Transport Research Arena 2014, Paris

A Novel Robotic Handling Device integrated on a Freight Urban Robotic Vehicle

G. G. Muscolo, L. de Leonardo, G. Pietronave, A. Dinale, M. Zoppi, F. E. Cepolina* PMAR Lab (Laboratory of Design and Measurement for Automation and Robotics), Department of Machines, Mechanics and

Design, Scuola Politecnica, Universita’degli studi di Genova (Italy)

Abstract

FURBOT (Freight Urban RoBOTic vehicle, n. 285055) is a project funded by the European Union within the 7th Framework Programme. Its aim is to develop a new concept architecture of light duty full electrical vehicle for efficient sustainable urban freight transport. In this article, the authors present a novel robotic handling system especially designed for the FURBOT vehicle. The handling system has been designed in order to perform the loading/unloading operation in an autonomous way, without any manpower. Using this system, it will be possible to handle two Euro Pallet (800x1200mm) or dedicated boxes with identical dimensions. The load will be picked up directly from the ground or a step with a maximum height of 150mm. An additional aid is given by the active suspensions of the vehicle, which allow lowering the chassis and facilitate the loading/unloading operation. Keywords: Freight urban robotic vehicle; loading-unloading pallets; robotic handling device; forklift.

Résumé

FURBOT (fret urbain véhicule robotisé, n. 285055) est un projet financé par l'Union européenne au titre du 7e programme-cadre. Son objectif est de développer un nouveau concept architectural de véhicule électrique complet légers pour le transport urbain de marchandises efficace et durable. Dans cet article, les auteurs présentent un système de manutention robotisé roman spécialement conçu pour le véhicule FURBOT. Le système de traitement est conçu pour effectuer l'opération de chargement / déchargement de façon autonome, sans la main-d'oeuvre. Grâce à ce système, il sera possible de gérer deux palettes Euro (800x1200mm) ou boîtes dédiés aux dimensions identiques. La charge sera prélevée directement sur le sol ou une étape avec une hauteur maximale de 150mm. Un dispositif d'aide supplémentaire est donnée par les suspensions actives du véhicule, ce qui permet l'abaissement du châssis et de faciliter l'opération de chargement / déchargement. Mots-clé: Véhicule urbain robotique; chargement-déchargement, dispositif robotique; chariot élévateur.

* Corresponding author: Giovanni Gerardo Muscolo. Tel.: +390103532843; fax: +390103532834. E-mail address: muscolo@dimec.unige.it.

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1. Introduction

1.1. Freight Transport in Urban Area

Statistic shows that freight transport plays an important role in urban transport context. In fact 20-30% of the urban traffic is due to goods movement, and this influence the air pollution level of about 15-50%, depending on the kind of considered pollutant (Dablanc, 2007a). Furthermore the increasing number of vehicle in urban area, contribute to raise traffic jams and consequently the atmospheric pollution (Yannis et al., 2006). The large majority of cities, especially in Europe, have not yet found adequate solutions to optimise the urban movement of goods. Neither the municipalities nor delivery companies make the first step necessary to improve the freight transport, both from technological and logistic perspective. On one hand, city governments expect delivery companies to set up new logistics services that can fit to the emerging needs of the customers and retailers; on the other hand, logistics providers wait for municipalities to arrange new services that facilitate new businesses, guaranteeing low risk and high profit. (Dablanc, 2007a). A combination of commercial initiatives and government policies will be necessary in developing a sustainable urban freight system (Anderson et al., 2005). Zunder and Ibanez (2004), described the results of a questionnaire form the project BESTFUS, in which the freight policy of European governments is discussed. It is clear how freight policy is left aside while public transport and road infrastructure take the majority of resources. 25% declared not to have anyone in charge of freight policy and 44% had less than a full-time employee working in the matter. A sustainable freights transport has to fulfil all the following objectives (Behrends et al., 2008): • to ensure the accessibility offered by the transport system to all categories of freight transport; • to reduce air pollution, greenhouse gas emissions, noise to levels without negative impacts on the health of

the citizens or nature; • to improve the resource- and energy-efficiency and cost-effectiveness of the transportation of goods, taking

into account the external costs; • to contribute to the enhancement of the attractiveness and quality of the urban environment, by avoiding

accidents, minimizing the use of land and without compromising the mobility of citizens.

