Bioinspired antagonistic joint drives based on translatory piezo motors - construction and control approaches.

Modern piezoelectric motors like the PiezoLEGS motor (PiezoMotor Uppsala AB, Stålgatan 14, Uppsala, Sweden) combine small size, high-precision drive capabilities, intermediate forces and fast operation. Within this project, bioinspired robotic joint drives are constructed which feature an antagonistic arrangement of piezomotors. Control algorithms based on force and position measurements are developed that foster the application of superordinate neurobionic control approaches. A possible future application is the area of microgripping and microrobots.

Contact: Filip Szufnarowski

Neurobionic control concepts for elastic joint drives.

Current robotic research focuses on elastic features of joints and segments as a basis for safe human-machine interaction and cooperation. The roadmap for strategies and regulations "to let the robots out of their cages" is currently designed. We suggest to observe the biological example closely to implement already successful solutions on technical systems. This project aims at the development of new control approaches which integrate muscle models and bioinspired controllers in a technical framework with a strong foundation in classical control theory. These approaches will be used for different types of motors which incorporate real as well as simulated elastic elements. Experiments, simulations and theoretical considerations will be used to compare bioinspired and classical approaches to finally use the best combinations of solutions from these two worlds.

Contact: Salvatore Annunziata

Development of integrated, miniaturized, elastic actuators based on synchronous motors.

The development of lightweight and small-sized joint drives for robotic application is the centre point of this project. These joint drives contain all necessary electronics to host bionics control ideas together with classical robot controllers. A key feature of these novel actuators will be the power-to-weight ratio which lies in the range of real, biological muscles (nominal operation). Ongoing optimization minimizes the amount and weight of (non-functional) housing parts. As found in biological examples, the drives in this project feature a high integration level of micro sensors. At the end stands a bioinspired, self-contained and modular drive system that can be used for different limb constructions.

Contact: Jan Paskarbeit and Salvatore Annunziata

Designing a multi-legged robot as a test-bed for motion intelligence mechanisms.

In the last years, work in different projects established an understanding of walking on a basic level. However, biological research demands a different perspective on the construction and control of walking, running and climbing agents which in many cases does not fit into the framework roboticists are used to. In the presented project, a compliant and powerful walking/climbing machine is developed. The control of the legs and their coordination is based on biological findings. The local control approaches are tightly connected to the idea of embodiment and situatedness. The leg coordination - in the shape of neural networks - is the foundation for planning-capabilities as one key feature of cognition.

Contact: Jan Paskarbeit

A four-phase arbitrary waveform generator for the control of translatory piezo drives.

The generation of arbitrary waveforms is solved in modern waveform generators. However, for the control of translatory piezo drives, a four-phase power system is needed which exceeds the features of current of-the-shelf waveform generation. The most important features of this power system are a) the generation of free relations between the phases (including online-mirroring), b) output of the phase system with an electric power that corresponds to the power rating of the motor and c) a small scale electronics setup w.r.t. the small-sized piezo motors. In addition, this project combines piezo motor control functions directly with waveform generation algorithms.

Contact: Daniel Basa

Design and implementation of control- and power electronics for a BLDC motor.

To apply bioinspired control approaches to joint drives which are actuated by modern, synchronous electrical motors, a close interaction between hardware controllers and neurobionical control layers is important. This interaction must be facilitated by integration of both aspects on just one electronic setup. This project investigates the principle layout of a combination of miniaturized power electronics and microcontroller-based control electronics. Different small-sized electronic setups were first designed and then investigated to minimize noise and cross-talk effects. A key feature of miniaturization of power electronics is the ability to operate the power system with small-sized capacitors. This aspect was also taken into consideration.

Contact: Jeffrey Queißer and Jan Paskarbeit

Active measurement of the substrate stiffness in multi-legged standing.

Recent biological studies on stick insects suggest that the character of the joint controllers (I-, P- or D-controller) depends on the compliance of the substrate (soft, intermediate or inelastic) the insect is standing on. To model these results, we proposed a self-adjusting joint controller that changes its own setpoint in dependance of the substrate stiffness. The substrate stiffness is determined by means of a correlator circuit that compares movement commands injected into the joint with the actual responses of the leg. In addition, this project investigates if the correlation approach described above can also be used when several legs of one body perform the stiffness test at the same time.

Contact: Dr. Axel Schneider
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