<p>The Ericsson R380 is a so-called smartphone, combining an advanced mobile phone with a Personal Digital Assistant (PDA). To evaluate the usability of the Ericsson R380 and benchmark it against the Nokia 9110 Communicator and the Motorola A6188 Accompli, a repeated measurements experiment was performed. 18 subjects (10 men and 8 women) with no previous experience of any of the interfaces participated. Half of the subjects had extensive experience from using Ericsson mobile phones and half of the subjects had extensive experience from using Nokia mobile phones. A set of 9 tasks to be solved on each interface was presented to the subjects. The order in which the subjects used the interfaces was balanced with a Latin square design while the tasks were presented in consecutive order and were identical for all interfaces. Level of completeness, completion time and number of actions were assessed for each task and interface. Subjects also rated the perceived usability and aesthetics of the interfaces. Overall, subjects were most successful using the Motorola A6188 Accompli, using fewer keystrokes and less time as well as needing fewer hints compared to the Ericsson R380 and Nokia 9110 Communicator. However, the Ericsson R380 was rated significantly higher than the other interfaces on perceived usability. Previous experience with Ericsson or Nokia mobile phones did not have a major impact on how well subjects succeeded with using the interfaces in the test. Certain mistakes made by each group of subjects could be explained in terms of mental models, Einstellung effects and the use of so- called Function-Object interaction style where Object-Function interaction was appropriate. Contrary to earlier findings, aesthetics and perceived usability did not correspond to a great extent. Finally, the results are discussed and some suggestions for improvements are put forward.</p>

To navigate successfully in a previously unexplored environment, a mobile robot must be able to estimate the spatial relationships of the objects of interest accurately. A Simultaneous Localization and Mapping (SLAM) sys- tem employs its sensors to build incrementally a map of its surroundings and to localize itself in the map simultaneously. The aim of this research project is to develop a SLAM system suitable for self propelled household lawnmowers. The proposed bearing-only SLAM system requires only an omnidirec- tional camera and some inexpensive landmarks. The main advantage of an omnidirectional camera is the panoramic view of all the landmarks in the scene. Placing landmarks in a lawn field to define the working domain is much easier and more flexible than installing the perimeter wire required by existing autonomous lawnmowers. The common approach of existing bearing-only SLAM methods relies on a motion model for predicting the robot’s pose and a sensor model for updating the pose. In the motion model, the error on the estimates of object positions is cumulated due mainly to the wheel slippage. Quantifying accu- rately the uncertainty of object positions is a fundamental requirement. In bearing-only SLAM, the Probability Density Function (PDF) of landmark position should be uniform along the observed bearing. Existing methods that approximate the PDF with a Gaussian estimation do not satisfy this uniformity requirement. This thesis introduces both geometric and proba- bilistic methods to address the above problems. The main novel contribu- tions of this thesis are: 1. A bearing-only SLAM method not requiring odometry. The proposed method relies solely on the sensor model (landmark bearings only) without relying on the motion model (odometry). The uncertainty of the estimated landmark positions depends on the vision error only, instead of the combination of both odometry and vision errors. 2. The transformation of the spatial uncertainty of objects. This thesis introduces a novel method for translating the spatial un- certainty of objects estimated from a moving frame attached to the robot into the global frame attached to the static landmarks in the environment. 3. The characterization of an improved PDF for representing landmark position in bearing-only SLAM. The proposed PDF is expressed in polar coordinates, and the marginal probability on range is constrained to be uniform. Compared to the PDF estimated from a mixture of Gaussians, the PDF developed here has far fewer parameters and can be easily adopted in a probabilistic framework, such as a particle filtering system. The main advantages of our proposed bearing-only SLAM system are its lower production cost and flexibility of use. The proposed system can be adopted in other domestic robots as well, such as vacuum cleaners or robotic toys when terrain is essentially 2D.

The Ericsson R380 is a so-called smartphone, combining an advanced mobile phone with a Personal Digital Assistant (PDA). To evaluate the usability of the Ericsson R380 and benchmark it against the Nokia 9110 Communicator and the Motorola A6188 Accompli, a repeated measurements experiment was performed. 18 subjects (10 men and 8 women) with no previous experience of any of the interfaces participated. Half of the subjects had extensive experience from using Ericsson mobile phones and half of the subjects had extensive experience from using Nokia mobile phones. A set of 9 tasks to be solved on each interface was presented to the subjects. The order in which the subjects used the interfaces was balanced with a Latin square design while the tasks were presented in consecutive order and were identical for all interfaces. Level of completeness, completion time and number of actions were assessed for each task and interface. Subjects also rated the perceived usability and aesthetics of the interfaces. Overall, subjects were most successful using the Motorola A6188 Accompli, using fewer keystrokes and less time as well as needing fewer hints compared to the Ericsson R380 and Nokia 9110 Communicator. However, the Ericsson R380 was rated significantly higher than the other interfaces on perceived usability. Previous experience with Ericsson or Nokia mobile phones did not have a major impact on how well subjects succeeded with using the interfaces in the test. Certain mistakes made by each group of subjects could be explained in terms of mental models, Einstellung effects and the use of so- called Function-Object interaction style where Object-Function interaction was appropriate. Contrary to earlier findings, aesthetics and perceived usability did not correspond to a great extent. Finally, the results are discussed and some suggestions for improvements are put forward.