Towards a prototype of a spherical tippe top

Among spinning objects, the tippe top exhibits one of the most bizarre and counterintuitive behaviours. The commercially available tippe tops basically consist of a section of a sphere with a rod. After spinning on its rounded body, the top flips over and continues spinning on the stem. It is the friction with the bottom surface and the position of the center of mass below the centre of curvature that cause the tippe top to rise its centre of mass while continuing rotating around its symmetry axis (through the stem). The commonly used simplified mathematical model for the tippe top is a sphere whose mass distribution is axially but not spherically symmetric, spinning on a flat surface subject to a small friction force that is due to sliding. Adopting a bifurcation theory point of view we reach a global geometric understanding of the phase diagram of this dynamical system. According to the eccentricity of the sphere and the Jellet invariant (which includes information on the initial angular velocity) three main different dynamical behaviours are distinguished: tipping, non-tipping, hanging (i.e. the top rises but converges to an intermediate state instead of rising all the way to the vertical state). Subclasses according to the stability of relative equilibria can further be distinguished. Since our concern is the degree of confidence in the mathematical model predictions, we applied 3D-printing and rapid prototyping to manufacture a ’3-in-1 toy’ that could catch the three main characteristics defining the three main groups in the classification of spherical tippe tops as mentioned above. This ’toy’ is suitable to validate the mathematical model qualitatively and quantitatively

Systems overview of Ono: a DIY reproducible open source social robot

One of the major obstacles in the study of HRI (human-robot interaction) with social robots is the lack of multiple identical robots that allow testing with large user groups. Often, the price of these robots prohibits using more than a handful. A lot of the commercial robots do not possess all the necessary features to perform specific HRI experiments and due to the closed nature of the platform, large modifications are nearly impossible. While open source social robots do exist, they often use high-end components and expensive manufacturing techniques, making them unsuitable for easy reproduction. To address this problem, a new social robotics platform, named Ono, was developed. The design is based on the DIY mindset of the maker movement, using off-the-shelf components and more accessible rapid prototyping and manufacturing techniques. The modular structure of the robot makes it easy to adapt to the needs of the experiment and by embracing the open source mentality, the robot can be easily reproduced or further developed by a community of users. The low cost, open nature and DIY friendliness of the robot make it an ideal candidate for HRI studies that require a large user group

Overview of technologies for building robots in the classroom

This paper aims to give an overview of technologies that can be used to implement robotics within an educational context. We discuss complete robotics systems as well as projects that implement only certain elements of a robotics system, such as electronics, hardware, or software. We believe that Maker Movement and DIY trends offers many new opportunities for teaching and feel that they will become much more prominent in the future. Products and projects discussed in this paper are: Mindstorms, Vex, Arduino, Dwengo, Raspberry Pi, MakeBlock, OpenBeam, BitBeam, Scratch, Blockly and ArduBlock

Quasi-periodic stability of normally resonant tori

We study quasi-periodic tori under a normal-internal resonance, possibly with multiple eigenvalues. Two non-degeneracy conditions play a role. The first of these generalizes invertibility of the Floquet matrix and prevents drift of the lower dimensional torus. The second condition involves a Kolmogorov-like variation of the internal frequencies and simultaneously versality of the Floquet matrix unfolding. We focus on the reversible setting, but our results carry over to the Hamiltonian and dissipative contexts

Building ArtBots to attract students into STEM learning

There is an increasing worldwide demand for people educated into science and technology. Unfortunately, girls and underprivileged students are often underrepresented in Science, Technology, Engineering and Mathematics (STEM) education programs. We believe that by inclusion of art in these programs, educational activities might become more attractive to a broader audience. In this work we present an example of such an educational activity: an international robotics and art week for secondary school students. This educational activity builds up on the project-based and inquiry learning framework. This article is intended as a brief manual to help others organise such an activity. It also gives insights in how we led a highly heterogeneous group of students into learning STEM and becoming science and technology ambassadors for their peers

An empirical analysis of potential cyclist injuries and cycling outfit comfort

This study investigated the relationship between pain/injury and training characteristics in cyclists. In addition, ergonomic wear comfort of their garments was investigated. A total of 94 complete questionnaire responses were analyzed. The result indicated that lower back pain was the most prevalent injury causing the highest rates of functional damage and medical attention. The injury level of cyclists was affected by the cluster with elite cyclists reporting pain while cycling. Many cyclists were not very satisfied with the comfort level of their current outfit, 39% of respondents were experienced with different discomfort sensations. The most frequent causes of discomfort were thermal and moisture discomfort sensation related to fabric characteristics. Moreover, design and fit of the garment were considered as cause of discomfort next to thermal discomfort sensation. Therefore, it could be concluded that garments that have good ventilation or breathability and very good fit values were preferred by cyclists. Design, limited choice (availability), appearance/look and quality were the main reason for their brand selection preferences