Mehmet Sahinkaya

Mehmet Sahinkaya
Kingston University London · School of Mechanical and Automotive Engineering

About

121
Publications
103,474
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,327
Citations
Introduction
Mehmet Sahinkaya currently works at Kingston University London as the Head of Department of Mechanical Enginering. He has made seminal contributions to the study of machine systems, inverse dynamic analysis, dynamics, control and modelling of nonlinear multi-physics systems, and robotics. He pioneered an adaptive control technique using magnetic bearings to control vibrations in rotating machines. His research in the dynamics and control of complex non-linear mechatronic systems has been recognised through prizes and awards and has published over 140 journal and conference papers.
Additional affiliations
November 2013 - November 2016
University of Bath
Position
  • Professor
May 2000 - October 2013
University of Bath
Position
  • Reader in Mechanical Engineering
September 1982 - December 1987
University of Strathclyde
Position
  • Lecturer

Publications

Publications (121)
Conference Paper
Full-text available
An electrocardiogram (ECG or EKG) signal represents various information about the heart electrical activities. The patterns differ based on the heart characteristics and vary from one person to another. ECG features become increasingly popular as useful tool in biometric recognition in particular for the early diagnosis of cardiac health issues suc...
Chapter
Full-text available
People who use the thumb in repetitive manipulation tasks are likely to develop thumb related impairments from excessive loading at the base joints of the thumb. Biologically informed wearable robotic assistive mechanisms can provide viable solutions to prevent occurring such injuries. This paper tests the hypothesis that an external assistive forc...
Article
In this paper, a feed-forward deep neural network (DNN) and automated search method for optimum network structure are developed to control an active suspension system (ASS). The network was trained through supervised learning using the backpropagation algorithm. The training data were generated from an optimal proportional–integral–derivative contr...
Article
Wind blades are the most expensive parts of wind turbines made from fibre reinforced polymer (FRP) composites. The blades play a critical role on the energy production, but they are prone to damage like any other composite components. Leading Edge (LE) erosion of the wind turbine blades is one of the common damage, causing a reduction in the Annual...
Article
Active magnetic bearing systems provide contact-free rotor levitation, which allows near frictionless rotation and high rotational speeds when they operate normally. Under certain operational conditions, a transient fault, overload condition, or disturbance may occur. Touchdown bearings or bushings are therefore implemented in such systems to preve...
Chapter
Full-text available
This paper presents a design optimization approach to minimize the volume of a radial Active Magnetic Bearing (AMB) by comparing Genetic Algorithm (GA) and Pattern Search (PS) methods. The flexible rotor dynamic analysis is performed to determine AMBs dynamic load under different unbalance cases. Preliminary design parameters are generated and resu...
Conference Paper
Full-text available
In this paper, a novel analytical tuning methodology for PID gains, based on Linear Quadratic Regulator (LQR) optimal control, for linear systems is developed. The proposed methodology uses once LQR in order to obtain different PID configurations (P, PI, PD, PID). The effectiveness and the applicability of the proposed methodology are demonstrated...
Conference Paper
Full-text available
This paper presents a design optimization approach to min- imize the volume of a radial Active Magnetic Bearing (AMB) by com- paring Genetic Algorithm (GA) and Pattern Search (PS) methods. The flexible rotor dynamic analysis is performed to determine AMBs dynamic load under different unbalance cases. Preliminary design parameters are generated and...
Article
Full-text available
This paper deals with the fundamental mechanical engineering challenge of mechanism design. While there is a significant body of research associated with mechanism design there are few, if any, approaches that consider kinematic synthesis and optimisation of dynamic performance in an integrated manner. To address this gap, this paper presents a lay...
Conference Paper
PID controller is the most common control method used in many industrial applications, and tuning of the PID gains is still an active research area despite the availability of different tuning methods in the literature. This paper aims to demonstrate a comparison between two different PID tuning methods which are based on full state feedback Linear...
Article
Full-text available
This article presents an optimization technique to develop minimum energy consumption trajectories for redundant/hyper-redundant manipulators with predefined kinematic and dynamic constraints. The optimization technique presents and combines two novel methods for trajectory optimization. In the first method, the system’s kinematic and dynamic const...
Article
Full-text available
This paper addresses the problem of controlling the hopping height and stride length of a monoped hydraulic robot. Hopping over discontinuous, rough terrain with limited surfaces suitable for foot placement requires a controller capable of adjusting the hop height and landing foot position of the robot on each step. This motivates the need for an a...
Article
Full-text available
The unique musculoskeletal structure of the human hand brings in wider dexterous capabilities to grasp and manipulate a repertoire of objects than the non-human primates. It has been widely accepted that the orientation and the position of the thumb plays an important role in this characteristic behavior. There have been numerous attempts to develo...
