The human hand has evolved to be remarkably good at skillfully manipulating objects. This manipulation requires knowledge of the dynamic properties of an object, which is represented in the central nervous system (CNS) by what has been referred to as an internal model. Internal models are neural representations of the predicted behaviour of objects or limbs with a known state in response to a given motor command. Our ability to successfully manipulate a wide variety of objects suggests that the CNS maintains multiple internal models of familiar object dynamics. People are able to both recruit these models for use when an object is grasped and to rapidly switch to another model when the object is exchanged. The purpose of this study was to investigate how internal models of objects are accessed and used for action. In experiment 1, subjects learned to move a cursor to a target by manipulating a robotic arm with complex dynamics. We used event-related fMRI to measure the neural activity associated with grasping the robot handle in preparation for movement. In comparison to control tasks, subjects showed significant neural activation in the ipsilateral cerebellum and the contralateral primary motor and supplementary motor areas, suggesting the likely involvement of these areas in recruitment of internal models. In experiment 2, we used a precision lifting task to investigate how the internal representation of weight asymmetry transfers across changes in hand, hand orientation and object orientation. Subjects demonstrated positive transfer in all cases when the hand was rotated, indicating that internal models of objects can be adapted to accommodate changes in hand orientation. When the object was rotated, positive transfer was seen only when the hand also rotated, suggesting that this change in hand orientation facilitated mental rotation of the object. Overall, these results support the idea that people maintain an internal representation of object dynamics but can not always link this model to the configuration of the object in space. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2007-08-29 10:57:23.511

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During transport of hand-held objects, the grip force is modulated in parallel with the load force changes. The control scheme underlying this grip-load force coupling involves subtle interplay between feedforward and feedback mechanisms. Based on internal models of the motor system and object properties, the load force can be predicted and the GF motor command can be specified in a feedforward manner. Moreover, during the course of arm movement, the CNS is informed by sensory feedback about mechanical events such as the lift-off of the object, slippage or excessive grip force. This information is used to correct the motor commands and to update the internal model of the motor apparatus and object. In this thesis, three experiments were conducted to examine the relative contributions of sensory-driven and anticipatory control of GF adjustments during cyclic vertical movement with a hand-held load. The main point was to assess whether internal models underlying the grip-load force coupling are robust when the environmental context was changed or when the sensory feedback was suppressed. Two experiments in parabolic flight were conducted to study the effects of a change in gravity on the dynamics of prehension. The main perturbation was that the novice subjects applied unnecessarily high safety margins during their first trial at 0 and 1.8 g in order to secure the grasp insofar as the gravitational component of the load force was unpredictable. By contrast, the temporal coupling between GF and LF was maintained regardless of the gravity conditions because the inertial component of the load could be still predicted from the arm motor command (efference copy). In the second study performed during parabolic flight, we have observed that the subjects were able to exert the same grip force for equivalent load generated either by a change of mass, gravity or acceleration despite the fact that it requires different arm motor commands. These two experiments brought further evidence that the predictive mechanisms largely contribute to the GF adjustment. Static forces such gravity are taken into account in the motor plan allowing adequate motor command and precise prediction of the incoming load force change. The GF output would depend on the precision of this prediction that can be evaluatedonly after the movement onset through sensory information about the actual state of the system. The third experiment performed in this thesis studied the role of cutaneous afferents in object manipulation by anesthetizing the thumb and index finger. In addition to their phasic slip-detection function, the cutaneous afferents are required for setting the background level of the grip force. Actually, in absence of tactile feedback, the temporal coupling between the grip and load forces is maintained but the mean magnitude of GF progressively decreases leading to object slipping. It is hypothesized that accumulating error occurred in the LF prediction leading to inadequate level of GF. Cutaneous afferents are thus required to correct and maintain the internal model of the arm-hand object system.

