Videos of Selected Research Topics

Ball-Catching with a Redundant Industrial Robot

For exhibition purposes, the demonstrator needs to be able to catch balls which are thrown into its workspace by the audience. In our approach the demonstrator's manipulator is composed of a six-axes industrial robot, mounted onto a rapidly moving linear axis, resulting in a redundant robotic system. To track the thrown ball, a highly sophisticated and also actuated vision system is used. From a mechatronical (and also industrial) perspective, various interesting challenges arise in the process of modeling and control of the overall system.


Omnidirectional Mobile Robot

Traditional mobile platforms (like car's) are mostly built on a four-wheeled base with two steerable wheels. This type of platform limits the feasible motions. Moving sideways and turning around are problematical maneuvers for conventional mobile platforms. The construction of special kinds of wheels (Mecanum wheels), which enable the platform to move in any desired direction (omnidirectional), is a suitable solution to resolve these disadvantages. The concept of this platform differs from existing rectangular-shaped ones by a novel, octagonal base-form construction. The kinematic properties of the platform are not limited due to this way of construction at all. On contrary it is possible to achieve remarkable benefits in combination with the robot operating system ROS (autonomous navigation).


Online Walking Gait Generation with Predefined Variable Height of the Center of Mass

For biped robots one main issue is the generation of stable trajectories for the center of mass (CoM). Several different approaches based on the zero moment point (ZMP) scheme have been presented in the past. Due to the complex dynamic structure of bipedal robots, most of the considered algorithms use a simplified time invariant linear model to approximate the dynamics of the system. This model is extended to a time variant one and then used to generate stable CoM trajectories with variable predefined CoM height. This allows to generate trajectories online for walking underneath obstacles with more accuracy. It is shown that using this extended scheme it is possible to overcome some kinematic limits as joint speed in the knee or the maximum step length for common walking.  


Time-Optimal Path Planning of an Articulated Robot

The increasing industrial requirements in the wide field of robotics demand steadily increasing performance. The clip begins with a standard trajectory with constant velocity, the common way to program the robot's toolpath. Then, by using model based optimization strategies, the cycle time is drastically reduced. Depending on the application, the optimal path can be calculated for given geometric paths or by defining two arbitrary points.

Die Optimierung von Bahnen hinsichtlich der dynamischen und kinematischen Grenzen spielt eine immer größere Rolle. Online und Offline Lösungen werden am Institut für Robotik entwickelt und in diesem Video gezeigt. 


Disturbance Suppression of an Elastic Robot

This video compare the disturbance behaviour on the elastic robot ELLA with different control concepts. Using a common PD motor joint control high oscillations on the TCP are generated. In contrast by using a model based control this weakness can be compensated.

Im Vordergrund steht die Dämpfung von Schwingungen des Roboterendpunkts. Die Messung der Krümmung der Balken dient zur aktiven Regelung des Endpunkts auf Grund von externen Kräften. Dafür werden in diesem Video unterschiedliche Regelungsalgorithmen verglichen.  


Ball Catching Scenario of an Elastic Robot

In this video we will demonstrate the versatility of a lightweight structure, like the elastic robot ELLA. Due to the fact that we have only three joints and therefore not the possibility to control the orientation independently, we selected the following setup: The ball leaves the mount by moving the robot sidewards and so the ball accelerates towards the ground. Therefore, the task of the robot is to overtake and then to catch the object with the mounted hat. This process lasts 0.6sec, from the start command to the final catching, and needs approx. 1.4m in gravitational direction from the start to the end position. Please remark, that with the common PD motor joint control it is impossible to track such a fast motion on the elastic robot.

Der elastische Roboter fängt auf Grund seiner sehr hohen Beschleunigungen den von ihm selbst fallen gelassenen Ball. Die Strukturelastizitäten werden dafür mit Hilfe aktiver und passiver Schwingungsdämpfung kompensiert. Grundlage dafür liefern flachheitsbasierte Ansätze, welche als Messung das Beschleunigungssignal des Endpunkts und des Ellbogengelenks zur Verfügung haben. 


Vibration Suppression and Tracking Control of an Elastic Robot

In this video we compare a common PD motor joint control and a model based control concept at a fast straight line in space on the elastic robot ELLA. We see immediately, the PD motor joint control cannot be used for any fast application, due to the high oscillations on the TCP. Moreover there is a great improvement in terms of vibration suppression with the model based control concept.

Mit Hilfe einer Beschleunigungsrückführung werden Schwingungen am Endpunkt des elastischen Roboters unterdrückt. Diese werden mit einer klassischen PD - Regelung verglichen.



Rotor Test Bench

To validate numerical simulations of the rotordynamic model, a test bench was built. Hereby the rotor is driven by a permanent-magnet synchronous motor which is controlled by a Bernecker and Rainer system and the motor torque is transmitted with a spur gear pair. These are chosen to analyze parametric excitation based on varying tooth mesh stiffness. Also a second drive coupled via a tooth belt to the rotor can be attached.


Mehrkörpersimulation mit O(n) Verfahren

Die Dynamik einer 20 gliedrigen Kette wird mit Hilfe eines O(n) Verfahren inkl. einem Kontakt- und Stoßmodell simuliert.


Dynamische Simulation von elastischen Plattenschwingungen

Das Video enthält die dynamische Simulation von elastischen Plattenschwingungen, angeregt von einem externen Stoß in überdimensionalen Darstellung.


Hochlauf eines elastischen Antriebsstrangs

Dieses Video zeigt eine dynamische Simulation eines Anstiebsstrangs mit elastischen Körpern, Getriebestufen und Lagerung.


Schwingungskompensation Elastischer Roboter

Durch eine Korrektur der Bahn wird jede beliebige Bahn in Echtzeit in eine Bahn verwandelt, sodass keine Schwingungen am Endpunkt auftreten. Die Messung der Krümmung der Balken dient zur aktiven Regelung des Endpunkts auf Grund von externen Kräften. Diese beiden Verfahren zur Schwingungsunterdrückung werden mit der gewöhnlichen PD - Gelenksregelung verglichen.


Störunterdrückung Elastischer Roboter

Im Vordergrund steht die Dämpfung von Schwingungen des Roboterendpunkts. Die Messung der Krümmung der Balken dient zur aktiven Regelung des Endpunkts auf Grund von externen Kräften. Dafür werden in diesem Video unterschiedliche Regelungsalgorithmen verglichen.


Stepplanner for a biped robot

The video demonstrates the function of an A* based step planner for a biped robot. The planner computes an optimal sequence of footsteps from a given start location to a given end position. Possible footsteps are limited to a finite set. Static obstacles in the two dimensional map are considered so that the robot can walk through the environment without collisions.


Handguided Robot Control using Microsoft Kinect

Combining Microsoft's low-cost vision capture system "Kinect" with the realtime control of an industrial robot allows the mapping of human arm gestures to the movement of an articulated robot.

Handgeführte Robotersteuerung und Sprachsteuerung eines Industrieroboters mit Kinect.


Inner Oscillation Detection and Evaluation of Unknown Test Objects

Objectives of the experiment:
- Use a 6 DOF compliant hexapod to generate frequency sweeps in all degrees of  freedom
- get a "sensorless" detection instrument with very quick and easy results

Purpose:
- new tool for vibration tests
- quality check after production, before shipping
- lifetime test for extensive vibration during usage or shipping


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