Article
Full-text available
Rotary-wing unmanned aerial vehicles (UAVs) have the ability to operate in confined spaces and to hover over point of interest, but they have limited flight time and endurance. Conventional contact-based charging system for UAVs has been used, but it requires high landing accuracy for proper docking. Instead of the conventional system, autonomous w...
Article
Full-text available
Energy use in internal combustion engine passenger vehicles contributes directly to CO 2 emissions and fuel consumption, as well as producing a number of air pollutants. Optimizing the vehicle velocity by utilising upcoming road information is an opportunity to minimize vehicle energy use without requiring mechanical design changes. Dynamic program...
Article
This paper presents an optimization technique to develop minimum energy consumption trajectories for redundant/hyper-redundant manipulators with pre-defined kinematic and dynamic constraints. The optimization technique presents and combines two novel methods for trajectory optimization. In the first method, the system’s kinematic and dynamics const...
Conference Paper
Full-text available
There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of dexterous capabilities. However, these robotic hands often suffer from a lack of comprehensive understanding of the musculoskeletal behavior of the human thumb with integrated foldable palm. This paper proposes a novel kinematic model to analyze the im...
Article
Full-text available
A novel rotor topology is proposed with the goal of reducing vibration in high speed rotor systems. Reduction in vibration at critical speeds is targeted. In essence, the novel topology consists of a hollow tube rotor coupled to a secondary non-rotating shaft located concentrically within the primary rotor. The two shafts are linked via a number of...
Conference Paper
Full-text available
Humans demonstrate remarkable capabilities to use a variety of grasp strategies for a given object depending on the context of the task-often referred to as grasp affordances in dexterous hands. The interplay among the nervous system, the morphology of the human hand, and the properties of the object to demonstrate these advanced grasp affordance s...
Article
A novel topology based on active magnetic bearing coupling for reducing synchronous vibration in rotors at critical speeds is outlined. The topology consists of a hollow rotor with a flexible concentric secondary shaft running along its length. Between the two shafts are one or more actively managed couplings. A design of a test rig to illustrate t...
Article
Active Magnetic Bearings (AMBs) have many advantages such as allowing near frictionless rotation and high rotational speeds. Touchdown bearings (TDBs) are a requirement in AMBs to prevent system damage under certain conditions, such as high loads, transient faults, or external disturbances. These conditions may lead to rotor/TDB contact. The AMBs m...
Conference Paper
This paper presents a new method for designing optimized excitation trajectories for the estimation of robot manipulator model parameters. Current optimization methods require large number of parameters and solving nonlinear optimization problems. This work utilizes the Schroeder Phased Harmonic Sequence (SPHS) in the trajectory design process whic...
Conference Paper
Full-text available
This paper presents a new method to generate point-to-point (PTP) trajectories, such as the ones used by robots or CNC machines, using an exponential function as the basis for the trajectory profile. The method is based on adding a series of time-delayed third-order exponential functions to generate an approximation to the trapezoidal velocity prof...
Conference Paper
Under contact-free levitation, rotors supported by active magnetic bearings have many advantages such as allowing near frictionless rotation and high rotational speeds. They also provide the designer the capability to achieve increased machine power density. However, magnetic bearings possess limited load capacity and operate under active control....
Conference Paper
Rotating machines may, for reasons of gyroscopic coupling and aerodynamic influences, exhibit speed dependent characteristics. For systems that incorporate active magnetic bearings (AMBs) for rotor levitation, a range of control strategies are available for implementation to achieve desired closed loop dynamic characteristics. Over a large operatin...
Conference Paper
Full-text available
The main contribution of this paper is a new step-time controller for a vertically hopping robot leg capable of meeting a demanded step-time instantaneously, meaning within a single hop. The ability to perform hops of an arbitrary and changing size accurately forms the motivation behind the work done here. This would allow control of a running robo...
Article
Hardware-in-the-loop transmission testing requires precise speed and torque tracking of the actuators that emulate the engine and vehicle dynamics. System-inversion-based feedforward controllers offer a solution, but they do not work for non-minimum-phase systems. Preview filters can provide stable approximate inversion of non-minimum-phase systems...
Conference Paper
Planar control is an important first step in the development of more complex running robots. This extended abstract describes a technique for control of a one-legged planar robot hopping over discontinuous surfaces. In simulations the robot is tasked with traversing across terrain which provides limited surface for foot placement. The robot has to...
Conference Paper
The use of magnetic bearings allows rotor dynamic systems to be developed for high speed applications, including low pressure/vacuum environments. They provide an alternative to conventional journal, rolling element and gas bearings. The benefits of using magnetic bearings are well documented in terms of low friction operation, together with contro...