During transport of hand-held objects, the grip force is modulated in parallel with the load force changes. The control scheme underlying this grip-load force coupling involves subtle interplay between feedforward and feedback mechanisms. Based on internal models of the motor system and object properties, the load force can be predicted and the GF motor command can be specified in a feedforward manner. Moreover, during the course of arm movement, the CNS is informed by sensory feedback about mechanical events such as the lift-off of the object, slippage or excessive grip force. This information is used to correct the motor commands and to update the internal model of the motor apparatus and object. In this thesis, three experiments were conducted to examine the relative contributions of sensory-driven and anticipatory control of GF adjustments during cyclic vertical movement with a hand-held load. The main point was to assess whether internal models underlying the grip-load force coupling are robust when the environmental context was changed or when the sensory feedback was suppressed. Two experiments in parabolic flight were conducted to study the effects of a change in gravity on the dynamics of prehension. The main perturbation was that the novice subjects applied unnecessarily high safety margins during their first trial at 0 and 1.8 g in order to secure the grasp insofar as the gravitational component of the load force was unpredictable. By contrast, the temporal coupling between GF and LF was maintained regardless of the gravity conditions because the inertial component of the load could be still predicted from the arm motor command (efference copy). In the second study performed during parabolic flight, we have observed that the subjects were able to exert the same grip force for equivalent load generated either by a change of mass, gravity or acceleration despite the fact that it requires different arm motor commands. These two experiments brought further evidence that the predictive mechanisms largely contribute to the GF adjustment. Static forces such gravity are taken into account in the motor plan allowing adequate motor command and precise prediction of the incoming load force change. The GF output would depend on the precision of this prediction that can be evaluatedonly after the movement onset through sensory information about the actual state of the system. The third experiment performed in this thesis studied the role of cutaneous afferents in object manipulation by anesthetizing the thumb and index finger. In addition to their phasic slip-detection function, the cutaneous afferents are required for setting the background level of the grip force. Actually, in absence of tactile feedback, the temporal coupling between the grip and load forces is maintained but the mean magnitude of GF progressively decreases leading to object slipping. It is hypothesized that accumulating error occurred in the LF prediction leading to inadequate level of GF. Cutaneous afferents are thus required to correct and maintain the internal model of the arm-hand object system.

This thesis deals with the problem of control system design for power electronic controllers when high performance is desired despite unaccounted for internal and external conditions. Factors such as parameter variations, operating condition changes, and filtering and measurements delays, may adversely impact the performance of a circuit whose controller design is not immune to external and internal disturbances. The thesis explores the method of internal model design as a viable approach for designing controllers with superior performance despite system variations. Following a presentation of the theoretical background of the internal model design, the thesis considers two examples of state variable models, improving the stability of a voltage source converter and speed control of an induction motor. Conclusions show the new control system is more stable and offers better controllability despite unexpected system variations, compared to classical control system.

The demand of modern technology is highly required by humans. The Linear motor, one of the most significant inventions, has been playing a vital role in driving component. The Structure of the gantry is the main design and the requirement of high bandwidth and rigidity. Twin-linear motors coupled and paralleled with machining beam are to realize one degree-movement. To prevent the marching beam from deformation, the synchronized motion control becomes an important technology for this machine. This thesis solves the problem of the mechanism coupling by using of the synchronized master command approach which integrates the decouple control and internal model control and taking the mechanism beam as an uncertainty. Both system uncertainties and unknown disturbances occurring in actual implementation need to be carefully considered. And the synchronized motion control of the two linear servo systems with mechanism will be investigated. Better synchronization performance for two motors can therefore be anticipated.

Title: Solvency Internal models Author: Mgr. Ing. Jakub Mertl Abstract: The subject of thesis is assessment of calculation methods on capital adequacy of currently implemented regulation in insurance industry called Solvency II. The aim of the thesis is to build up a partial internal model fulfilling the condition of Solvency II. The thesis deals with the premium and reserve risks that are essential part of non-life business. Different approaches of risk assessment are described and aggregation of those risks as well. An important part of the thesis is a numerical example illustrating presented methods.

