal control. The algorithm requires solving the algebraic matrix Riccati equation, which is very computationally time consuming, and not practical for real time control applications. This paper illustrates that the computing time can be drastically reduced by replacing solving the Riccati equation with a neural network. The effectiveness of the neural controller is demonstrated by applying it to a PUMA 650 robot with a simulated prismatic joint inserted between the elbow and the wrist to obtain an extra degree of freedom.

TMS320 design for vector and current control of AC motor drives

A new dual digital signal processor board is described for the control of permanent magnet synchronous motors (PMSMs). The circuit has been tested using a 1.5 kW PMSM and characterised over motor speed ranges up to 3000 rpm. The use of single chip microcontrollers has proven to be a compact, high performance solution for AC motor closed loop control

A microcontroller for closed-loop motion control

The Spherosyn displacement transducer's robustness offers many advantages in closed-loop digital motion or position control systems. The microprocessor interface is fundamental to the operation and performance under the arduous conditions typical of automated industrial machinery. Through comparisons of a number of differing circuit techniques, a reliable minimal microcontroller design is presented. Optimization through modelling and the results of experimentation are supported by a novel interface arrangement. The final configuration provides a basis for a number of performance enhanced systems.

Blanche-an experiment in guidance and navigation of an autonomous robot vehicle

The principal components and capabilities of Blanche, an autonomous robot vehicle, are described. Blanche is designed for use in structured office or factory environments rather than unstructured natural environments, and it is assumed that an offline path planner provides the vehicle with a series of collision-free maneuvers, consisting of line and arc segments, to move the vehicle to a desired position. These segments are sent to a low-level trajectory generator and closed-loop motion control. The controller assumes accurate knowledge of the vehicle's position. Blanche's position estimation system consists of a priori map of its environment and a robust matching algorithm. The matching algorithm also estimates the precision of the corresponding match/correction that is then optimally (in a maximum-likelihood sense) combined with the current odometric position to provide an improved estimate of the vehicle's position. The system does not use passive or active beacons. Experimental results are reported. >