Conference Paper
Research on running robots has generally focussed on the steady-state. When the ground has limited foot placement surfaces or there are sudden changes in height then steady-state running is not possible. It becomes necessary to make step-by-step adjustments to place the foot. In this paper a mass-spring-damper model of a robot’s leg is used to deve...
Conference Paper
This paper presents a nonlinear variable bias controller for an active magnetic bearing (AMB). The nonlinear bearing force is analyzed theoretically and the control current for various bias current settings is derived from the nonlinear bearing equation. Then the power consumption is minimized to obtain the optimum bias current expression analytica...
Article
Full-text available
Today there is a big interest in reducing the maintenance costs and in increasing the reliability of machines in continuous operation. Therefore, maintenance on condition is used. State-of-the-art is a trend analysis and a fault prediction made only based on sensor signals and stochastic methods. The identification possibilities of this technique a...
Article
This paper considers two issues in the vibration of rotating machines, namely, control of rotor vibration and control of the forces transmitted to the base. An adaptive multi-objective method is developed to tackle these issues simultaneously using magnetic bearings. A two-stage weighting strategy is developed, involving base weightings calculated...
Article
Full-text available
This paper presents a method for developing robot trajectories that achieve minimum energy consumption for a point-to-point motion under kinematic and dynamic constraints. The method represents trajectories as a fourth degree B-spline function. The parameters of the function are optimised using a multi-parametric optimization algorithm. Actuator to...
Conference Paper
This paper introduces an adaptive bias current control method for an active magnetic bearing (AMB). The bearing force is analyzed theoretically, and the dynamic performance of the magnetic bearing for various bias currents is discussed. Then power consumption is analyzed and the optimum bias current that minimizes power consumption is derived. A no...
Conference Paper
This paper presents a method to develop minimum energy trajectories for redundant/hyper-redundant manipulators with pre-defined kinematic and dynamic constraints. The optimal trajectory planning uses fifth order B-spline functions to represent the Cartesian coordinates of the end-effector and angles of the redundant links. The actuator torques are...
Article
Full-text available
The paper considers three issues in flexible rotor and magnetic bearing systems, namely control of rotor vibration, control of transmitted forces, and prevention of rotor contact with auxiliary bearings. An adaptive multi-objective optimization method is developed to tackle these issues simultaneously using a modified recursive open loop adaptive c...
Article
Full-text available
The paper describes an experimental assessment of the tran-sient performance of a multi-objective adaptive approach to the control of flexible rotors previously presented by the authors. The approach is applicable to any form of controllable bearings or actuators. In the case reported here, the rotor is supported by active magnetic bearings (AMBs)....
Conference Paper
During fault conditions, rotor displacements in magnetic bearing systems may potentially exceed safety/operating limits. Hence it is a common design feature to incorporate auxiliary bearings adjacent to the magnetic bearings for the prevention of rotor/stator contact. During fault conditions the rotor may come into contact with the auxiliary bearin...
Article
Auxiliary bearings are used in many rotor systems, e.g. those with active magnetic bearings. In a case of a contact with the auxiliary bearing, high impact forces and wear are possible. Therefore the auxiliary bearings have to be replaced after a certain number of contact events. This is very costly and often needs complete dismantling of the rotor...
Article
Full-text available
To prevent rotor/stator contact in a rotor/magnetic bearing system, auxiliary bearings may be located along the shaft and at the magnetic bearings. Rotor responses after a contact event may include periodic trapped modes where repeated contact may lead to highly localized thermal stresses. This paper considers an active auxiliary bearing system wit...
Article
Full-text available
This paper demonstrates a new form of Input Shaping for vibration reduction applied to robotic systems that manipulate flexible loads. The method is based on using an exponential function to define asymptotic and vibration-free trajectories for the flexible system. The required control input is calculated analytically by using inverse dynamics whic...
Article
Full-text available
The design of a smart rotating machine involves the integration of controllable bear-ings, actuators, and sensors to measure a defined set of physical variables, an on-line adaptive controller, a control algorithm to achieve the desired performance, and an algorithm to re-configure the system in the event of faults. This review discusses each of th...
Article
Full-text available
Ocean waves are a huge, largely untapped energy resource, and the potential for extracting energy from waves is considerable. Research in this area is driven by the need to meet renewable energy targets, but is relatively immature compared to other renewable energy technologies. This review introduces the general status of wave energy and evaluates...
