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A. Albu‐Schäffer, S. Haddadin, Ch. Ott, A. Stemmer, T. Wimböck and G. Hirzinger
The paper seeks to present a new generation of torque‐controlled light‐weight robots (LWR) developed at the Institute of Robotics and Mechatronics of the German Aerospace Center.
Abstract
Purpose
The paper seeks to present a new generation of torque‐controlled light‐weight robots (LWR) developed at the Institute of Robotics and Mechatronics of the German Aerospace Center.
Design/methodology/approach
An integrated mechatronic design approach for LWR is presented. Owing to the partially unknown properties of the environment, robustness of planning and control with respect to environmental variations is crucial. Robustness is achieved in this context through sensor redundancy and passivity‐based control. In the DLR root concept, joint torque sensing plays a central role.
Findings
In order to act in unstructured environments and interact with humans, the robots have design features and control/software functionalities which distinguish them from classical robots, such as: load‐to‐weight ratio of 1:1, torque sensing in the joints, active vibration damping, sensitive collision detection, compliant control on joint and Cartesian level.
Practical implications
The DLR robots are excellent research platforms for experimentation of advanced robotics algorithms. Space and medical robotics are further areas for which these robots were designed and hopefully will be applied within the next years. Potential industrial application fields are the fast automatic assembly as well as manufacturing activities done in cooperation with humans (industrial robot assistant). The described functionalities are of course highly relevant also for the potentially huge market of service robotics. The LWR technology was transferred to KUKA Roboter GmbH, which will bring the first arms on the market in the near future.
Originality/value
This paper introduces a new type of LWR with torque sensing in each joint and describes a consistent approach for using these sensors for manipulation in human environments. To the best of one's knowledge, the first systematic experimental evaluation of possible injuries during robot‐human crashes using standardized testing facilities is presented.
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Heng Liu, Wei Su and Fu‐tang Zhang
This paper aims to provide detailed information on the dynamic model and closed‐loop control theory for a resonant accelerometer based on electrostatic stiffness, which is…
Abstract
Purpose
This paper aims to provide detailed information on the dynamic model and closed‐loop control theory for a resonant accelerometer based on electrostatic stiffness, which is important for the design of this type of resonant accelerometer.
Design/methodology/approach
After analysing the principles of the resonant accelerometer based on electrostatic stiffness, a dynamic model was built. According to the requirements of the closed‐loop control, the control equations based on phase‐locked technology were also built for the system. With the help of the averaging method, the system behaviour was analysed, and the equilibrium for the vibration amplitude was achieved.
Findings
The theoretical analysis and simulation show that integral gain is critical to system stability. When it is larger than the critical point, the system stable time is shorter, but the frequency‐tracking process fluctuates; if it is smaller than the critical point, the system stable time is longer, and the frequency‐tracking process stabilizes a resonant accelerometer was fabricated with a bulk‐silicon‐dissolved process. With the above conclusions, the accelerometer was driven and tested with a sensitivity of 47 Hz/g for a single vibration beam.
Originality/value
The dynamic model and the control theory for the resonant accelerometer based on electrostatic stiffness were presented in this paper. The simulation and experiment results agree well with the theoretical analysis.
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M. Görner, T. Wimböck and G. Hirzinger
The purpose of this paper is to present and evaluate methods of control and gait generation for the DLR Crawler – a six‐legged walking robot prototype based on the fingers of the…
Abstract
Purpose
The purpose of this paper is to present and evaluate methods of control and gait generation for the DLR Crawler – a six‐legged walking robot prototype based on the fingers of the DLR Hand II.
Design/methodology/approach
Following the institutes philosophy, the DLR Crawler is a highly integrated mechatronic device. As in all DLR robots, joint torque sensing plays an important role to allow actively compliant interaction with the environment. To control the Crawler a joint compliance controller is implemented and two different methods of gait generation are in use. The first method, intended for moderately uneven terrain, employs scalable patterns of fixed coordination combined with a leg extension reflex. For the second method, used in rougher terrain, a set of rules found by biologists in stick insect studies is applied. Based on these rules gaits emerge according to a velocity command. These gaits are combined with several reflexes to a reactive walking algorithm.
Findings
The compliance controller together with the reactive gaits allows the robot to autonomously master uneven terrain and obstacles with height differences within the nominal walking height. Further, the controller reduces internal forces compared to pure joint position control. The sensitive joint torque sensors allow fast collision detection and reactions thereafter.
Originality/value
This paper introduces a six‐legged walking robot test bed with comprehensive force‐torque sensing capability. Joint compliance controllers are implemented and successfully combined with reactive gait algorithms. For the second gait algorithm inspired by Cruse's rules, which were identified for forward walking stick insects, an implementation has been found for the DLR Crawler that gives the robot full omnidirectional mobility.