1.2. FURBOT project Overview

Taking into account the new paradigms for urban transportation, such as; energy efficiency, eco sustainability, dexterity and automated driving, arises the European funded project Freight Urban RoBOTic vehicle (FURBOT). The project’s primary goal is the development of a new architecture of fully electric vehicle with embedded automated handling device for freight transport within highly urbanized areas of European cities. Within the FURBOT project a first prototype of the vehicle with the integrated handling device will be manufactured, this will led to the demonstration of the concepts and ideas implemented; and to prove its functionality, applicability and advantages as an integrated transport system. Particular attention has been paid to the design approach, which try to integrate the different parts harmonically. Each component is designed in a modular way, so that it is possible to re-use the same technology in different vehicles developed in future researches. Furthermore, the whole vehicle life-cycle issues are taken into account, including manufacturing, use, maintenance and recycling costs. It is also important to satisfy the end-user requirements, so we have to consider the point of view of the municipalities, public authorities and delivery companies. The mobile platform integrates electrical modules for power generation, vehicle propulsion and driving, together with the control modules, these are explained in more detail in Dinale et. al., (2013). The vehicle presents a new frame-platform structure which is designed in order to envelop tightly the payload (including the new robotic tool for freight manipulation) and limit the total vehicle size, making possible to make consignment also in narrow streets and less accessible area of the city. The reduced mass of the vehicle allows the realization of active driving control, taking advantage of the included X-by-wire transmission. It is also important to underline that FURBOT vehicle is electrically powered, so it is environmentally friendly. An innovative battery and energy management system is introduced to improve the energy efficiency. In order to

Giovanni Gerardo Muscolo et al./ Transport Research Arena 2014, Paris

enhance the driver experience, the vehicle is equipped with an intelligent system, which monitors the internal and external state of the vehicle itself, giving the necessary support during the delivery process. Freight boxes have been purposely designed together with the architecture of the FURBOT vehicle: the boxes have standard size, same external shell and grasping handles. Their structures are dedicated to different kind of freight (Cepolina, 2013). Several constrains have been taken into account in order to realize a suitable and feasible handling device for the loading/unloading of Euro-pallets (or Boxes with similar bottom part). The constraints are related to the vehicle’s chassis structure and the handling system is designed in parallel with the later to achieve an easy integration of the system. At the same time, the handling device is conceived as a separate system of the vehicle becoming hence an optional service. In order to optimize the robotic handling device that will be embedded on the vehicle and to achieve a functional design with a dexterous workspace, different solutions have been proposed and studied. In order to maintain the masses to their lowest level, high-strength non-conventional materials and lean parallel kinematic structures have been considered. The paper is structured as follows: Section 2 describes in detail the most important parts considered for the conceptual and functional design of the FURBOT robotic handling device. Section 3 describes the characteristics of the proposed solution and shows the computational tests on the new integrated forklift. Section 4 conclusions and future work are presented

2. Conceptual and Functional Design of the FURBOT Robotic Handling Device

2.1. General Constraints of the Robotic Handling Device

In order to drive the design and development of the handling device, different constrains were set: • since about 70% of the world's total road distance carries traffic on the right, the loading/unloading process is

realized from the right side of the vehicle. In this way it is possible to reduce the time and the effort; • the loading capacity of FURBOT vehicle is equal to two Euro-pallets (800x1200mm) or two dedicated boxes

with the same dimensions. A loaded configuration of the vehicle is presented in the Figure 1. • the loading bay is able to support a payload of maximum 1 Ton. We suppose that the weight is equally

distributed between the two pallets (or boxes), so 500 kg for each; • The loading of the pallets or boxes is done from the 800 mm side; • the load can be picked up directly from the ground level or from a step (typically the pavement) with a

maximum height of 150mm at a maximum distance of 300 mm from the vehicle’s side;

Fig. 1. Sketch of the FURBOT vehicle (first version)

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2.2. The proposed solution: main hypotheses and requirements

The handling device has been designed in order to realize the loading/unloading operation on the right side of the vehicle. The loading bay space determines heavily the length of the vehicle. Each component of the handling system is designed in order to simplify as much as possible the loading/unloading operation. The interface between the frame of the vehicle and the handling devices must be simple and robust. The weight of the handling system must be as less as possible in order to achieve the main target of the project to limit the weight of the entire vehicle and consequently the energy consumption. At the same time a simple mechanism to load and unload the freights guarantees these targets and the operative robustness.

In the following subsection, the main issues that have been taken into account for the design of the handling system will described.

2.2.1. Position of the pallet: In order to load correctly the pallet (see Fig. 3), it is necessary to verify that the following pre-conditions/assumptions are satisfied: • The pallet is placed on the street or low height pavement level. • The pallet is positioned in order to be forked from the shortest side (hereafter it will be called operating side). • The pallet is located in a horizontal position. The loading/unloading system is developed in order to move the pallets from the ground to the vehicle platform’s level. This movement can be assured through a system that realized 2 DoF: vertical and transversal displacement. A further DoF would allow loading both the pallets with a unique loading device by translating the device itself through the inner space of the loading bay; however, this solution would imply an increase in the weight of the vehicle. Considering the traditional approach of loading/unloading Euro-pallets and boxes, the authors proposed to modify and adapt the manual forklift of Figure 4 and to use it as end-effector of the robotic handling device of the FURBOT vehicle. Two Euro-pallets (or boxes) (800x1200 mm) will be loaded/unloaded and positioned in the internal part of the vehicle as in Figure 5.

