Michal Tordon - Academia.edu (original) (raw)

Papers by Michal Tordon

This paper presents the implementation of an external axis control system on a conventional CNC m... more This paper presents the implementation of an external axis control system on a conventional CNC machine so that the machine can be actively controlled in response to sensors such as vision and force. The controller that runs on an external computer has direct access to the CNC controller for machine position sensing. The control signals to the machine are sent through purpose built circuitry via the machine's manual pulse generator (MPG) inputs. To demonstrate the accuracy and performance of the control system, it was used to visually track the profile of a mandrel used for shear spinning. The implemented system eliminates the parallax error and the need to use an accurate pixel resolution. The raw tracking data is processed by a curvature detection algorithm that detects linear and circular segments and segment transitions. The results show that the visual tracking system provides accurate tracking results that are well within the tolerances used in the industry.

This paper presents the implementation of an exter-nal axis control system on a conventional CNC ... more This paper presents the implementation of an exter-nal axis control system on a conventional CNC ma-chine so that the machine can be actively controlled in response to sensors such as vision and force. The controller that runs on an external computer has di-rect access to the CNC controller for machine posi-tion sensing. The control signals to the machine are sent through purpose built circuitry via the machine’s manual pulse generator (MPG) inputs. To demon-strate the accuracy and performance of the control system, it was used to visually track the profile of a mandrel used for shear spinning. The implemented system eliminates the parallax error and the need to use an accurate pixel resolution. The raw tracking data is processed by a curvature detection algorithm that detects linear and circular segments and segment transitions. The results show that the visual tracking system provides accurate tracking results that are well within the tolerances used in the industry.

The work presents a cost-effective custom-made data logging system for in-vehicle use. Based on t... more The work presents a cost-effective custom-made data logging system for in-vehicle use. Based on the required bandwidth and accuracy of the torque signal a real-time data acquisition system for long-term data logging of torque signal has been designed and implemented. The system is based on a computer running Windows CE 3.0 operating system. Filtered input signal is sample by over-sampling data acquisition system. Data reduction is achieved by decimation and data compression. Three data compression methods are compared: two methods based on zero-order and first-order predictors and a piecewise linear approximation method followed by run-length and Huffman coding. Several error bands have been investigated in the data compression methods. Test result show that a system with 1 GB flash card can store over 10000 hrs of drive shaft load history data allowing signal reconstruction with satisfactory accuracy.

International Conference on Mechatronics and Machine Vision in Practice, 1997

The paper describes the replacement of the controller for a PUMA 512 robot with a newly designed ... more The paper describes the replacement of the controller for a PUMA 512 robot with a newly designed PC based controller employing real-time direct control of the six articulated joints. The original mechanical structure of the PUMA 512 has been retained. The control software has been implemented by user programs written in C and C++ programming languages. The hardware of the

1995 IEEE International Conference on Systems, Man and Cybernetics. Intelligent Systems for the 21st Century, 1995

A novel active-vision system is presented in this paper for moving-object recognition. The propos... more A novel active-vision system is presented in this paper for moving-object recognition. The proposed system is a natural extension of the static-object recognition system developed earlier in the authors' laboratory. Pre-marking, via circular markers placed on the objects, and active detection, via a camera mounted on a robot, comprise the two principles of the recognition technique. The primary steps of the image-acquisition and recognition procedure are: elliptical shape fitting to a detected marker's boundary, estimation of this marker's 3D-location and orientation, and object standard-view matching. Following the description of the static case, the moving-object recognition technique is introduced with a special focus on the solution of the orientation-duality problem. Utilizing motion information, the duality problem is solved by the acquisition of two consecutive images. An experimental example is given to demonstrate the feasibility of the overall proposed recognition system

Proceedings 2003 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2003), 2003

