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The Energyhub@Sea concept is one of the four research applications of the Space@Sea project funded by the EU’s Horizon 2020 research program (GA number: 774253). The focus of this paper is the evaluation of the energy demands of an energy self-sufficient maintenance platform at the location of Helgoland in the North Sea. In view of this, a standardized modular floater was developed as an offshore wind operation and maintenance base, which in the following paper is referred to as an O&M hub. The O&M hub is intended to be equipped with accommodation facilities and various renewable energy infrastructure as well as spare parts logistics, enabling the platform to perform maintenance of offshore gearless wind turbines with a capacity of up to 10 MW. To be energy self-sustaining, an energy supply system for the hub was developed and simulated at a resolution of ten minutes by means of the Top-Energy simulation software, a commercial software tool. As a basis for the simulation, an approach for the automated determination of flexible load profiles, in resolutions of up to ten minutes was developed. This load profile generator creates load profiles on the basis of environmental conditions, technical characteristics, and expected behaviors of the inhabitants. On the basis of the generated load profiles, a first layout (referred to as baseline scenario) for the different components of the energy system was evaluated and tested through simulation. In a second step, three optimization scenarios were developed and simulated with regards to the financial feasibility of the Energyhub.

This paper aims to contribute the final design of a cost-effective and energy self-sufficient offshore wind operation and maintenance (O&M) platform so called Energyhu@Sea. The Energyhub@Sea concept is one of the four applications namely living, energy hub, farming, transport and logistic of the Space@Sea project funded by EU’s Horizon 2020 research program. The energy hub concept integrates four different functions within the same space such as O&M services, accommodation facilities for service staffs, renewable energy extraction and smart storage system, and housing of spare parts. The primary energy for the entire hub is supplied from a medium sized wind turbine coupled with photovoltaic modules and the wave energy converter. A special focus is put on the development of a modular and standardized system, which can be easily adapted to different climates. Moreover, the design considers the needs of future users, and health, safety and environmental risk related issues. A final design for both the North Sea site and the Mediterranean Sea site based on a hypothetical offshore wind farm with a capacity of 100 units of 10 MW direct drive turbine is presented. The results indicate that Energyhub@Sea can be a promising solution for offshore wind parks to save time and costs required for O&M activities. This study contributes useful inputs for industries towards the implementation of an offshore onsite-based O&M platform.

The Energyhub@Sea concept is one of the four research applications of the Space@Sea project funded by EU’s Horizon 2020 research program. The focus of this paper is the development of a cost-effective and energy self-sufficient maintenance platform. In view of this, a standardized modular floater was developed as an offshore wind operation and maintenance base. Four main considerations were taken into account in this development: size, shape, type and mooring. This leads to a square 45 × 45 m barge with a height of 4 m. Flexibility and scalability of the modular system is considered so that, as the scope of the project or business grows, its functionality can expand accordingly. The O&M hub will be equipped with accommodation facilities, different renewable energy infrastructure and spare parts logistics, enabling the platform to perform maintenance of offshore gearless wind turbines with a capacity of up to 10 MW. In order to be energy self-sustaining, a smart energy storage and smart grid will be optimized based on energy demand and energy supply of the entire hub.

Floating substructures for wind turbines are commonly credited for enabling the offshore wind industry, so far focused on fixed substructures, to expand into deeper waters. As per Arent et al. (Improved offshore wind resource assessment in global climate stabilization scenarios, [4]), 77% of global offshore wind potential is located in water depths deeper than 60 m. However, floating substructures do not yet meet the market expectations with regard to LCOE. By integrating new materials as well as modularity into the design, the costs of the tension leg platform (TLP) development presented in this pater have been significantly reduced. Pre-stressed Ultra-High-Performance-Concrete (UHPC) pipes will be used for this sub-structure. The buoyancy bodies will be fabricated using concrete shell elements known from tunnel engineering. The use of casted iron for the nodes and the Transition Piece (TP) leads to further advantages regarding design and costs. All components are designed for transportability (e.g. via railway) in order to ensure a high level of flexibility within the supply chain. The structural design has been calculated to support turbines of up to 6 MW rated power and more. In October 2017, a scaled model (1:50) of the new substructure design for use with a 6 MW turbine was successfully exposed to wind and wave loads at the Ocean Engineering Tank of the Ecole Centrale de Nantes (ECN). In June 2018, a second measurement campaign was started, and in September 2018 a third campaign will be run to verify the transport & installation process. Th presentation and paper will focus on the TLP design as well as on the model fabrication and scaling. Furthermore, measurement results from the ECN test will be presented. Therefore, the presentation will introduce the measurement setup as well as the measurement types to verify the simulation model. Finally, the verification of the simulation model with the measurements will be highlighted.