2.2.2. Concept design: By studying the functional aspects and reengineering the commercial forklift (see Fig. 4) a completely new handling device has been developed. In order to permit a smooth integration of the device to the FURBOT

(a)

Fig. 2. (a) Organization of loading bay inside the vehicle; (b) Loading process sketch (top view) (b)

Giovanni Gerardo Muscolo et al./ Transport Research Arena 2014, Paris

vehicle the handle and the rear wheels have been removed. Moreover, the lifting pump is replaced with a different actuator and the frame structure is optimized.

Fig. 3. Euro-pallet (units are in mm) (a) and FURBOT box MultiBox (b)

Fig. 4. Manual forklift (courtesy of EDIL m.a.r.c.)

2.2.3. Loading/unloading process: In the FURBOT vehicle, the loading/unloading process is completely automated and does not require any manpower or human intervention. Once the vehicle has been positioned correctly in the proximity of the pallet, the driver has only to supervise the process and stop it in case of an emergency. It is crucial, for a correct loading, to have the handling device perfectly aligned to the pallet slots; otherwise the freights or the device can be damaged during the process. Assuming the vehicle is positioned correctly, respecting the tolerances and maximum misalignment errors; the process can be summarized in the following steps: 1. the vehicle is parallel to the pallet, or box, at a maximum distance of 300mm, 2. using the vehicle’s active suspension, the chassis is lowered towards the ground (Fig. 5b), 3. the handling device forks and lifts up the pallet, then translates and lowers it onto the loading bay of the

vehicle (Fig. 5b and Fig. 5c), 4. the vehicle is lifted up again to the driving configuration (Fig. 5d). The unloading process follows the same steps but in reverse order.

(a) (b)

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Fig. 5. FURBOT loading cycle. (a) Vehicle en-route towards the freight; (b) FURBOT lowered during loading operation; (c) loading operation completed; (d) FURBOT lifted up, ready to move.

2.2.4. FURBOT handling device and vehicle actuation: The actuation of the handling device and the vehicle are independent with respect to each other, in this way the handling device becomes an standalone component that can be fitted in other vehicles regardless if these are electric or not. The robotic handling device has been developed to be as simple as possible with a total of two DOFs; being these horizontal (Y direction) and vertical (Z direction) motion (see Fig. 5). These motions are generated by hydraulic actuators: two hydraulic cylinders realize the horizontal motion in the Y direction, translating the handling device out of the loading bay of the vehicle; a third hydraulic cylinder replaces the lifting actuator, realizing the necessary motion in Z direction to lift up the pallets. The FURBOT vehicle actuation system can be divided in two, one of which is used during the loading/unloading process by means of active suspension, the other one is the traction system of the vehicle. The suspension is similar to the one used widely in off-road vehicles. It is made of hydraulic cylinders that can adjust the height of the chassis with respect to the ground depending on the height in which the pallet/box is located. In the FURBOT vehicle the hydraulic unit that commands the handling device is the same that controls the active suspension. During locomotion of the vehicle the suspension is set to a predetermined height and the compensation to irregularities in the terrain is given by a nitrogen reservoir attached to the cylinder that acts exactly as the springs in common suspension systems. Thanks to the nitrogen tank and a valve block located between the cylinder and the tank, the suspension can achieve absolute rigidity during loading/unloading operation. The traction system is realized by means of electric motors located in the wheels or on their vicinity, different architectures were studied some of which are described in the following: • Four traction motors (3.75kW each) placed at a predefined distance axially to each wheel and linked by a

rigid shaft without the need of a gearbox to maintain motors’ efficiency (Fig. 6). This architecture permits to introduce a high level of flexibility to the vehicle by having not only four traction wheels but also four steering wheels.

• Four traction motors (3.75kW each) mounted directly inside the wheels, this architecture, although the best in terms of efficiency was discarded because of the complexity to design the active suspension system, needed for a proper loading/unloading operation.

• The decided solution implemented in the design of the FURBOT vehicle, is that of a more traditional vehicle with front steering wheels and rear traction realized by two motors (7,5 kW each) mounted directly to the rear wheels; this solution represents the best compromise between energy efficiency and active suspension design complexity.

