The transport layer is the essential part in the open system interconnection (OSI) reference model, since it is the interface between the software-oriented layers 5-7 and hardware-oriented layers 1-3. On the one hand, it provides a general approach for data exchange with the software-oriented layers, independent of the underlying hardware. On the other hand, it is responsible for an efficient and reliable use of the underlying hardware. These characteristics make the transport layer crucial for the effective usage of a communication system, as it significantly reduces the implementation effort for the software-oriented layers.The lack of a transport layer is a huge disadvantage. Combining the functionality of different communication layers into single application specific protocols can lead to the coexistence of multiple, non compatible approaches, resulting in a higher implementation effort for integrating new applications. Therefore, the existence of a transport layer is fundamental for both communication software and hardware, to provide established communication concepts, which are a precondition for the use of standardized software libraries, and to integrate modern computing trends (e.g. Big Data, Data-Mining, machine learning, cyber security).SpaceWire does not yet define a general transport layer. This paper presents the approach of a minimalist SpaceWire transport layer, as common base for the implementation of higher level protocols. It comprises both the hardware related SpaceWire transport node and the associated software counterpart as well as the associated protocol. The transport layer implementation is one result of our longstanding SpaceWire development and is already in use in several robotic systems.

In the recent years the two main disciplines of space robotics have been exploration e.g. ill as well as service and maintenance e.g. Pl. Depending on the application, the system level complexity differs significantly. Both disciplines comprise on the one hand dedicated robots for a very specific task (e.g. [3, 41) and on the other hand highly complex systems (e.g. [5, 61) with different levels of autonomy. However, independent of the complexity, all robotic systems can be described as a configuration of joints. Therefore, a joint can be considered as the smallest unit of a robot's configuration to setup a specific kinematic structure. We applied this joint based module approach for mechanic, electronics and software development already in several terrestrial robotic developments e.g. [7,8] who even reached commercialization state. Hence the logical step was to apply this approach also to space robot development of CAESAR (Compliant Assistance and Exploration SpAce Robot) [91). In this paper we focus on the electronics and software part by presenting the computation and communication architecture for a universal space robotic joint based on CAESAR's joint control unit (JCU). It comprises all aspects from the overlying high level control of multiple joints on a real-time host down to the synchronisation of communication participants on register transfer level (rtl). This involves also the used middleware implementation and fieldbus communication as well as actuator control and sensor data acquisition.

Dexterity and strength are essential for performing a variety of tasks in the unstructured environments of household services and craftsmanship. For these tasks, we have developed neoDavid, a robust humanoid robot with dexterous manipulation skills. neoDavid has joints with variable-stiffness actuators (VSAs), which have mechanically adjustable elasticity in the drive train, a continuum elastic neck, and a gravitationally compensated torso with overload couplings. We present our modular approach in the development, starting from system architecture over mechatronic components, communication, and control to higher-level software. We demonstrate how this modularity enables scalable enhancements, allowing us to evolve the system from a single arm and hand into a complete humanoid robot. Additionally, we highlight advancements in perception, manipulation, and motion planning, along with the implementation of offline task planning utilizing capability maps. The versatile character in terms of dexterity and robustness is demonstrated in challenging applications, e.g., handling a drill hammer, fine manipulation of a pipette, and emptying a dishwasher.

In this work we present the modularity aspect in the development of neoDavid, a robust humanoid robot with dexterous manipulation skills. We highlight the benefits of modularity in humanoid robot design for flexible service robotic applications. Our modular approach to system development begins with the system architecture and extends through the mechatronics, connectivity, and control components to the higher-level software and applications that match the growing system architecture. We show how the modularity scales and how it was used to gradually expand the system from an arm and hand to a full humanoid upper body on wheels. The modularity allowed us to adapt our system to changing needs as our focus shifted from technology basics to skills and finally to applications in the human environment with human tools.

Wheeled rovers have been successfully used as mobile landers on Mars and Moon and more such missions are in the planning. For the Martian Moon eXploration (MMX) mission of the Japan Aerospace Exploration Agency (JAXA), such a wheeled rover will be used on the Marsian Moon Phobos. This is the first rover that will be used under such low gravity, called milli-g, which imposes many challenges to the design of the locomotion subsystem (LSS). The LSS is used for unfolding, standing up, driving, aligning and lowering the rover on Phobos. It is a entirely new developed highly-integrated mechatronic system that is specifically designed for Phobos. Since the Phase A concept of the LSS, which was presented two years ago [1], a lot of testing, optimization and design improvements have been done. Following the tight mission schedule, the LSS qualification and flight models (QM and FM) assembly has started in Summer 2021. In this work, the final FM design is presented together with selected test and optimization results that led to the final state. More specifically, advances in the mechanics, electronics, thermal, sensor, firmware and software design are presented. The LSS QM and FM will undergo a comprehensive qualification and acceptance testing campaign, respectively, in the first half of 2022 before the FM will be integrated into the rover.