For the manufacturing of complex function integrative lightweight components, the pressing process specific material behavior of thermoplastic hybrid yarn textiles plays a significant role. A fundamental knowledge of the compression and heating behavior of the textile preforms is required for an efficient development of adapted tool systems. This paper focuses on the dependency of compression behavior and thermal conductivity of the glass/ polypropylene textile on varied pressure and temperature values. To analyze the thermal conductivity, the Hot Disc method is used. In general, positive trends for increasing applied pressure and temperature values on the thermal conductivity are obtained.

Floating wind turbine systems will play an important role for a sustainable energy supply in the future. The dynamic behavior of such systems is governed by strong couplings of aerodynamic, structural mechanic and hydrodynamic effects. To examine these effects scaled tank tests are an inevitable part of the design process of floating wind turbine systems. Normally Froude scaling is used in tank tests. However, using Froude scaling also for the wind turbine rotor will lead to wrong aerodynamic loads compared to the full-scale turbine. Therefore the paper provides a detailed description of designing a modified scaled rotor blade mitigating this problem. Thereby a focus is set on preserving the tip speed ratio of the full scale turbine, keeping the thrust force behavior of the full scale rotor also in model scale and additionally maintaining the power coefficient between full scale and model scale. This is achieved by completely redesigning the original blade using a different airfoil. All steps of this redesign process are explained using the example of the generic DOWEC 6MW wind turbine. Calculations of aerodynamic coefficients are done with the software tools XFoil and AirfoilPrep and the resulting thrust and power coefficients are obtained by running several simulations with the software AeroDyn.

Multi-Material Design has been identified to be an important enabler for lightweight structures, especially with regards to the goals for the large-scale implementation of e-mobility concepts. A novel 3D-Hybrid technology has been developed to combine the advantages of metal and fibre-reinforced thermoplastics in one structural part. This leads to significant weight reduction in combination with an increase in functionality. Additionally, the amount of single parts can be reduced; these factors combined make the technology competitive with conventional steel-sheet design. Investigations on basic profiles showed the feasibility of the technology in single stage production processes and proved the superior performance of the structure compared to conventional design. Finally, a B-pillar demonstration structure was produced in a highly automated process and investigated in side-impact related component tests.

A crucial problem regarding the offshore electricity generation is the levelized costs of energy (LCOE). This is an even larger problem for floating substructures for offshore wind turbines. This paper highlights a substructure for floating offshore wind turbines (FOWT) for a one step installation process. It deals with the parametric study of the TLP’s structure to gain hydrostatic and hydrodynamic stability during the transport and installation process of the TLP equipped with a 6 MW wind turbine. At first a hydrostatic analysis with the software tool MOSES (V.7.06.062) has been performed. Hydrodynamic simulations with ANSYS AQWA (V.17.2), based on 2D potential flow theory, have been conducted afterwards to get information about the motion behavior of the TLP in wind, current and waves.Copyright © 2017 by ASME

The offshore wind resources globally present a great opportunity for green power generation. Both types, fixed and floating foundations, will play a major role in utilizing these resources. The preliminary design of the floating system called GICON®-Tension Leg Platform (TLP) is meant to provide a solution for harnessing the power of offshore wind at water depths between 20 m and 350 m. In addition a design for water depth up to 700 m is currently under development. The research project is a joint development of private industry and academic institutions. The main partners are ESG GmbH and Technische Universitat Freiberg. Currently ongoing research includes the comparison of calculated data with experimental data obtained by wave tank experiments with a scale model at the Maritime Research Institute Netherlands (MARIN) in June 2013. These tests have provided insights regarding the dynamic characteristics of the GICON®-TLP by analyzing the system's response to different load cases. Furthermore, the results of the scale model tests at MARIN have confirmed that a superposition of the internal forces for wind and wave loads can be assumed for the structural design. This can be traced back to the stiffness of the mooring line system and the innovative mooring line configuration.