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Adha Imam Cahyadi and Yoshio Yamamoto
The purpose of this paper is to present a design and verification through experiments of teleoperation of the 3 degrees‐of‐freedom micromanipulation system (MMS), in laboratory…
Abstract
Purpose
The purpose of this paper is to present a design and verification through experiments of teleoperation of the 3 degrees‐of‐freedom micromanipulation system (MMS), in laboratory conditions.
Design/methodology/approach
The MMS is constructed from piezoelectric actuators sited in a flexure hinge mechanism. The nonlinearity, especially hysteresis, due to a voltage steering scheme is compensated for, via a second‐order Dahl friction model. A simple mechanical model is then constructed to capture the behavior of the MMS. Redundant force feedback sensors are applied to the MMS in order to achieve flexible operation via the so‐called fault‐tolerancing mechanism. Finally, a teleoperation scheme based on passivity formalism is proposed to achieve a stable teleoperation system.
Findings
The hysteresis curve due to voltage steering can be minimized. The fault‐tolerancing concept using redundant sensors for comfortable use of the MMS has been successfully performed. The teleoperated MMS via a commercially available PHANToM® has been conducted under ineligible telecommunication channel delay.
Originality/value
The details of design, modelling and experimentations of the teleoperation of the MMS should promote the applicability of similar systems in the future.
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Presents an on‐line calibration methodology for robot relative positioning inaccuracy. This methodology eliminates the need for time‐consuming off‐line calibrations relying on…
Abstract
Presents an on‐line calibration methodology for robot relative positioning inaccuracy. This methodology eliminates the need for time‐consuming off‐line calibrations relying on accurate models and complicated procedures. To realize this methodology, a vision system, a 3D force/torque sensor, and control strategies involving Neural Networks (NNs) were incorporated with an industrial robot.
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This paper aims to provide details of recent commercial and academic developments in flexible and soft grippers and considers their impact on emerging robotic markets.
Abstract
Purpose
This paper aims to provide details of recent commercial and academic developments in flexible and soft grippers and considers their impact on emerging robotic markets.
Design/methodology/approach
Following an introduction, this paper first considers commercially available anthropomorphic robotic hands and soft grippers. It then discusses a selection of recent research activities and concludes with a brief discussion of the potential of these developments.
Findings
Anthropomorphic robotic hands, which seek to mimic the structure and capabilities of the human hand, together with a technologically diverse family of soft grippers have recently have been commercialised. Most are produced by companies which spun-out from academic establishments. A strong body of innovative research continues and involves a wide range of principles and technologies. These gripping technologies are expected to catalyse several new and emerging applications; the most important being in agile manufacturing, particularly when used with collaborative robots (cobots).
Originality/value
This paper provides details of recent developments and research into anthropomorphic hands and soft grippers and an insight into their applications.
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Mark Lowe, Alison King, Elizabeth Lovett and Thomas Papakostas
The continued evolution of computer technology requires us now more than ever to investigate and understand man‐machine interfaces. Physical interface peripherals such as…
Abstract
The continued evolution of computer technology requires us now more than ever to investigate and understand man‐machine interfaces. Physical interface peripherals such as touch‐screens and force feedback systems demand a comprehension of the tactile forces involved. To accomplish this, flexible, easy‐to‐install, minimally intrusive sensors are essential. Thanks to the development of such sensors, many doors have been opened for innovative haptic applications in a variety of fields including medicine, manufacturing, and entertainment.
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At a time when there is a seeming influx of imports the US is turning increasingly to the exploitation of its advanced technology and manufacturing research. One key area is that…
Abstract
At a time when there is a seeming influx of imports the US is turning increasingly to the exploitation of its advanced technology and manufacturing research. One key area is that of sensor research which is likely to have major implications.
Novel nanomaterials and nano-devices require further functional aspects that can be designed and supported using new nanomanipulation techniques allowing specific functions at the…
Abstract
Purpose
Novel nanomaterials and nano-devices require further functional aspects that can be designed and supported using new nanomanipulation techniques allowing specific functions at the design phase. The nano-manipulator becomes a key instrument for technology bridging sub-nano to mesoscale. The integration of various operations in nano-devices requires sub-nanometer precision and highly stable manipulator. This paper aims to review various design concepts of recent nanomanipulators, their motion characteristics, basic functions, imagine and automation with control techniques for the sake of establishing new design features based on recent requirements.
Design/methodology/approach
The paper reviews various existing nanomanipulators, their motion characteristics, basic functions, imagine and automation with control techniques. This will support precision machine design methodology and robotics principles.
Findings
The availability of a nano-precision instrument with integrated functions has proved to be extremely helpful in addressing various fundamental problems in science and engineering such as exploring, understanding, modeling and testing nano-machining process; exact construction of nano-structure arrays; and inspection of devices with complex features.
Originality/value
New functional specifications have emerged from this review to support the design and make of new advanced nanomanipulators with more features availability to support manipulation within the same reference datum needed for research and education.
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