Upcoming space missions, like the Mars Sample Return Mission, increasingly aim to include robots to enable highly skilled tasks and to increase safety. However, the requirements for such robots are high, due to the demanding environment and the high reliability of the system needed to operate independently in space. As part of the ESA project for a Sample Transfer Arm (STA) breadboard study, the German Aerospace Center (DLR) has developed a small modular torque controlled robotic manipulator that complies with the MSR mission requirements. It has 7 degrees of freedom (DOFs) and a total arm length of 2,30 m. The brakes hold the arm in position during no operation and serve as emergency stop. The reachability of the robot was investigated in a workspace study. Each robotic joint incorporates a brushless high torque DC motor combined with a harmonic drive gear stage and a planetary pre-gear stage. A Universal Motor Controller (UMC) is placed in each shoulder of the robotic arm, which consists of an FPGA, phase current measurement, the motor bridge driver and peripherals. To ensure safety and flexibility, a redundant matrix concept is integrated in the UMC, which allows control of more than one joint in case of a failure. The communication between the joints and the OBC (On-board-computer) is using SpaceWire with a 3 kHz cycle time, implemented in the joints FPGA. The motor control loop and the joint torque controller are implemented in the FPGA. The joint power is fed by two separate supplies, logic and motor, for a greater efficiency in power limited missions. The torque estimation analysis proved that the maximum required torques can be generated in each joint. To ensure the absolute high accuracy of the arm position sensing, the motors have a hall-sensor twelve step commutation and in addition a resolver on the link side resolver. An internal torque sensor in each joint is added to measure torques on the end-effector which allows collision avoidance during a task. To allow autonomous tasks, such as moving samples from a rover and inserting them into a sample container, various intelligence features have been included. For the arm control, a RCU (Robot Control Unit) is located in the base of the arm, implementing a Cartesian impedance and position controller. With all these features, the newly developed robotic manipulator meets all the needed requirements of the MSR mission. It is capable of interacting with sensitive spacecraft components, but can also be used as a payload manipulator for rovers.

Purpose of Review Robotic assistance systems for diagnosis and therapy have become technically mature and widely available. Thus, they play an increasingly important role in patient care. This paper provides an overview of the general concepts of robotically assisted surgical systems, briefly revisiting historical and current developments in the surgical robotics market and discussing current focus areas of research. Comprehensiveness cannot be achieved in this format, but besides the general overview, references to further readings and more comprehensive reviews with regard to particular aspects are given. Therefore, the work at hand is considered as an introductory paper into the topic and especially addresses investigators, researchers, medical device manufacturers, and clinicians, who are new to this field. Recent Findings The current research in Robotically Assisted Surgical Systems (RASS) increasingly uses established robotic platforms. To minimize the patient trauma while optimizing the dexterity of the surgeon, miniaturized instruments and semi-autonomous assistance functions are developed. To provide the surgeon with all necessary information in an adequate manner, novel imaging sensors as well as techniques for multimodal sensory feedback and augmented reality are investigated. The Surgical Data Science applies data management and processing approaches including machine learning on medical data to provide optimal, individualized and contextual support to the surgeon. Summary Robotic systems will significantly influence future patient care. Since they must fulfill manifold medical, technical, regulatory and economic requirements, their development calls for a close, active and interdisciplinary cooperation between stakeholders from hospitals, industry and science.

This paper gives an overview of the control and computing architectures of current lightweight robots and their demands on on board data processing units. On Earth, robots are an established technology in our daily life. They are getting more and more aware of their surroundings, which allows their use in many new domains. Collaborative workplaces where a robotic co-worker directly interacts with a human are already state of the art. Current research on machine learning and Artificial Intelligence (AI) in the robotic domain will introduce many new applications for robotic systems. These developments also have a great potential to be used in future space missions, for example on-orbit servicing of satellites or maintenance of space stations. However, this induces certain requirements on involved computing hardware that future on-board data processing units will also have to deal with.

Using a pressurized waterjet for cutting or abrasing tissue is a well established method in surgery. This paper presents a robotic tool for minimally invasive waterjet surgery with two degrees of freedom, integrated suction and an optional splash protection. The function of the tool and the effect of the splash protection on the suction of the applicated water was successfully evaluated in tests with ballistic gelatine. Based on this evaluated design, a concept for further increasing the oscillation frequency of the instrument tip is introduced and the results of preliminary tests of a simplified mockup are shown.

