Jan Helbo

Proceedings of the 13th Mediterranean Conference on Control and Automation

An equivalent circuit method describing the free stator of piezoelectric motor is presented in this paper, while the circuit elements have complex values. The mechanical, dielectric and piezoelectric losses associated with the vibrator are accounted for by the imaginary components of the circuit elements. It is shown that the calculation of the circuit parameters from the complex elastic, dielectric and piezoelectric material constants is straightforward and the model accuracy is verified with simulation around the important frequencies suitable for motor controller design purposes

Motion planning for humanoid robots based on virtual constraints extracted from recorded human movements

In the field of robotics there is a great interest in developing strategies and algorithms to reproduce human-like behavior. In this paper, we consider motion planning for humanoid robots based on the concept of virtual holonomic constraints. At first, recorded kinematic data of particular human motions are analyzed in order to extract consistent geometric relations among various joint angles defining the instantaneous postures. Second, a simplified human body representation leads to dynamics of an underactuated mechanical system with parameters based on anthropometric data. Motion planning for humanoid robots of similar structure can be carried out by considering solutions of reduced dynamics obtained by imposing the virtual holonomic constraints that are found in human movements. The relevance of such a reduced mathematical model in accordance with the real human motions under study is shown. Since the virtual constraints must be imposed on the robot dynamics by feedback control, the design procedure for a suitable controller is briefly discussed.

Full scale experiences with didactic changes in distance education in Master of Industrial Information Technology (MII)

This paper reports the main results of didactic changes in the first year of an experiment in ICT-based distance learning. The results are based on a full scale experiment in the education, Master of Industrial Information Technology (MII). The experiment transforming the well functioning on-campus engineering program based on project organized collaborative learning to the technology supported distance education program failed. Despite of many miner didactic changes, we did not obtain the same self regulating learning effect in the group work among the off-campus students as is the case for on-campus students. For the first time, we have deviated from the normal Aalborg University problem based learning model by separating course study and project work. The feedback from the students was very positive but we did expect that the collaboration and discussion on the Internet would increase as well. Questionnaires, discussions and measurements of the Internet activities show results which are contradictory compared to expectations.

Virtual Learning Environments and Learning forms - experiments in ICT-based learning

This paper report the main results of a three year experiment in ICT-based distance learning. The results are based on a full scale experiment in the education, Master of Industrial Information Technology (MII) and are one of many projects deeply rooted in the Project Virtual Learning Environments and Learning forms (ViLL). The experiment was to transfer a well functioning on-campus engineering program based on project organized collaborative learning to a technology supported distance education program. After three years the experiments indicate that adjustments are required in this transformation. The main problem is that we do not find the same self regulating learning effect in the group work among the off-campus students as is the case for on-campus students. Based on feedback from evaluation questionnaires and discussions with the students didactic adjustments have been made. The revised didactic model has until now been a positive experience.

AAU-BOT1: a platform for studying dynamic, life-like walking

This paper describes the development of the humanoid robot AAU-BOT1. The purpose of the robot is to investigate human-like walking and in this connection, test prosthetic limbs. AAU-BOT1 has been designed with modularity in mind making it possible to replace, e.g. the lower leg to test transfemoral or transtibial prosthesis or orthosis. Recorded motion data from a male test person, along with approximated inertial and mass properties, were used to determine necessary joint torques in human walking which was used as design parameters for the robot. The robot has 19 degrees of freedom DoF, 17 actuated and 2 unactuated acting as passive toe joints. The project was granted 60,000 Euro, and to keep development costs below this, the development and instrumentation was carried out by three groups of master students from the Department of Mechanical Engineering ME and the Department of Electronic Systems at Aalborg University and supported by the Department of Health Sciences and Technology HST. To further reduce the cost, the robot uses off-the-shelf hardware which also reduced the time from idea to practical implementation. The result is a low-cost humanoid robot fully assembled and equipped with sensors ready to take its first steps.

Comparing On-Campus and Distance Education assessment in the form of Project Organized Problem Based Learning (POPBL)

This paper describes the first experiences in on-line assessment in the POPBL distance education: Master of Industrial Information technology (Mil) at Aalborg University, Denmark (AAU). The accomplished assessment of some projects and some courses has been changed from a normal on-campus seminar activity to an on-line event. The modifications in roles for teacher, censor and student are reported and some recommendations and unsolved problems are identified.

Changes in roles and behavior of learners and teachers when going for POPBL

It is accepted world wide; that project-organized problem-based learning (POPBL) is the right method to improve learning and satisfy the customers being more innovative and creative. Shifting to POPBL in universities seems uncomplicated when it comes to changes in materials and procedures, but for the people involved, mentally, it is a very difficult change in behavior and attitudes. Organizations and staff in many universities are skeptical about POPBL concerning student competence measurement and assessments. On the personal level the teachers major apprehension is the loss of prestige, templates, and traditions. Students need to be more active in the learning process so the concern is more work. It is always difficult to make major changes in an (mature) educational institution, but shifting to POPBL collaborative learning has been proven to be a successful learning method at Aalborg University, Denmark (AAU) for more than 30 years and it has provided great satisfaction for all parties including students and customers. Although, it was difficult in the beginning and after much iteration, AAU is now the leading university in on-campus POPBL, as well as on-line POPBL. However, the ongoing development of information technology (IT), pedagogy and didactic methods requires new demands to all parties in openness, willingness, and readiness in adapting new roles and behavior. This article describes challenges and changes in roles and behavior when going for and maintaining a modern and successful POPBL environment. Based on years of POPBL development and experience - methods and recommendations will be presented to staff and students when working with the courses and projects in an on-campus, as well as on-line POPBL educational environment.

Interaction Method in Human-Robot System

Abstract Robot interaction method is studied in this paper. Task allocation between human and a robot is discussed. A four-level description of robot task is presented. Human-robot interaction scheme is carried out in a high task level. Robot-environment interaction is introduced to improve the performance of the human-robot interaction and simplify the process. Human knowledge is implemented to the robot to support the interaction. The knowledge is expressed by a fuzzy relation model. An experimental robot workcell is implemented to demonstrate the interaction method.

Interdisciplinary Construction and Implementation of a Human Sized Humanoid Robot by Master Students

With limited funding it seemed a very good idea to encourage Master Students to design and construct their own human sized biped robot. Because this task is huge and very interdisciplinary different areas of expertise were covered by students from different departments who in turn took over results from former students. In the last three years three student groups from Department of Mechanical Engineering and Electronic Systems have been working on the project. The robot AAU-BOT1 has been designed, manufactured, assembled, instrumented and walking should be possible in the near future. The Project Organized Problem Based Learning method implemented at Aalborg University is one of the reasons why supervisors give Master Students such a challenge.

Free Stator Modeling of a Traveling Wave Ultrasonic Motor

An equivalent circuit method describing the free stator of piezoelectric motor is presented in this paper, while the circuit elements have complex values. The mechanical, dielectric and piezoelectric losses associated with the vibrator are accounted for by the imaginary components of the circuit elements. It is shown that the calculation of the circuit parameters from the complex elastic, dielectric and piezoelectric material constants is straightforward and the model accuracy is verified with simulation around the important frequencies suitable for motor controller design purposes