Giovanni Gerardo Muscolo et al./ Transport Research Arena 2014, Paris

Fig. 6. FURBOT vehicle frame (early version)

3. FURBOT Robotic Handling Device

3.1. Robotic Handling Device

The final solution of the robotic handling device is composed of a structural frame with one DoF (Fig. 7) on which the newly designed forklift is positioned adding the second DoF. The structural frame is composed of two pairs of linear guides located one on top of the other on each side of the frame, the housing steel plate of the linear guides connects the parts A, B and C together (Fig. 7). The first degree of freedom is actuated by two hydraulic cylinders mounted on the sides of the system (actuators 1 and 2 in Fig. 7). Part C of the frame is the only part without any motion, being the fixed point of contact between the handling device and the vehicle’s chassis. On the other hand, parts B and A are actuated by the hydraulic cylinders realizing the translation (Y direction) of the handling device in two stages. Actuator 1 allows the motion of the part B with respect to the fixed part C, being this motion stage 1 of the handling device; actuator 2 allows the motion of part A thanks to the linkage between the actuator and the forklift, being this the stage 2. The back side of the forklift is connected to Part A while in the front is located Actuator’s 2 piston shaft. The two stages of motion permit the handling device to translate well beyond the minimum requirements of 300mm. A third hydraulic cylinder is located in the back of the forklift permitting the motion in the Z direction, thus the second DoF of the handling device. Fig. 8a shows the complete robotic handling device in a digital mock-up, the configuration shown is the idle state of the device where all the actuators are retracted and the device is inside the loading bay of the vehicle with the exception of the front rollers; that in any case are within the total width of the vehicle including the wheels and body. Fig. 8b shows the relative motion of each parts of the handling device as if during the loading or unloading process.

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Fig. 7. Robotic handling device frame

3.2. Computational tests of the handling device

The robotic handling device was designed using the CAD software (Pro/ENGINEER) and the final analyses of the structure were done using ANSYS. The part B of Fig. 7 has been pointed to be the critical part of the robotic handling device structure. While the system is symmetric with respect to the Y plane it is not loaded in a symmetric way; thus, the structure is analyzed considering only forces and torques that can cause critical stress to this part. The material used for the structural analysis is an AISI 6000 series steel with tensile strength values between 415 to 1230 MPa. Fig. 9 shows some of the results obtained from the structural analysis; in particular the deformation analysis is depicted. The maximum deformation is equal to 45.5 mm. applying a force of 10000 N in Z direction (see Fig. 7), the maximum deformation of part B occurs in the proximity of the contact point with part A. However, the value is considered not to be dangerous; this, because during simulations many simplifications were done, the most important one is the disregard of the opposing forces exerted by the handling device rollers when in contact to the ground. Also, the used load value equal to 1000 kg (10000N) is overestimated with respect to the maximum permitted weight of the freight to be carried, 600 kg.

(a) (b)

Fig. 8. Robotic handling device digital mock-up: a) closed configuration, b) open and lifted configuration

Giovanni Gerardo Muscolo et al./ Transport Research Arena 2014, Paris

Fig. 9. Computational tests of the robotic handling device frame

4. Conclusions and Future works

The paper presents a preliminary design of a novel robotic handling device that will be integrated within the electric vehicle of the Freight Urban Robotic vehicle European project (FURBOT). The paper focuses on the design of the robotic handling device giving an idea of the steps followed to its conception. An initial conceptual design is presented together with the general rationale of the complete system, to then present the final design solution that will be implemented and results of the structural analysis. A first prototype of the Robotic handling device is being manufactured and will be assembled in the first prototype of the FURBOT vehicle, an initial digital mock-up of the complete vehicle is shown in Fig. 10.

Fig. 10. Digital mock-up of the robotic handling device installed on the FURBOT vehicle

The project objectives are well in line with the position of ERTRAC expressed in the “ERTRAC Road Transport Scenario 2030” (October 2009); the position of OECD-ITF delivered in “Figuring Out the Future of Transport” (20 October 2010); as well as the position of UITP European Union expressed in the position paper of February 2008 “Towards a new culture for urban mobility” and with the position about the mobility modelling disseminated by the International Energy Agency in “Informed analysis of sustainable transportation” and with all the recent documents on sustainable transport edited by most of the countries (Japan, USA and Europe). With the change in transport paradigm, it becomes clear the need of lean, agile and sustainable freight transport systems for urban environments; this necessity will surely grow in next years, ensuring a place in the market for solutions such as the one proposed in the FURBOT project.

Acknowledgements

This work is developed within the FURBOT project funded under the Seventh Framework Program (FP7, GC.SST.2011.7-10. Grant agreement no. 285055). We would like to acknowledge European Commission and

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the partners of the project (DIME-Università di Genova, INRIA, Bremach industries SRL, ZTS VVU Kosice as, Università di Pisa, Persico s.p.a., Mazel Ingenieros, S.A. Transportes Colectivos do Barreiro).

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