One important goal of the activities in the Collaborative Research Centre (SFB 639) is to obtain a scientific understanding of open technological questions for the processing of textile-thermoplastic composites. The variety of novel thermoplastic hybrid yarn textiles, like knitted and woven spacer fabrics as well as sewed spacer preforms, requires individually adapted process technologies. Therefore, a special mold system with integrated consolidation kinematics was designed which allows short cycle times in combination with a material adapted process. For the molding of different sandwich cross section contours a modular kinematic construction kit was developed. An automated assembly and demolding process necessitates a defined alignment of the kinematic components to each other using an adapted handling system. Especially the manufacturing of single curved sandwich structures requires innovative solutions which facilitate the orientation of the consolidation tools with a slight drive effort. In this paper a special focus is on the development of a novel comb system based on a scissor mechanism with reduced number of parts.

For the design of crash resistant structures for automotive applications, mainly metallic materials are currently considered. However, the advanced specific energy absorption capacity and a high lightweight potential qualifies fiber and textile reinforced thermoplastic composites for such components. With a load adapted material design as well as an efficient manufacturing concept these properties can be exploited to a full extend. A seat pan is chosen as an exemplary structure to illustrate the four main aspects of the investigations: evaluation of glass fiber polypropylene composite configurations; development of a manufacturing and process chain; crash and impact experiments on structural level and numerical modelling strategy. Hybrid yarn based textiles, such as a commercially available 2/2-twill fabric and novel multi-layered flat bed weft-knitted fabrics have been considered to be combined with a long-fibre reinforced thermoplastic material (LFT, cutting length of 25 mm) for complexly loaded sections like ribbings. A special emphasis is set on a similar to mass-production manufacturing process. A fully automated integral hot pressing process has been developed, where an automated handling system places the conglomerate of extruded LFT-material and preheated hybrid yarn textile in a fast-stroke press, achieving process cycles of 45 s. Finally, the structural evaluation under crash loading conditions is compared against numerical results.

This paper will give a short overview of the path of development of the so called GICON® - Tension Leg Platform (TLP) for offshore wind turbines. The main part of the paper will provide a summary as well as insights from three different model basin tests. Furthermore, the comparison of a truss like structure (first concept) with a shell type structure (third concept) deduced from the measured results and also by comparison of the natural frequencies will be presented. Both structures were tested in wave tanks in a scale of 1:25. The results also include a focus on the overall dynamic behavior of the structure. In addition to the two 1:25 models, a 1:37 model was also tested at MARIN, utilizing the MARIN stock wind turbine. This model is also included in the comparison. Therefore the different scales are considered but the comparison is presented exclusively for wave loads as only the 1:37 model was tested under wind and wave conditions.Copyright © 2015 by ASME

Fifteen patients with varus gonarthrosis underwent high tibial osteotomy and internal fixation with an L-shaped rigid plate. In 9 patients, an average wedge size of 7.1 degrees was resected leaving the medial cortex of the proximal tibia intact (group 1). In 6 patients, the medial cortex of the proximal tibia was unintentionally fractured during surgery when an average 10.7 degrees wedge was resected (group 2). Postoperatively, patients were monitored with serial radiostereometric analysis (RSA), conventional radiographs, and clinical evaluation for 1 year. In group 2, RSA revealed a 1.3-mm increase in lateral displacement of the distal tibial segment within 3 weeks following surgery. Twelve weeks after surgery, micromotion between tibial segments was below the precision of the RSA setup in 14 of 15 patients. These findings indicate that in cases with larger wedge sizes (>8 degrees), fracture of the medial cortex of the proximal tibia was frequent and resulted in significant lateral displacement of the distal tibia relative to the tibial plateau. In such cases, prophylactic additional medial fixation rather than lateral L-plate fixation alone is advised to minimize the propensity for lateral displacement of the distal tibia and to avoid subsequent loss of correction.

Tibiale Umstellungsosteotomien sind zur Behandlung einer medialen Gonarthrose weit verbreitet. Der ideale Patient ist aktiv, junger als 55 Jahre und weist eine unikompartimentare Arthrose bei bandstabiler Varusdeformitat