To enhance the capability of the DLR MIRO for physical human robot interaction (pHRI), six buttons were integrated as additional input interface along the robot structure. A ring of eight RGB-LEDs at the instrument interface informs the user as additional output interface about the robot’s state. The mechatronic design, which is transferable to other robots, adapts to the existing communication infrastructure of the robot and therefore offers real-time capability. Besides the interaction with the robot itself, it also allows the control of third party devices connected to its communication network. Both interfaces can be flexibly programmed e.g. in C++ or Simulink.

SpaceWire has been used successfully as commu- nication backbone implemented on Field Programmable Gate Arrays (FPGAs) in several robotic systems at the DLR. However, the growing number of available System-on-Chip (SoC) solutions with integrated programmable logic and the demand for efficient processing power in embedded systems require high speed On- Chip communication. Using SpaceWire as interconnection bus inside FPGAs has a major drawback compared to dedicated On-Chip bus systems. As it is not designed to exploit the wide parallelism of FPGAs, several On-Chip communication standards outperform SpaceWire in terms of bandwidth and resource costs. Examples are the AMBA AXI bus, the Avalon bus, CoreConnect or the Wishbone SoC Interconnection. In this work, the Wishbone standard is used to show, how an FPGA system connected to a SpaceWire network can benefit from a dedicated On-Chip bus. The architecture of the Wishbone standard allows an almost seamless integration into a SpaceWire network. Essential parts of SpaceWire, like package oriented communication or time- code distribution, can be mapped onto the Wishbone standard. A slim protocol is presented to allow accessing the On-Chip address space from the SpaceWire network and vice versa. It is also shown, that a heterogeneous On-Chip network consisting of SpaceWire and Wishbone occupies less resources on an FPGA than a similar network implemented with SpaceWire only. In the future, this approach can be used to integrate SoCs with built-in programmable logic into a SpaceWire network.

This chapter gives a brief overview of the DLR MiroSurge versatile surgical robotic demonstrator, its major components, mechatronic design and control paradigms. Central component is the robot arm Miro based on intelligent mechatronic technology developed at DLR. The system is adapted to various medical applications by attaching various instruments, e.g., the dedicated instrument MICA, and a surgeon workstation providing HD 3D vision and haptic feedback. Furthermore, a selection of current research topics concerning novel MIRS applications and system components are introduced.

OBJECTIVE:We evaluated the clinical potential of a novel robotic system for autonomous performance of waterjet wound debridement. SUMMARY BACKGROUND DATA:Within the last decade, waterjet wound debridement has proven to be a valid alternative to the conventional approach using sharp spoons and scalpel. METHODS:The DLR MIRO robot using the DLR MICA instrument for robotic surgery was adapted for actuation of an ERBEJET 2 flexible endoscopic waterjet probe. Waterjet debridement of various wound shapes and sizes using a porcine skin model was compared between this novel robotic system and a control group of human medical professionals with regard to wound area cleaned by the waterjet, off-target area, and procedural time. RESULTS:After the wound area was registered in the robotic system, it automatically generated a cleaning path and performed debridement based on generated surface model. While the robotic system demonstrated a significant advantage for the covered wound area (p = 0.031), the average off-target area was not significantly different from human controls. Human participants had high variability in cleaning quality across users and trials, while the robotic system provided stable results. Overall procedural time was significantly lower in trials performed by humans. CONCLUSIONS:Robotic waterjet wound debridement is a promising new technological approach compared to the current clinical standard of interventional wound therapy, providing higher efficiency and quality of wound cleaning compared to human performance. Additional trials on more complicated wound shapes and in vivo tissue are necessary to more thoroughly evaluate the clinical potential of this technology.

In a control application all sensors and actuators have to be able to perform their functions in a specific time to guarantee the desired control cycle. To achieve an exact actual system state a synchronization of the different sensor measurements is necessary. This guarantees that all acquired values are in a very small period of time and not spread over the whole control cycle. Otherwise, a noiser system state would result. The simplest way to synchronize those measurements is with cyclic triggering. This can be either an external request via communication or generated locally by a timer. Both approaches work well in a monolithic system approach with a central unit due to the existence of a common clock domain. However, a distributed system consists of multiple monolithic systems connected via communication, each with a separate clock domain. Due to the communication delay from unit to unit, and the differences between the local clocks, a synchronization according to the presented approaches is only possible by introducing a global clock domain. With time-codes SpaceWire already includes a mechanism to distribute time over a network. However, the communication delay regarding the time-code distribution is not considered. In systems consisting of large networks which have to be synchronized in very small cycles (e.g. high dynamic robots see [1]) this aspect is not negligible. This approach introduces a global time distribution by synchronization and runtime compensation. The synchronization is based on digital phase locked loops (PLLs) which align the units’ local time to the occurence of SpaceWire time-codes. The runtime compensation of the time- code distribution in the network is based on statistical evaluation.

