Tobias Hesse

Shape Memory Alloy in Tension and Compression and its Application as Clamping-Force Actuator in a Bolted Joint: Part 1 — Experimentation

In recent years, there have been some endeavors in order to characterize and model Shape Memory Alloy (SMA) behavior both in tension and compression. However, the one-dimensional behavior of SMA has been mostly studied for the case of wire elements subjected to tension. The objective of this paper is to analyze the behavior of Ni-55.7% wt Ti SMA in tension, compression, and at various temperatures. The effects of cycling, annealing, and friction on the mechanical behavior of this material in compression are discussed as well and, where applicable, compared to those of tension. The compressed SMA rings are finally used as clamping-force actuators in loosed bolted joints. In the second part of this paper, the experimental findings are compared with the theoretical counterparts.

An Approach to Integrate Vehicle Dynamics in Motion Planning for Advanced Driver Assistance Systems

Path planning procedures belong to the key software elements for advanced driver assistance systems including vehicle following, lane-keeping, lane-changing, or collision avoidance. One approach to realize an integrated driver assistance on the guidance level is based on an elastic band immersed in a potential field hazard map. This paper presents an extension of this elastic band path planning method, incorporating the vehicle dynamics in the elastic band. It is shown that this measure enhances the drivability of the planned paths.

Path-Planning with Virtual Beams

This paper presents a novel path-planning approach as for example for future driver assistance systems. The method is based on a virtual beam that is deflected under the influence of a potential field hazard map. The method is predictive, avoids local minima, and has its strengths in the continuous model and the controllability of the paths curvature.

Motion planning for passenger vehicles - force field trajectory optimization for automated driving

Trajectory planning is one of the key software modules to enable the development of advanced driver assistance sys tems or autonomously driving cars to further enhance traf fic safety. This paper presents a novel coupled trajectory planning approach for autonomous driving along a road. It uses a two-step algorithm to achieve integrated planning of path and velocity profile to best create feasible, collision free trajectories through dynamic traffic environments. The first step, the trajectory initialization, uses an A* based search in a combined search space that consists partly of command space and state space, to efficiently plan a tra jectory specifying position, velocity and time. The local search algorithm used for trajectory optimization is based on trajectory deforming force fields. It operates on a low dimensional search space in , , , but employs a depen dent higher dimensional space to account for the dynamic quantities of the motion model, (velocities, accelerations, jerk), as well as the extrapolated movements of obstacles. The approach is able to handle arbitrary road curvatures. The trajectory planning approach has been implemented and demonstrated in an autonomous test vehicle. First ex perimental results are shown and discussed.

Comparison of the Experimental Behavior of a Shape Memory Alloy in Compression and Tension

The concept of Shape Memory Alloy (SMA) has been a subject of extensive research in the recent few years. In many SMA applications, wire elements have been used in order to control structural specifications like shape and stiffness. Since a wire can only be subjected to tensile forces, the available theoretical models for DMA discuss only the tensile loading. The present paper is an endeavor to overcome this shortcoming. It gives experimental resluts for tension and compression tests on specimens (having different geometries) made of an identical shape memory alloy. The corresponding results are compared with each other. Using stress-strain diagrams, several important material properties are obtained. These parameters can then be implemented in SMA models in order to analyze and predict the mechanical behavior of SMA elements subjected to compression.© 2003 ASME

CONCEPT OF AN ACTIVE FRONT-LIGHTING DRIVER ASSISTANCE SYSTEM

Abstract This paper presents the general idea and structure of an active front-lighting system that creates an optimal adaptive light distribution that prevents the glaring of other road users and marks hazard potentials. The concept represents a mechatronic system consisting of sensors, actuator, information processing, and a mechanical basic structure. In addition to the functional structure and basic organization of the information processing, hardware considerations for the implementation of the sensor and actuator side are shown.