A reliable system that uses hand gestures to control a wheelchair is presented. The control actio... more A reliable system that uses hand gestures to control a wheelchair is presented. The control actions are generated by gestures of a bare or gloved hand. The gestures are recognized and identified in a scale, position, orientation and skin color independent manner. Yet the position and orientation of the hand gesture for motion control are used for speed and steering angle control. The interface works equally well with either of the hands and can be interchanged anytime without any changes to the system. The hand gestures are organized in a hierarchy taking into account the ergonomics, reliability of identification and the mode of operation. The modes of operation are; the manual mode and the map mode. The results presented show the behavior of the wheelchair in response to manual and map mode hand gesture commands. The system has been put to test by persons of different hand shapes and proved to be extremely reliable.

Proceedings 2003 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2003), 2003

A new method to identify spatial gradients of edges using grey level variations is presented. Thi... more A new method to identify spatial gradients of edges using grey level variations is presented. This method is especially useful when camera resolution is low. A high accuracy edge profile can be obtained by blending the extracted edge gradients and edge positions. This paper experimentally proves that the grey level gradient is a function of the spatial gradient of a profile that transits across a pixel. A calibration equation is established relating the grey level gradients and edge gradients. This equation can be used to extract the gradients of an unknown profile. As positions along the profile are readily available, by blending in the profile gradients, an object profile with increased accuracy can be obtained. Experiments were conducted on a specially built rig to verify the validity of the theoretical formulations. An interpolation algorithm is presented to demonstrate how improved accuracy can be obtained using gradient blending.

Proceedings 2003 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2003), 2003

... response in block execution mode. The performance of the active axis control system is demon-... more ... response in block execution mode. The performance of the active axis control system is demon-strated by tracking the profile of a mandrel mounted on a CNC lathe using visual feedback. This automatic profile scanning system ...

Proceedings 2003 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2003), 2003

Use of visual scanning to automatically generate an accurate tool path is presented. Emphasis is ... more Use of visual scanning to automatically generate an accurate tool path is presented. Emphasis is on combining low resolution vision with visual control of a precision machine tool to attain the accuracy required for shear spinning. A simplified edge detection method is used to obtain the required sub-pixel accuracy of the mandrel profile. Two different tool paths are generated using two different methods. First, a part program is generated assuming all data points extracted during scanning are joined by straight lines. Second, assuming that all segments of the mandrel profile consists of circular sections and straight line segments, a curvature detection algorithm is used to identify segments. Then the segments are put together in a part program. Dimensional accuracy of components spun using these two methods are compared with the actual profile. While both methods gave acceptable results, the segment extracted tool path produced a component with superior dimensional accuracy.

Proceedings Fourth Annual Conference on Mechatronics and Machine Vision in Practice, 1997

2006 9th International Conference on Control, Automation, Robotics and Vision, 2006

... Point (ICP) algorithm [1], [2] and its variants, the idea borrowed from vision community. ...... more ... Point (ICP) algorithm [1], [2] and its variants, the idea borrowed from vision community. ... Although the techniques based on Kalman filter are considered efficient but have number of ... a relatively much smaller set of end points of line segments, therefore memory requirements are ...

Proceedings of the 2003 IEEE International Symposium on Intelligent Control ISIC-03, 2003

Geometric properties are used to reliably identify gestures of a bare or gloved hand. A set of op... more Geometric properties are used to reliably identify gestures of a bare or gloved hand. A set of optimum hand gestured were experimentally identified. The hand gestures are used to issue commands to a wheelchair. The effect of skin color is eliminated by using a back-lit surface. The system is scale, position and orientation invariant. Yet position and orientation of two hand gestures are used to issue motion control commands in two modes; manual and auto. In manual mode the position and orientation of a selected hand gesture are used for speed and steering control. The interface works well with either of the hands and can be interchanged anytime without any changes to the system. The hand gestures are organized in a hierarchy taking into account the ergonomics, reliability and the mode of operation. The manual and auto mode operations are demonstrated by presenting the results showing each mode of operation.