Article
Full-text available
Auxiliary bearings are used to prevent rotor/stator contact in active magnetic bearing systems. They are sacrificial components providing a physical limit on the rotor displace- ment. During rotor/auxiliary bearing contact significant forces normal to the contact zone may occur. Furthermore, rotor slip and rub can lead to localized frictional heati...
Article
Full-text available
It was shown in an earlier paper that the authors' recursive open loop adaptive control strategy can be used as the basis for an adaptive multi-objective control strategy to satisfy design cri-teria for rotor-bearing systems involving the relative weighting of forces transmitted to the foundation and rotor vibration. This paper describes a compleme...
Article
Full-text available
A novel method is described to implement noncausal feedfor-ward compensators causally, i.e. without requiring any future value of the reference input trajectory. A hardware-in-the loop test facility developed for continuously variable transmissions is utilized in this paper. The test facility includes two induction motors to emulate engine and vehi...
Chapter
Full-text available
Vibrations associated with external disturbances and rotor faults, such as cracks, usually exhibit themselves as harmonic components of the synchronous frequency. The essence of the multi-frequency form of the synchronous recursive open loop adaptive controller (ROLAC) is that it can minimise a number of vibration components simultaneously, for exa...
Conference Paper
Full-text available
The purpose of the paper is to improve the dynamic performance of a mechanism used in a packaging machine in order to run the system at higher speeds with lower vibration and noise levels. A method of synthesising a velocity demand signal as a function of crank position (i.e. cam function) is demonstrated for a prototype mechanism and drive system....
Article
Full-text available
This paper describes a unique, computer-based, mechanism design strategy that takes into account both kinematic and dynamic performance criteria at the synthesis stage of the design process. The strategy can be used to investigate improvements in the design of any existing mechanism with geometric redundancy in its output path. By iteratively varyi...
Article
Full-text available
This paper considers the design of an actively con-trolled auxiliary bearing system for use with mag-netic bearings. During rotor/auxiliary bearing con-tact large frictional contact forces can lead to signif-icant thermal stresses. Furthermore, the non-linear nature of the contact can induce unfavourable rotor dynamic behaviour. An active auxiliary...
Article
Full-text available
Large rotor vibrations in magnetic bearing systems often occur during fault conditions. To prevent rotor/stator contact, auxiliary bearings are usually incorporated. During rotor/auxiliary bearing contact significant contact forces may occur. Furthermore, tangential forces due to rotor slip/rub may cause localised thermal stresses. Rotor dynamic re...
Article
Full-text available
Magnetic bearings systems usually incorporate auxiliary bearings so that rotor/stator contact is prevented. The rotor must then make contact with the auxiliary bearings if any clearance boundaries are exceeded. It is then possible for a rotor with a given unbalance condition to exhibit either contact free levitation or to become trapped in various...
Article
Full-text available
Woodpecker can be modelled as a low-inertia hammer. It uses the angular momentum of its body, generated by contraction of its leg muscles, to accelerate its head towards the tree, which it is pecking. It appears to peck at a resonant frequency.
Article
Full-text available
A method to predict unknown external disturbances and modelling errors for trajec-tory tracking of non-linear systems is presented. The technique involves dual inverse non-linear dynamics modelling based on Lagrangian dynamics and the use of redundant coordinates incor-porating Lagrange multipliers. The first inverse dynamics model is a conventiona...
Article
Full-text available
Active magnetic bearings (AMBs) offer contact-free and frictionless support of rotating machinery. However, because of their limited force capacity, they have to incorporate retainer bearings to protect the rotor and stator laminations against high-amplitude vibration levels. Efficient modeling of contact dynamics is important for the design of ada...
Article
A novel method for predicting the ultimate steady-state vibration amplitudes from measured transient responses in multi-input, multi-output flexible rotor/magnetic bearing systems is presented. The technique is based around a multi-level wavelet coefficient analysis with in-built transient system dynamics. The relation between an input disturbance...
Article
A novel method for transient rotor/ active magnetic bearing control using sampled wavelet coef cients is proposed. Control currents are formulated in the wavelet transform domain, prior to signal reconstruction. The wavelet based controller is designed from target transient responses due to step changes in wavelet co- ef cients of applied forces. T...
Article
Full-text available
We introduce an adaptive variable bias current control scheme to minimize the energy consumption of magnetic bearings without altering the dynamic performance. We developed analytical expressions for the optimum bias current settings for both differential and unidirectional modes of operation as a function of the orbit size and the desired bearing...
Article
The aim of the work described in this paper is to improve the dynamic performance of a one-degree-of-freedom packag ing mechanism through demand signal shaping to minimize the pea k to peak motor torque. This enables the mechanism to operate a t higher speeds with lower vibration and noise levels, and hen ce with higher accuracy. Initial experiment...