In high tibial closing-wedge osteotomies (HTO), closure of an osteotomy gap after resection of a bony wedge can be associated with a fissure of the medial cortex of the tibial head (MCT). The effect of a broken MCT on the recurrence of varus deformity is disputed. In this study, serial roentgen stereometric analysis (RSA) was used to determine the fixation stability of a rigid internal "L" plate after HTO. Full weight lower limb radiographs were used to determine the sagittal alignment in patients with varying degrees of varus malalignment and correction over time. Forty-two patients with varus gonarthrosis stage I-III (Ahlback) were treated with HTO and internal fixation with an L-shaped rigid plate. Patients were followed by serial RSA, conventional radiographs, and clinical evaluation (Hospital of Special Surgery score) over a 12-month period. In 19 of 42 successive patients, an average wedge size of 6.9 degrees was resected leaving the MCT intact (group 1). In 23 of 42 of patients, the MCT was unintentionally fissured during surgery when an average 10.3 degrees -wedge was resected (group 2). In group 2, RSA revealed a fivefold increase in lateral displacement of the distal tibial segment within 3 weeks after HTO. Twelve weeks after HTO, translations between tibial segments were below the accuracy of the RSA setup in the majority of patients. Group 1 patients demonstrated a higher initial fixation stability, less occurrence of varus deformity, and a higher HSS score compared to patients with larger wedge sizes and frequent fracture of the MCT (group 2). Before bone healing is achieved, the integrity of the MCT plays a crucial role for the clinical and radiological outcome after HTO.

Background Reliable fixation of the soft hamstring grafts in ACL reconstruction has been reported as problematic. Hypothesis The biomechanical properties of patellar tendon (PT) grafts fixed with biodegradable screws (PTBS) are superior compared to quadrupled hamstring grafts fixed with BioScrew (HBS) or Suture-Disc fixation (HSD). Study Design Controlled laboratory study with roentgen stereometric analysis (RSA). Methods Ten porcine specimens were prepared for each group. In the PT group, the bone plugs were fixed with a 7 · 25 mm BioScrew. In the hamstring group, four-stranded tendon grafts were anchored within a tibial tunnel of 8 mm diameter either with a 7 · 25 mm BioScrew or eight polyester sutures knotted over a Suture-Disc. The grafts were loaded stepwise, and micromotion of the graft inside the tibial tunnel was measured with RSA. Results Hamstring grafts failed at lower loads (HBS: 536 N, HSD 445 N) than the PTBS grafts (658 N). Stiffness in the PTBS group was much greater compared to the hamstring groups (3500 N/mm versus HBS = 517 N/mm and HSD = 111 N/mm). Irreversible graft motion after graft loading with 200 N was measured at 0.03 mm (PTBS), 0.38mm (HBS), and 1.85mm (HSD). Elasticity for the HSD fixation was measured at 0.67 mm at 100 N and 1.32 mm at 200 N load. Conclusion Hamstring graft fixation with BioScrew and Suture-Disc displayed less stiffness and early graft motion compared to PTBS fixation. Screw fixation of tendon grafts is superior to Suture-Disc fixation with linkage material since it offers greater stiffness and less graft motion inside the tibial tunnel. Clinical Relevance Our results revealed graft motion for hamstring fixation with screw or linkage material at loads that occur during rehabilitation. This, in turn, may lead to graft laxity.

The aim of this study was to compare the effect of extracorporeal shock wave therapy (ESWT) in patients with chronically painful proximal plantar fasciitis with a further conventional conservative treatment. Forty-seven patients (49 feet) with a previously unsuccessful nonsurgical treatment of at least 6 months were randomized to two groups. Heel cups had to be worn throughout the study. Group 1 (25 heels) was treated immediately with three sessions of ESWT (3000 shock waves/session of 0.2 mJ/mm2) at weekly intervals. The patients of group 2 (24 heels) continued nonsurgical treatment (iontophoresis with diclofenac and an oral nonsteroidal anti-inflammatory drug) for 12 weeks. After this period they were treated using the protocol of group 1. No significant difference of pain and walking time after further nonsurgical treatment (3 months) was seen in group 2. At 12 weeks after ESWT, the pain estimation on the visual analogue scale (VAS) for activities of daily living diminished significantly by 62.9% in group 1 and by 63.0% in group 2. The comfortable walking time had increased significantly in both groups. Two years after ESWT, pain during activities of daily living decreased by 94% in group 1 and by 90% in group 2 on the VAS and the comfortable walking time had increased significantly in both groups.

