David Inkermann

Passive and Adaptive Joints for Parallel Robots

In order to take advantage of parallel kinematic structures, the development of specific and optimized structure components (rods, passive joints) is becoming increasingly necessary. Accordingly, in this chapter the development and implementation of novel joint concepts for parallel structures is discussed. The focus lies on two different joint types: firstly, conventional passive joints and secondly, adaptive joints with integrated piezo-actuators. Based on the specific design methodology, different joint prototypes are developed and tested. By drawing on the test results, it is shown how the novel joints influence performance of the whole robot system.

Adaptronic couplers — An alternative drive principle

Complex mechatronic systems with a number of independently driven elements generally employ an equal number of drive elements. Commonly, these systems are actuated by electric motors and hence electric energy is transmitted through them. In various systems, however, mechanical energy may be distributed through the system instead of electrical energy and may be used directly to drive output elements. Using electric servo motors and servo drives, highly dynamic torque, velocity, and position control of output elements can be achieved easily. However, there is no machine component that can transmit a variable torque from an input shaft to an output element and enable highly dynamic torque, velocity, and position control of the output element. Adaptronic couplers are novel machine components which can close this gap. This paper introduces the concept of adaptronic couplers and addresses potential applications in mechatronics/robotics. Various experimental results allow a preliminary evaluation of the viability of the approach as well as a discussion of constructional and control issues still to be addressed.

Dynamic Reconfiguration of Parallel Mechanisms

Shorter product life cycle as well as higher product complexity and diversity require more flexible manufacturing systems. Dynamic reconfiguration is a time efficient way to adapt system properties to rapidly changing process requirements. The potential to reconfigure parallel mechanisms depends on specific and optimized machine components, which enable modification of kinematic behaviour of the system. In this contribution influence of several component parameters on system properties and the needs to develop more suitable machine components are highlighted. Furthermore, a possibility to adapt kinematic properties of a planar RRRRR-mechanism, using an adaptive revolute joint, is introduced.

A FRAMEWORK FOR THE APPLICATION OF ADAPTRONIC SOLUTION PRINCIPLES

There is an increasing need for products that are able to react to changing operating conditions and user demands to achieve a high level of performance. Adaptronic solutions allow for property adjustments without major effects on system weight and size when they are applied in early phases of the design process. Since a framework for the design of adaptronic solutions is not yet established, this paper introduces an initial procedure and principles to provide design knowledge. The paper first gives an overview on adaptronics and adaptability as well as principles and guidelines for designing adaptable products. Fifteen adaptronic solution principles are derived from adaptronic solutions to provide the information needed for the design of adaptable products. A framework is proposed to apply the introduced principles within the conceptual design phase to avoid design conflicts and undesired effects. Finally, the framework is used for the design of adaptive joints for robotic applications.Copyright

Redundancy resolution and control of manipulators driven by antagonistic pneumatic muscles

Pneumatic artificial muscles feature lightweight and compact construction, in combination with high obtainable forces and an intrinsic compliance. This makes them well suited for the actuation of kinematically redundant manipulators, but due to the limited deflection of the single muscles and the highly nonlinear static and dynamic characteristics, a whole new set of challenges arises. In this contribution, redundancy resolution and control strategies are presented, which take the main actuator non-linearities into account to make effective use of the advantages provided by the pneumatic muscle actuators. The presented approach is demonstrated on a manipulator consisting of modular segments each actuated by a pair of antagonistic pneumatic muscle actuators. The approach proves to allow the avoidance of the pressure- and deflection-dependent joint limits to ensure a maximum of controllability of the manipulator at each point in the workspace.

Integrated Product Gestalt Design Method for the Analysis and Definition of Interface Elements Regarding Exterior and Interior

The exterior and interior of products are often considered as independent systems in the development process. But both the interior and the exterior gestalt are of great relevance for the usage and perception of a product. As a consequence of technological advance, such as increased automation, the borders between exterior and interior are becoming blurred. The Integrated Product Gestalt Design Definition proposed in this paper facilitates the consideration of the interrelations between and resulting complexity of different aspects of a gestalt integrating exterior and interior. We therefore distinguish between the subgestalts layout, shape, colour with surface and graphics to describe both the exterior and interior. The interdependencies between interior and exterior are characterized by functional-technical and aesthetical aspects. To derive essential relations between the exterior and interior view different products, covering investment goods and consumer goods, are analyzed. This analysis reveals the most common relations between the exterior and interior systems and allows for finding recurring patterns of relations between exterior, inner space and interior. This is a prerequisite for the predictive quality of the Integrated Product Gestalt Design. Thus, the approach facilitates the next step of a guided implementation of a method for the development process by highlighting the links between the disciplines.

Representing the Effects of Product Architecture for Decision-Making in Conceptual Design

The definition of the product architecture has a great impact on customer satisfaction, company strategy, and costs. Whereas these effects mostly become visible in later stages of the product development, most decisions on the product architecture are made early in conceptual design when allocations of functions to solution elements are determined. To support these decisions, many methodical approaches exist, for instance, for functional integration or modularization. However, a big part of those merely addresses single effects of the product architecture. This paper presents a comprehensive approach to draw correlations between targets derived from the specific development task and methods for product architecture design. Therefore, it contributes towards the structuring of existing methods in order to enable the designer to select most suitable methods for specific development tasks.

Design for Pedestrian Protection

Pedestrians are among the most vulnerable participants in current city traffic. While in the past original equipment manufacturers (OEMs, in meanings of carmakers) mainly focused on passenger safety, nowadays strict legislation requirements call for the development of more effective pedestrian safety concepts. Considerations for constructive and technological road safety measures generally take place in a company-specific product development process, but mainly in phases, that do not allow for innovative products in terms of new solutions. Thus, the importance of early development phases as well as design process models, such as Pahl and Beitz, will be described here. Also the significance of the development design cases will be handled, as they can mainly influence the innovation degree of the resulting products. In the end an approach will be introduced, of how an analysis of product models regarding their possibilities for adequate evaluation can help, to support a safety-related development process by integrating suitable design methods and tools.Copyright

Adaptronic Solution Principles: Potential to Flexible Design

This contribution introduces the concept of adaptronic solution principles (Alp) to support the development of products for changing requirements. Based on an approved understanding of flexible products, three aspects are proposed to characterize Alp. Since adaptronic systems are object of current research, a set of solutions is analyzed concerning the aspects design flexibility, product flexibility and realization concept. This analysis points out major characteristics of Alp and their potential to close conflicting requirements and affect product properties within the use phase automatically. Finally, the introduced Alp are applied for the development of an adaptronic coupler within a new drive concept for serial kinematic manipulators.

Joint actuation based on highly dynamic torque transmission elements - concept and control approaches

Electric motors clearly constitute the most common drive principle in robotics and mechatronics. Smart materials, however, offer considerably higher power-to-mass ratios than electric motors. If mechanical energy instead of electrical energy can be distributed through a system, highly dynamic and efficient torque transmission elements based on smart materials, e.g. piezoceramics, can be used to transmit torque from an input to an output element. Just like electric motors, they can thus provide position, velocity, and force-torque control of the output element. This paper introduces machine components, called adaptronic couplers, which can transmit variable torques highly dynamically from an input element to an output element employing static and/or dynamic friction. In the long run, systems (e.g. robots) based on these machine components are envisaged to compete with systems based on classic drive principles - especially electric motors - w.r.t. dynamics and power-to-mass-ratio. Apart from the concept itself, this paper addresses different control approaches and discusses their influence on energy consumption and wear. Moreover, various experimental results proving the basic concept are presented.