In waterjet surgery, a thin high-pressure jet is used for dissections and surface abrasion of soft tissue. This selective preparation method preserves nerves and vessels, whereas the surrounding soft tissue is washed away. Objective: The aim of this study is to enhance the application field of this technique by resolving technological limitations. Methods: A technical task definition of handling a hand-guided waterjet applicator is derived from the literature. All reported procedures require to follow a trajectory superimposed with an oscillating movement. By introducing a robotic system and a specialized kinematic approach, the limited dexterity of the waterjet applicator is increased. Additionally, the system provides assistance by automatically performing parts of the task. Results: The method is applied to two different procedures: a minimally invasive dissection and a surface abrasion for open medical treatments. On the basis of experiments with gelatine phantoms, the performance of the method is shown for both procedures. Conclusion: In the minimally invasive use case, the reachability limited by the conventional manual tools is extended by the capabilities of the robotic system. Simultaneously, the handling is simplified by automation of the superimposed oscillation. In the surface abrasion case, a dense coverage of the treated area is achievable. The risk of cross infections could be reduced by spatial separation of patient and staff. Significance: Thus, the waterjet technology can be fully integrated into robotic surgery systems and benefit from their inherent abilities.

Complex robotic systems like the DLR Hand Arm System integrates a huge amount of sensors and actuators. Hence system design and especially communication infrastructure design has to be flexible in a heterogeneous network of different bus systems. As basis, a modular electronic concept as well as a well-structured communication concept is necessary [1]-[3]. SpaceWire suites well to these requirements since on one hand it supports arbitrary topologies from point to point up complex network structures and on the other hand it is easy to implement and has a small footprint. Additionally its logical and regional addressing scheme enables changes in the topology during runtime simply by reprogramming the routing switches. However, such changes require expert knowledge. This work presents a graphical method to setup and configure SpaceWire network topologies. This enables non-experts to replace or integrate new components to the system or to set up a test bed to investigate a specific aspect. The developer provides a GraphML description [4] specifying the SpaceWire communication capabilities of each component. Thus the user is able to adapt the SpaceWire network topology or to set up a new one simply by merging the different GraphML descriptions of the used components. A post process is afterwards used to analyze the GraphML description and to generate the necessary configuration messages according to the topology. This enables faster development cycles and rapid prototyping. The approach is approved and explained using the SpaceWire network topology of the DLR Hand Arm System. Index Terms— Graphical Communication

Complex robotic systems like the DLR Hand Arm System integrates a huge amount of sensors and actuators. Hence system design and especially communication infrastructure design has to be flexible in a heterogeneous network of different bus systems. As basis, a modular electronic concept as well as a well-structured communication concept is necessary [1]-[3]. SpaceWire suites well to these requirements since on one hand it supports arbitrary topologies from point to point up complex network structures and on the other hand it is easy to implement and has a small footprint. Additionally its logical and regional addressing scheme enables changes in the topology during runtime simply by reprogramming the routing switches. However, such changes require expert knowledge. This work presents a graphical method to setup and configure SpaceWire network topologies. This enables non-experts to replace or integrate new components to the system or to set up a test bed to investigate a specific aspect. The developer provides a GraphML description [4] specifying the SpaceWire communication capabilities of each component. Thus the user is able to adapt the SpaceWire network topology or to set up a new one simply by merging the different GraphML descriptions of the used components. A post process is afterwards used to analyze the GraphML description and to generate the necessary configuration messages according to the topology. This enables faster development cycles and rapid prototyping. The approach is approved and explained using the SpaceWire network topology of the DLR Hand Arm System.

Robots that are not only robust, dynamic, and gentle in the human robot interaction, but are also able to perform precise and repeatable movements, need accurate dynamics modeling and a high-performance closed-loop control. As a technological basis we propose robots with intrinsically compliant joints, a stiff link structure, and a soft shell. The flexible joints are driven by Variable Stiffness Actuators (VSA) with a mechanical spring coupling between the motor and the actuator output and the ability to change the mechanical stiffness of the spring coupling. Several model based and model free control approaches have been developed for this technology, e.g. Cartesian stiffness control, optimal control, reactions, reflexes, and cyclic motion control.