Study on Automatic Spray of Distribution Boom System of Truck- Mounted Concrete Pump

Transcription

1 The Open Mechanical Engineering Journal, 2008, 2, Open Acce Study on Automatic Spray of Ditribution Boom Sytem of Truck- Mounted Concrete Pump Shu-Wen Zhou, Li-Xin Guo * and Si-Qi Zhang College of Mechanical Engineering and Automation, Northeatern Univerity, Shenyang , China Abtract: Truck-mounted concrete pump have been adopted in many contruction project. However, the invetigation about the automatization or robotization of ditribution boom ytem of the truck-mounted concrete pump are very cattered. In thi tudy, a cheme of automatic concrete pray of the ditribution boom ytem of the truck-mounted concrete pump ha been preented and dicued. The concrete pray proce and the kinematic of the boom ection were analyzed including it invere kinematic problem. Tranient dynamic analyi wa performed to validate the effect of the new control ytem on the boom ytem bae on the flexible body co-imulation among ANSYS oftware, ADAMS oftware and Matlab/Simulink oftware. A three-dimenional imulation wa programmed to imitate the proce of automatic pray and verify the control algorithm. The imulation reult how that the ytem can pour concrete on a long narrow area automatically thereby atifying, and the trajectory movement of boom mechanim. Keyword: Concrete pump, boom ytem, automatic pray, co-imulation. INTRODUCTION The pumping of concrete i univerally accepted a one of the main method of concrete ditribution and placement in the field of contruction. A a favorable placing option, it provide advantage over other method uch a crane and kip, hoit and conveyor for building contruction. Therefore, the ue of concrete pump i increaing throughout the world, along with the pumping technologie, that are alo becoming more reliable. In order to improve working efficiency of concrete pumping, much attention ha been given to the automatization or robotization of the ditribution boom ytem of Truck-mounted concrete pump [1-7]. In many cae, pumping concrete automatically intead of manual operation will leen the operator labor intenity and dramatically increae the productivity (Fig. 1). However, for a atifactory implementation of automatic concrete ditribution there are many problem needed to be olved. For example, although a robotization to the ditribution Fig. (1). Pumping concrete for reidential project. *Addre correpondence to thi author at the College of Mechanical Engineering and Automation, Northeatern Univerity, Shenyang , China; lxguo@mail.neu.edu.cn X/08 boom ytem of concrete pump i not difficult in principle, it i not eay to eliminate the vibration problem during automatic concrete ditribution in practice [8, 9]. To olve thi problem, it need to ytemically conider the trajectory planning of precribed aignment, multi-body dynamic, 2008 Bentham Open

2 Ditribution Boom Sytem of Truck-Mounted Concrete Pump The Open Mechanical Engineering Journal, 2008, Volume 2 85 vibration of the boom ytem, dynamic control of kinematic and kinetic, etc. during the proce of automatic concrete ditribution. Therefore, in thi tudy, an automatic pray ytem of pumping concrete wa chemed. We ued finite element method, dynamic method, control method a well a their co-imulation by ANSYS oftware, ADAMS oftware and Matlab oftware to validate the effect of the whole ytem on the automatic praying of the ditribution boom pump. The reult might provide ueful reference for deign and development of the ditribution boom ytem of Truckmounted Concrete Pump. ANALYSES ON THE AUTOMATIC SPRAY SYSTEM Normally, the pump operator control the entire machine via a radio remote control unit. Thi include not only the movement of all ection (boom arm) of the multi-ection boom, but alo to the volume of concrete to be poured. Moreover, the control of operation equence i ubmitted to guarantee that the movement of every ection of boom and the location of ditributed concrete are a mooth a poible [7]. Traditionally, the boom control i accomplihed by uing a ingle joytick. In thi cae, a pump operator control each individual boom hydraulic cylinder and the lewing gear, preferably directly proportional, in order to ecure a precie poitioning of the end hoe, on the contruction ite [7]. Thi mean the operator ha to hift at leat five joytick in turn. However, to control the boom-end hoe move along a long narrow field under the operator manipulation i not an eay tak. It i almot impoible for an operator to control accurately and moothly the hoe end through a long linear narrow field. Therefore, a trong man i needed to arrange and regulate the end hoe poition, ince the end hoe i made of ynthetic rubber that can be bent. The automatic pray ytem wa developed to implify the pray operation in thi tudy. The pray operation proce i that in which the operator move the end hoe from one end of a wall (a precribed trajectory) to another end, i.e. from Point 1 to Point 2 (hown in Fig. (2)), and let the control ytem record the boom ection poture (relative rotational angle of every boom ection). Baed on the two end of the wall, the control ytem draw out a traight-line equation, i.e. the trajectory of the end hoe. Then the traight-line i divided into a number of ection and correpondingly, the poture of the boom i olved uing Jacobian peudoinvere algorithm. Finally, the boom mechanim, driven by a hydraulic ytem, can pour the wall automatically according to the olved poture one by one from the 2nd point to the 1t point. During praying operation of the concrete, the operator ha to adjut the boom movement tep and concrete flow velocity if neceary. About redundant robotic manipulator, different technique and criteria have been ued to reolve the redundancy, while optimizing certain objective. Method ued to reolve the redundancy of the manipulator include Jacobian peudoinvere algorithm [10, 11], ingular value decompoition [12, 13], damped leat-quare method [14, 15], joint torque optimization [16], minimal bae reaction [17], neural network [18, 19], and genetic algorithm [20], et al. The ingular value decompoition ha played an important part in olving invere kinematic problem of redundant robot manipulator [12, 13]. The damped leatquare method, which i baed on the ingular value decompoition, i an efficient method for eliminating numerical problem at the ingularitie [14, 15]. In thi paper, we aume that the motion poture planning of the boom mechanim during concrete pouring proce i defined within ingularity avoidance, therefore, the conventional method, Jacobian peudoinvere algorithm, i ued to reolve the redundancy of the boom mechanim, ince it i imple and effective. 2 nd point Fig. (2). Route of the end hoe. 1 t point KINEMATIC RESOLUTION OF THE REDUN-DANT BOOM SYSTEM A manipulator i aid to be redundant when the dimenion of the tak pace m i le than the dimenion of the joint pace n. In cae of a redundant manipulator, r = n-m (r 1) i the degree of redundancy [9, 10]. The concrete boom ytem can be conidered a a redundant manipulator, a hown in Fig. (3). It include four ection, four hydraulic cylinder and one turntable. All the ection are conidered a rigid bodie. In practice, there are mall flexural diplacement in all the ection, during praying proce of concrete. Thee diplacement can be compenated by the control ytem. For the multiple-arm boom ytem of a truck-mounted concrete pump, the end hoe poition i a function of joint variable of boom ection. The kinematic function i defined a: X = f ( ) (1) where X i the m 1 ( m = 3) poition vector of the end hoe, and i the n 1 ( n = 5) joint angle vector. n > m, in the cae of redundant manipulator. The differential kinematic function i given by X = J (2) where X i the 3 1 velocity vector of the end hoe, i the 5 1 joint velocity vector, and J i the 5 3 Jacobian matrix.

