Thesis (B.A.Hons. 1978) from the Department of History, University of Adelaide.

München, Techn. University, Diss., 2004.

Compass orientation or menotaxis is defined as the ability to orient at a specific angle relative to a directional cue. Cues used for compass orientation include the sun, stars, moon, geomagnetic field and polarized light. While there is evidence in a variety of organisms for compass orientation, the ability of mammals to use cues for compass orientation has been relatively unexplored. The goal of this research was to explore whether laboratory mice could use either magnetic or auditory cues for compass orientation. The results indicate that mice are able to learn to position their nest using a magnetic compass. The development of a magnetic compass assay in laboratory mice will allow the investigation of the mechanism of magnetic compass orientation in mammals, a goal that has been unattainable to this point.In addition, this research has provided preliminary evidence that mice are able to learn to position their nests using an auditory compass. While there is evidence in several organisms for place navigation using auditory cues (i.e. the ability to locate a specific spatial position using auditory cues), this is the first evidence in any organism for an auditory compass (i.e. the ability to calculate a directional heading relative to an auditory cue).In conclusion, both experiments provide evidence for specialized compass systems in mice and suggest that further research is necessary to fully understand the role of these systems in the behavioral ecology of mice. / Master of Science

The use of a standalone Global Navigation Satellite System (GNSS) has proved to be insufficient when navigating indoors or in urban canyons due to multipath or obstruction. Recent technological advances in low cost micro-electro-mechanical system (MEMS) – based sensors (like accelerometers, gyroscopes and magnetometers) enabled the development of sensor-based navigation systems. Although MEMS sensors are low-cost, lightweight, small size, and have low-power consumption, they have complex error characteristics. Accurate computation of the heading angle (azimuth) is one of the most important aspects of any navigation system. It can be computed either by gyroscopes or magnetometers. Gyroscopes are inertial sensors that can provide the angular rate from which the heading can be calculated, however, their outputs drift with time. Moreover, the accumulated errors due to mathematical integration, performed to obtain the heading angle, lead to large heading errors. On the other hand, magnetometers do not suffer from drift and the calculation of heading does not suffer from error accumulation. They can provide an absolute heading from the magnetic north by sensing the earth’s magnetic field. However, magnetometer readings are usually affected by magnetic fields, other than the earth magnetic field, and by other error sources; therefore magnetometer calibration is required to use magnetometer as a reliable source of heading in navigation applications. In this thesis, a framework for fast magnetometer calibration is proposed. This framework requires little space coverage with no user involvement in the calibration process, and does not need specific movements to be performed. The proposed techniques are capable of performing both 2-dimensional (2D) and 3-dimensional (3D) calibration for magnetometers. They are developed to consider different scenarios suitable for different applications, and can benefit from natural device movements. Some applications involve tethering the magnetometers to the moving platform (like in cars and machinery applications). Other applications are related to portable navigation (smartphone navigation, whether for pedestrians or while driving). The developed framework was examined through experimental work to verify its performance and robustness. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-05-01 00:52:30.274

Universiẗat, Diss., 2003--München.

Universiẗat, Diss., 2002--Bonn.

This study addresses the discrepancy between the range of Beethoven's double bass parts and the instrument or instruments in use in Vienna in his day. Scholars and musicians have complained about Beethoven's apparent disregard for the instrument's capabilities since the middle of the nineteenth century. A systematic examination of Beethoven's orchestral writing for the double bass shows that this reputation is undeserved. In fact Beethoven paid close attention to the lower compass of the double bass throughout his orchestral writing: a clear boundary of F is observed up to op. 55, and thereafter E, though F still obtains in some late works. Beethoven's observance of the F boundary suggests that he was writing for the Viennese five-stringed violone, and not the modern form of the instrument, as has previously been assumed in scholarship. Other evidence pointing to the use of this instrument is presented. Some of Beethoven's bass parts between op. 55 and op. 125 do in fact descend to C (sounding C1); yet there is no evidence supporting the existence of a double bass instrument capable of C1 in Beethoven's day. Possible explanations for these violations of the compass of the double bass are discussed. These focus on the possibility of simple proofreading error, and on evidence for the unwritten practice of reinforcing the double bass with one or more contrabassoons. The contrabassoon in Beethoven's day had a lower compass of C1, and Vienna was an early center for its production and use. Analysis of the bulk of Beethoven's double bass parts for their range is given. Emphasis in this analysis is given to instances where Beethoven demonstrates a clear awareness of the compass of the instrument. Out-of-range pitches are compiled in table form.