Purpose: This prospective study was designed to assess postoperative changes in patellar tendon length after removal of its central one third for anterior cruciate ligament (ACL) reconstruction using precise Roengen stereometric analysis (RSA). Type of Study: Prospective clinical study. Methods: Ten consecutive patients underwent arthroscopically assisted ACL reconstruction using the mid-third bone–patellar tendon–bone (BPTB) autograft. The tendon defect was left open and the paratenon was approximated with sutures. Tantalum beads were inserted in the distal part of the patella and in the tibial tuberosity through the bone defects. The distance between the tantalum markers in the patella and the tibial tuberosity was measured with RSA at the first day and at 1, 2, 3, 6, and 12 months after surgery. Results: A decrease of patellar tendon length was observed in all cases. The amount of shortening averaged 1.6 mm (range, 0.5 to 3.2 mm), 3.2% of the initial length. In 4 patients, tendon shortening was detected during the first 4 weeks after surgery. In 6 cases, decrease of patellar tendon length started between the fourth and the eighth week. The shortening process continued in 8 knees until the 12th week. No further changes in patellar tendon length were observed after the 12th postoperative week. In 2 patients, shortening of the patella tendon exceeded 2 mm. The amount of patellar tendon shortening was not related to anterior knee pain. Conclusions: After removing the BPTB autograft, irreversible shortening of the remaining two thirds of the patellar tendon occurred during the first 12 postoperative weeks. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 8 (October), 2002: pp 859–864

Precise digital data of the internal femoral anatomy are necessary to develop new prosthetic implants with computer-aided design (CAD) techniques. Thirty human cadaveric femurs of central European origin were analysed by high precision computed tomography (CT) using thin slice and high resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of the cortical bone geometry. The CT threshold for cortical bone was optimized by comparison with saw cuts of macerated femurs. For each specimen a three-dimensional (3D) model of the cortical femur was calculated by the CAD system based on the processed CT data. Virtual 3D models of the 30 femurs were used to adjust a hypothetical stem to the proximal femur anatomy by repeated virtual implantations. The CAD system allowed for evaluation of anatomical parameters after hip reconstruction, amount of bone removal, and cortical bone contact. The fit and fill of the stem could be tested before clinical application and implant-related problems could be corrected.

STUDY DESIGN The intervertebral stability of bony consolidated anteroposterior lumbosacral spondylodesis is evaluated by roentgen stereophotogrammetric analysis and direct surgical exploration before and after removal of the internal fixator. OBJECTIVES To determine the remaining in vivo stability of spinal arthrodesis solely retained by a bony integrated carbon fiber cage. SUMMARY OF BACKGROUND DATA Roentgen stereophotogrammetric analysis studies on posterolateral lumbar fusions demonstrate primary spinal stability after additional dorsal instrumentation, which is retained during bony fusion healing. Animal models show a persistent stabilizing effect of the fixator despite the presence of bony fusion. Although direct surgical inspection is the most reliable method to evaluate fused vertebrae, roentgen stereophotogrammetric analysis has also proven to be a highly accurate method to evaluate spinal stability. METHODS In 10 patients lumbosacral fusion was performed using carbon interbody implants and an internal fixator. Ten months after initial surgery (range 7-15 months) the internal fixation was removed to reduce local soft tissue impingement as soon as bony fusion was achieved. Fusion site exploration in the course of instrumentation removal was performed by applying distraction, compression, and torque to the grafted area under fluoroscopic control. Any motion indicated a pseudarthrosis. Lumbosacral stability was evaluated by serial roentgen stereophotogrammetric analysis after fusion and after instrumentation removal. RESULTS During instrumentation removal the mechanical stress test under fluoroscopic control did not indicate pseudarthrosis. After instrumentation removal, roentgen stereophotogrammetric analysis measurements revealed a nonsignificant increase in lumbosacral micromotions within the fused segment with 0.14, 0.31, and 0.44 mm in the transverse, vertical, and sagittal axes, respectively. CONCLUSIONS The internal fixator could be removed without endangering the stability of the fusion. Direct surgical exploration confirmed the adequacy of roentgen stereophotogrammetric analysis as a reliable in vivo method to evaluate lumbosacral stability after anteroposterior fusion.

The paper will present the preliminary design of the so called GICON® - Tension Leg Platform (TLP) as an innovative foundation concept for floating offshore wind turbines. Preliminary results from model basin tests are also shared. This includes the currently ongoing research of comparing calculated and experimental data obtained through extensive wind and wave tank experiments with a scale model of an offshore wind turbine at the Maritime Research Institute Netherlands (MARIN) in June 2013. These tests have provided insights regarding the dynamic characteristics of the GICON®-TLP by analyzing the system’s response to different load cases. The experiments included wind and wave loads, which represent three different sea states, each with three different directions of inflow. The chosen load cases correspond to the proposed location in the German Baltic Sea where the full scale prototype will be erected.