Most practical control problems must deal with constraints imposed by equipment limitations, safety considerations or environmental regulations. While it is often beneficial to maintain operation close to the limits in order to maximize profit or meet stringent product specifications, the violation of actuator constraints during normal operation can result in serious performance degradation (sometimes instability) and economic losses. This thesis is concerned with the development of control strategies for multivariable systems which systematically account for actuator constraints while guaranteeing closed-loop stability as well as graceful degradation of non-linear performance. A novel anti-windup structure is proposed which combines the efficiency of conventional anti-windup schemes with the optimality of model predictive control (MPC) algorithms. In particular, the classical internal model control (IMC) law is enhanced for optimal performance by incorporating an on-line optimization. The resulting control scheme offers both stability and performance guarantees with moderate computational expense. The proposed optimizing scheme has prospects for industrial applications as it can be implemented easily and efficiently on programmable logic controllers (PLC).

Wrist and forearm motion is governed both by its dynamics and the control strategies employed by the neuromuscular system to execute goal oriented movement. Two experiments were conducted to increase our understanding of wrist and forearm motion. The first experiment involved 10 healthy subjects executing planned movements to targets involving all three degrees of freedom (DOF) of the wrist and forearm, namely wrist flexion-extension (FE), wrist radial-ulnar deviation, and forearm pronation-supination (PS). A model of wrist and forearm dynamics was developed, and the recorded movements were fed into the model to analyze the movement torques. This resulted in the following key findings: 1) The main impedance torques affecting wrist and forearm movements are stiffness and gravity, with damping and inertial effects contributing roughly 10% of the total torque. 2) There is significant coupling between all degrees of freedom (DOF) of the wrist and forearm, with stiffness effects being the most coupled and inertial effects being the least coupled. 3) Neglecting these interaction torques results in significant error in the prediction of the torque required for wrist and forearm movements, suggesting that the neuromuscular system must account for coupling in movement planning. A second experiment was conducted in which 10 different healthy subjects pointed to targets arranged on a plane in front of the subjects. This pointing task required two DOF, but subjects were allowed to use all three DOF of the wrist and forearm. While subjects could have completed the task with FE and RUD alone, it was found that subjects recruited PS as well. Hypotheses regarding why subjects would recruit PS even though it was not necessary included the minimization of a number of cost functions (work, effort, potential energy, path length) as well as mechanical interaction between the DOF of the wrist and forearm. It was found that the pattern of PS recruitment predicted from the mechanical interaction hypothesis most closely resembled the observed pattern. According to this hypothesis, the neuromuscular system uses a simplified 2 DOF model of the joints most critical to the task (FE and RUD) to plan the task, while leaving the third DOF (PS) uncontrolled. The resulting interaction torques create the observed pattern of PS movement.

This thesis develops techniques for the design and analysis of controllers to achieve sub-micron accuracy on the position of electron beams for the optimal performance of synchrotrons. The techniques have been applied to Diamond Light Source, the UK's national synchrotron facility. Electron beam motion in synchrotrons is considered as a large-scale, two-dimensional process and by using basis functions, controllable modes of the process are identified which are independent and allow the design to be approached in terms of a family of single-input, single-output transfer functions. This thesis develops techniques for the design and analysis of controllers to achieve sub-micron accuracy on the position of electron beams for the optimal performance of synchrotrons. The techniques have been applied to Diamond Light Source, the UK's national synchrotron facility. Electron beam motion in synchrotrons is considered as a large-scale, two-dimensional process and by using basis functions, controllable modes of the process are identified which are independent and allow the design to be approached in terms of a family of single-input, single-output transfer functions. In this thesis, loop shaping concepts for dynamical systems are applied to the two-dimensional frequency domain to meet closed loop specifications. Spatial uncertainties are modelled by complex Fourier matrices and the closed loop robust stability, in the presence of spatial uncertainties is analysed within an Integral Quadratic Constraint framework. Two extensions to the unconstrained, single-actuator array controller design are considered. The first being anti-windup augmentation to give satisfactory performance when rate limit constraints are imposed on the actuators and the second being a strategy to account for two arrays of actuators with different dynamics. The resulting control schemes offer both stability and performance guarantees within structures that are feasible for online computation in real time.