A fiber optic system for measuring magnetic heading and pitch of one or more compass heads in a towed acoustic array has been developed as a cooperative effort between engineers at Fiber Dynamics, Inc., and faculty and graduate students at Texas A&M. An unconventional photolithographic process for producing a bar-code pattern on a curved (spherical) surface was successfully implemented. First, an absorption process for applying a thin layer of photoresist uniformly to the gold-coated surface of a glass sphere was perfected. Then, a system for defining the patterns in the metal was assembled. A LabView computer program controlled the system as required to define the bar code pattern in the metal. High-quality bar code patterns were produced on floating spheres by this method. The data acquisition/signal processing system digitized and processed the raw data returning from the compass heads, and computed magnetic heading and pitch from the data. Processing of the signal from a single compass head required readout of a 7-bit binary code giving coarse heading, using timing information to obtain fine heading, and measuring the apparent width of an analog bar to determine pitch. When monitoring multiple compass heads distributed along the fiber, a time-division demultiplexing technique was used for separating the data from the individual compass heads. For testing the system, the cylindrical sensor head was mounted on a machinist's table for rotating it through 360?? in the horizontal plane to vary the heading, and through ??10?? about a horizontal axis to vary pitch. Measured resolutions of the system were 0.044?? for heading, and 0.85?? for pitch.

Techn. University, Diss., 2004--München.

At an early age, i.e., up to about 1-2 years, humans learn to walk and subsequently develop a robust and flexible gait. This is learned by repetitively taking similar steps and the experience is stored in the muscle/reflexive memory. Over the last 30 years, a variety of humanoid bipedal robots have been developed to copy the human gait. However, walking/locomotion is still a relatively difficult control problem due to its complex hybrid nature because of non-smooth dynamics. Although, simple walking comprises of single support in which one leg swings forward, then it impacts with ground for a brief double support phase and further transition of the other support leg to start a new swing. The steps are repeated again and again in a similar manner for walking over an even surface. As the swinging leg strikes the ground, it is a non-linear impact which poses a challenge since it causes non-zero initial state errors for each step which depend on the error in the gait at last moment for previous step. The usual bipedal control relies on complex techniques based on inverse kinematics, ZMP (Zero-Moment Pole) and COP (Centre Of Pressure) to generate the required control inputs for the joints. However, a basic cognitive assumption is that walking is a relatively simple task which can be learned and the biological systems have achieved it by simple repetitions. This has been over-looked in these control techniques. In the past, ILC has been proposed to solve the repetitive learning problems. The Iterative Learning Controller learns to generate the desired set of input signals to compensate for the output tracking errors in a sequential manner such that in the initial iterations, the signals values at earlier time indices have faster rate than the later ones. So, at the last time index the convergence is achieved after all the earlier ones. ILC learns/adapts the joint control for repetitive gaits. In this thesis it has been proposed to be used as a muscle memory where control signals are learnt for a repetitive batch. Thus, ILC equates to “learning a sequence of action by muscles”. Due to the transfer of state error in a cyclic manner from the end of a previous step/repetition to the recent step/repetition, the convergence has to be established in joint control and state space. Similar is the case of continuous walking where the ground impacts transfer part of the error in the gait to the start of a new step representing an impacting Cyclic ILC scenario. Hence, the ILC problem is changed from finite to an infinite horizon. The second problem occurs with the non-constant length of the iteration due to change in step size. The two scenarios have been considered: Firstly, when the control input is updated using ILC with identical initial conditions at the start of each repetition. Secondly, control input update under varying initial conditions leading to Cyclic ILC. The batch to batch evolution of control inputs at each sample time within a batch is formulated. The sequential convergence of control input generated by ILC algorithms has been investigated. The exact relationship for the rate of convergence of the control input has been formulated down to the sample-time level. This provides deeper insight about the ILC algorithms and hence exact factors affecting the convergence could be established. Limits of the learning process have been clearly demonstrated as well. Although, simpler D-ILC converges for zero initial error but for cyclic non-zero initial errors, it has offset error which corresponds to the initial state error. With proportional part, the PD-ILC algorithm has eliminated the offset error which has been illustrated for a damped pendulum and further implemented to bipedal locomotion. For reasons of energy efficiency, passive dynamics has been chosen for the compass gait model of the biped. The walking problem for the compass gait robot has been solved using the modified PD-ILC which utilizes the acceleration error term as well. The steady gait has been achieved for the compass gait robot on flat surface which has been verified by the phase portraits.