The aim of this study was to investigate the effect of extracorporeal shock wave therapy (ESWT) on the ultrasonographic appearance of chronically painful, proximal plantar fasciitis.Twenty-two patients with a unilateral proximal plantar fasciitis were prospectively enrolled after unsuccessful conservative treatment lasting 6 months. The contralateral plantar fascia was used as the control. ESWT (3x3000 shock waves/session of 0.2 mJ/mm2) was performed at weekly intervals. The thickness of the plantar fascia was measured ultrasonographically about 2 cm distal of the medial calcaneal tuberosity. Pain estimation on a visual analogue scale (VAS) and the comfortable walking time were recorded. No local anaesthesia was applied. Follow-up was done at 6, 12 and 24 weeks.Before ESWT, the plantar fasciitis side was ultrasonographically significantly thicker than the control side (p0.05), whereas 6 months after ESWT, the thickness of the fascia was no longer significantly different. The decrease in thickness of the plantar fasciitis side was significant (p0.05). Pain during activities of daily living decreased by 79% according to the VAS, and the comfortable walking time increased, both significantly (p0.01). In patients with little pain (VAS30), the thickness of the plantar fasciitis side was significantly less (p0.01) compared with patients who still suffered more pain (VAS30).After ESWT, the thickness of the plantar fascia in patients with plantar fasciitis decreased, pain and walking time improved (all significantly).

We investigated a press-fit anatomically shaped hip stem made of carbon fiber-reinforced composite material in a prospective clinical study. The intention of the design was that a surface of interlaced carbon fibers in the proximal part would achieve metaphyseal fixation. A total of 51 carbon stems were implanted in 48 patients (30 women and 22 men). Mean age at operation was 59 years. The patients were followed clinically, radiologically, and with computed tomography. At 6-year follow-up, aseptic loosening was observed in 47 hips (92%). Forty stems were revised on average 30 months (range, 9-58 months) postoperatively. All revised carbon stems showed fibrous fixation without any bony on-growth. No osteolysis was seen. Histologically, no carbon wear or inflammatory reactions were observed. Only 4 cases had a good clinical result with bony fixation on computed tomography scan. The carbon fiber prosthesis without effective ingrowth or on-growth irregularities showed a high rate of early loosening.

The femoral "thigh spur", a cortical septum in the region of the lesser trochanter of the human femur, was first described and named by the German anatomist Merkel in 1874, but it was never examined in detail. To evaluate the frequency and the shape of this structure, a combined anatomical and radiological study was performed using saw-cuts from specimens, high-resolution CT and conventional radiography.Thirty human cadaveric femora of central European origin were analyzed by high-precision computed tomography (CT) using thin slices and high-resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of high-density bone formations and for three-dimensional imaging. Additionally three macerated femur specimens were cut exactly corresponding to the CT slices. The computed images were validated with the anatomical saw-cuts.A dense trabecular ridge protruding endosteally from the posteromedial cortex was found in all femora. This cortical septum reaching from the femoral neck to the distal part of the lesser trochanter separated the femoral cavity from the cancellous bone inside the lesser trochanter. On conventional radiography the femoral thigh spur could be visualized best in the frog-lateral view of the hip.The internal calcar septum is a constant cortical structure. It should be recognized when radiographs or CT images of the proximal femur are interpreted. It could be of importance for metaphyseal fitting of an endoprosthetic stem.

To develop realistic forest machine simulators is a demanding task. A useful simulator has to provide a close- to-reality simulation of the forest environment as well as the simulation of the physics of the vehicle. Customers demand a highly realistic three dimensional forestry landscape and the realistic simulation of the complex motion of the vehicle even in rough terrain in order to be able to use the simulator for operator training under close-to- reality conditions. The realistic simulation of the vehicle, especially with the driver's seat mounted on a motion platform, greatly improves the effect of immersion into the virtual reality of a simulated forest and the achievable level of education of the driver. Thus, the connection of the real control devices of forest machines to the simulation system has to be supported, i.e. the real control devices like the joysticks or the board computer system to control the crane, the aggregate etc. Beyond, the fusion of the board computer system and the simulation system is realized by means of sensors, i.e. digital and analog signals. The decentralized system structure allows several virtual reality systems to evaluate and visualize the information of the control devices and the sensors. So, while the driver is practicing, the instructor can immerse into the same virtual forest to monitor the session from his own viewpoint. In this paper, we are describing the realized structure as well as the necessary software and hardware components and application experiences.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.