Jonas Fredriksson

Tangible user interface for chemistry education: comparative evaluation and re-design

Augmented Chemistry (AC) is an application that utilizes a tangible user interface (TUI) for organic chemistry education. The empirical evaluation described in this paper compares learning effectiveness and user acceptance of AC versus the more traditional ball-and-stick model (BSM). Learning effectiveness results were almost the same for both learning environments. User preference and rankings, using NASA-TLX and SUMI, showed more differences and it was therefore decided to focus mainly on improving these aspects in a re-design of the AC system. For enhanced interaction, keyboard-free system configuration, and internal/external database (DB) access, a graphical user interface (GUI) has been incorporated into the TUI. Three-dimensional (3D) rendering has also been improved using shadows and related effects, thereby enhancing depth perception. The re-designed AC system was then compared to the old system by means of a small qualitative user study. This user study showed an improvement in subjective opinions a out the systems ease of use and ease of learning.

Nonlinear control applied to gearshifting in automated manual transmissions

In this paper the problem of automating the gearshift process of a manual transmission without synchronizers is investigated. The application is very interesting from an integrated powertrain control point of view, since it includes many different control tasks and encourages the use of the engine as an actuator to the rest of the powertrain. A model-based control law for the task of gearshifting is presented. The controller is designed based on the backstepping methodology. It includes control laws for transmission torque control as well as for engine speed control. Simulations have shown good results for the gearshift controller.

Wheel force distribution for improved handling in a hybrid electric vehicle using nonlinear control

In this paper a vehicle motion controller is presented. The idea is to use generalized forces acting on the center of gravity of the vehicle and then use a control allocation-like method to distribute the generalized forces to wheel forces. The controller is designed based on feedback linearization of a simple vehicle model. The performance of the controller is evaluated by simulations on a more complex vehicle model. The proposed controller can handle the new flexibility introduced by new powertrain configurations, this is shown by using the same controller on two different vehicle configurations.

Powertrain Control for Active Damping of Driveline Oscillations

When a vehicle is subjected to acceleration or disturbances, the elasticity of the various components in the driveline may cause torsional vibrations which can result in an oscillating vehicle speed. These driveline oscillations are also known as shuffle and are low frequency oscillations corresponding to the first resonance frequency of the driveline. The oscillations give rise to, apart from material stress, noticeable lessened driveability. In this work, different ways to actively damp the oscillations are investigated. The idea is to use the engine as an actuator in order to achieve active damping, so-called active engine control. Different linear controllers are investigated and evaluated. The paper includes driveline modelling, control design and verifications by simulations, and tests in real vehicle. Implementation issues such as limited amount of available engine torque and parameter identifications are also discussed. A Linear-Quadratic-Gaussion (LQG) controller has been implemented and tested on a heavy duty truck. Results show that the LQG controller works well and active damping is achieved.

Cylinder-by-Cylinder Engine Models Vs Mean Value Engine Models for use in Powertrain Control Applications

An investigation of the need of engine model complexity for use in powertrain control applications is presented in this paper. The engine studied is an SI-engine, but the analysis methods could easily be adapted to a CI-engine. The different engine models investigated are a cylinder-by-cylinder engine model and a mean value engine model. The way to evaluate the engine models is to compare the dynamical behavior and how the engine affects the driveline. The analysis is made by studying the engine in the frequency and time domain. The investigation shows that the mean value engine model is sufficient for use in powertrain simulations and for powertrain control design. The dynamical behavior for the two models coincide, and the combustion pulses are well damped in the driveline (powertrain without engine). A less complex structure is preferable when designing a control system. However, to study the effects of backlash it can not be concluded which degree of engine model complexity to use, since it depends on the time spent in the backlash as well as the control strategy.

A receding horizon approach to string stable cooperative adaptive cruise control

A time domain approach to a “string stable”, i.e., capable of attenuating acceleration shockwaves, cooperative adaptive cruise control is proposed in this paper. A receding horizon scheme is adopted to design a controller which attenuates acceleration shockwaves generated by the preceding vehicle while avoiding rear-end collisions. The classical definition of string stability in frequency domain is revised in the time domain and a new criterion for predecessor-follower string stability based on the acceleration signals is defined and used. Simulation and experimental results are presented to show the effectiveness of the proposed method.

Real-time 3D hand-computer interaction: optimization and complexity reduction

This paper presents a low-cost method for enabling 3D hand-computer interaction. The method, accompanied by a system, uses the frame capturing functionality of a single consumer-grade webcam. Our recent work has been focused on examining and realizing a less complex system. The presented method reduces the tracking effort to only one reference marker: a color-coded bracelet that helps locate the part of the captured frame containing the users hand. The located area contains all the information needed to extract hand rotation and finger angle data. To facilitate hand feature extraction, we have outfitted the users hand with a specially coded glove. The glove is equipped with two square palm markers, a marker on either side of the hand, and five distinctly shaded finger sheaths. We believe that an approach that only tracks only one marker will be more efficient than similar methods that track each finger separately. The method is further simplified by using spatial properties, drawn from physiological characteristics of the human hand, to limit the areas considered by the algorithm. Some challenges regarding webcam limitations may arise when attempting to carry this method into effect, including problems related to image noise and limited image- and color-resolution. Overlapping hands and fingers, hand positioning outside the field of view, and interference by local light sources are other exigent factors to consider.

A methodology and a tool for evaluating hybrid electric powertrain configurations

This paper describes a methodology for automatic optimisation of hybrid electric powertrains. This methodology is developed and implemented in a tool, CAPSimO, and the paper is written in the form of describing the tool. Given the user inputs, which are dynamic vehicle model, driving cycle and optimisation criterion, the tool first produces a simplified powertrain model in a form of static maps, before dynamic programming is used to find an optimal power split which minimises the chosen criterion. The tool does not require that the vehicle model is transparent, which makes it possible to work on models hidden for intellectual property reasons. The paper presents two examples of powertrain evaluation, in terms of fuel consumption, for a parallel and a parallel-series powertrain.

Estimating exhaust manifold pressure in a turbocharged diesel engine

The problem of estimating the exhaust manifold pressure in a turbocharged diesel engine is considered. The reciprocated engine causes the air-flow in the exhaust manifold to oscillate with a frequency that is a multiple of the engine speed. As a result of the oscillating airflow the pressure in the exhaust manifold will also oscillate. This oscillation makes it difficult and expensive to measure the pressure. Instead an observer for the exhaust manifold pressure is proposed. The observer is model-based, and the performance of the observer is evaluated by simulations.

Lane Change Maneuvers for Automated Vehicles

By considering a lane change maneuver as primarily a longitudinal motion planning problem, this paper presents a lane change maneuver algorithm with a pragmatic approach to determine an inter-vehicle traffic gap and time instance to perform the maneuver. The proposed approach selects an appropriate inter-vehicle traffic gap and time instance to perform the lane change maneuver by simply estimating whether there might exist a longitudinal trajectory that allows the automated vehicle to safely perform the maneuver. The lane change maneuver algorithm then proceeds to solve two loosely coupled convex quadratic programs to obtain the longitudinal trajectory to position the automated vehicle in the selected inter-vehicle traffic gap at the desired time instance and the corresponding lateral trajectory. Simulation results demonstrate the capability of the proposed approach to select an appropriate inter-vehicle traffic gap and time instance to initialize the lateral motion of a lane change maneuver in various traffic scenarios. The real-time ability of the lane change maneuver algorithm to generate safe and smooth trajectories is shown by experimental results of a Volvo V60 performing automated lane change maneuvers on a test track.