IEEE International Conference on Robotics and Automation, 2004. Proceedings. ICRA '04. 2004, 2004

This paper presents a curvature based hand shape recognition method using images of a hand. The c... more This paper presents a curvature based hand shape recognition method using images of a hand. The curvatures extracted from hand shape contours are converted to a non-dimensional quantity. Combining the contour geometry with the non-dimensional quantities, signatures are generated for template hand shapes. These template signatures are used to recognize hand shapes embedded in newly acquired image contours. The method

2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004

This paper presents a generic approach to model the noise covariance associated with discrete sen... more This paper presents a generic approach to model the noise covariance associated with discrete sensors such as incremental encoders and low resolution analog to digital converters. The covariance is then used in an adaptive Kalman Filter that selectively and appropriately carries out measurement updates. The temporal as well as system state measurements are used to predict the quantization error of the measurement signal. The effectiveness of the method is demonstrated by applying the technique to incremental encoders of varying resolutions. Simulation of an example system with varying encoder resolutions is presented to show the performance of the new filter. Results show that the new adaptive filter produces more accurate results while requiring a lower resolution encoder than a similarly designed conventional Kalman filter, especially at low velocities.

2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004

Comparison of advantages and disadvantages of control methods used in nonlinear systems is presen... more Comparison of advantages and disadvantages of control methods used in nonlinear systems is presented. To take advantage of both adaptive and robust control methods, a novel method which switches between the two is proposed. Robust control is used during transients and situations where parameters are uncertain. During steady state operations, adaptive control is used. Switching between the two methods is carried out based on the standard deviation of the estimated parameter vector. The method has been implemented on a 2 DOF articulated robot. Experimental results are presented to prove the robustness and the accuracy of the new control method.

2006 International Conference on Mechatronics and Automation, 2006

We present a new and completely probabilistic approach to extract the unknown motion model of an ... more We present a new and completely probabilistic approach to extract the unknown motion model of an autonomous wheelchair. This method is, however, general and can be applied to any mobile robot. Particle filter based methods are very popular for localization and navigation of mobile robots. These methods use motion model for the prediction of robot states when a control action

Quality and Reliability Engineering International, 1986

Determination of the optimum equipment replacement policy and time is of great economic importanc... more Determination of the optimum equipment replacement policy and time is of great economic importance. After a brief survey of the models which have been used for decision making, the paper looks at methods for detecting and quantifying growth of failure frequency (peril rate) in repairable equipment. It examines the trend detection methods of Laplace and Mann when the peril rate varies as a power of equipment age and also applies them to some actual field failure data. An economic model is developed, based on total discounted future cost and providing for ongoing future technological growth. The cost comprises not only the conventional cost of ownership, but also the shortfall between an equipment's achieved benefit and that which would be achieved by an ideal equipment in the same demand environment. The inclusion of this shortfall, called 'incapacity cost', enables the replacement decision to be based not only on the deterioration of equipment but also on its performance inadequacy and on the availability of technological improvement in present and future challengers. The formulation of the cost model is such that for both a single-replacement finite planning horizon and an infinite horizon the total discounted future cost is readily computed for a range of alternative replacement times and the optimum replacement programme thereby determined. The sensitivity of total cost to the replacement times and the sensitivity of the optimum times to the variability of assumed input data are easily examined. The application of the model to traffic signal equipment is described. In this application the total cost is shared between the nominal owner of the equipment and the community.

The present work describes the development and partial validation of a mathematical model of a hy... more The present work describes the development and partial validation of a mathematical model of a hydraulically actuated electronically controlled unit injector (HEUI). The HEUI analyses include submodels of the solenoid, hydraulic differential valve (HDV), intensifier and injector subsystems. It has been implemented using the MATLAB/SIMULINK graphical software environment. The modeled HEUI is a compact, flexible diesel injector developed at the

Proceedings of The Institution of Mechanical Engineers Part D-journal of Automobile Engineering, 2005