3 86 The Open Mechanical Engineering Journal, 2008, Volume 2 Zhou et al. Now, the deired trajectory in workpace i given a X (t) and we need to find the joint angle trajectory (t), correponding to X (t). We can obtain (t) by olving the following invere kinematic equation: + + = J X + ( I J J ) (3) where J + i a peudoinvere matrix, and i a vector of arbitrary joint velocitie projected in the null pace of J. We can reolve the redundancy by pecifying, o a to atify an additional contraint. Fig. (3). A four-ection boom ytem. For a line trajectory to be poured, the end hoe poition are definite beforehand. That i to ay, a erie of trajectory coordinate X i known, the trajectory coordinate X been correponding to the joint angle, and the joint angle can be olved by Equation (3). We utilize MATLAB oftware to calculate the joint angle and the boom trajectory, i hown in Fig. (4). In thi tudy, the motion poture planning of the boom mechanim during concrete pouring proce i defined, within ingularity avoidance. We aved five joint angle ( ) with repect to every tep (X) a data file, which will be ued in the next phae. In ADAMS, thee joint angle are imported and create five Spline (The Spline i a command of ADAMS and a twoorder Spline i ued in thi tudy). Thee Spline are applied to five revolution MOTION to control the boom movement. A hown in Fig. (5), the end hoe can move along the deired line. We alo produced five Spline by uing Meaure function on the joint (one rotational joint on the turn-table and four tranlational joint on the hydraulic cylinder). Thee Spline were exported into two column data file and will be imported into Matlab for co-imulation. DYNAMIC ANALYSIS USING ADAMS In order to verify the influence of new automatic pray ytem on the boom, we performed a dynamic analyi uing ADAMS and Simulink. The co-imulation method ued here i implemented by uing ADAMS/Control oftware for imulation of the mechanical ytem and MATLAB/Simulink for imulation of the hydraulic ytem. Generally, MATLAB/Simulink i alo ued to model the control concept, which can drive the dynamic characteritic of a ytem baed on enor feedback, while ADAMS i ued to model mechanical part of the ytem, that are influenced by their geometric tructure a well a external load and force impoed on them. The mechanical part of concrete boom ytem are hown in Fig. (5) and the hydraulic control ytem i hown in Fig. (6) [21-24]. 8 7 ) m ( t h g i e H Height (m) Length (m) Fig. (4). The movement poture of the boom ytem for a traight-line trajectory.

4 Ditribution Boom Sytem of Truck-Mounted Concrete Pump The Open Mechanical Engineering Journal, 2008, Volume 2 87 boom arm do not belong to geometrically imple tructure in a ene. It will produce wrong reult if we ue a box part to take the place of the boom arm. So, we have to create a flexible boom arm uing ANSYS. In ADAMS, flexible bodie are defined by importing the modal data, calculated by an external finite element program. A pecial data file (MNF file) i ued to tranfer frequency and amplitude data for a elected number of vibration mode, from a finite element code to ADAMS program. Craig Bampton mode, which are required for defining contraint connection to flexible bodie, are tranferred from the finite element code by defining mater node. For each mater node, contraint mode information i tored in the MNF file. Fig. (5). Kinematic imulation in ADAMS. In Fig. (6) there are four PitonRod and one Rotor. They were controlled by the five Spline data file. One drawback of the ADAMS program i that all component are aumed to be rigid. In the ADAMS program, tool to model component flexibility, exit only for geometrically imple tructure. To account for the flexibility of a geometrically complex component, ADAMS relie on the data tranferred from finite-element program uch a ANSYS. The ANSYS-ADAMS Interface i a tool provided by ANSYS by which the data can be tranferred from the ANSYS program to the ADAMS program [25-29]. To analyze the boom trength, we need to build flexible arm of the boom mechanim in ADAMS. Obviouly, the CREATING FLEXIBLE BODY Since the firt arm of the boom ytem i ubjected to the bigget load, we created a flexible arm in ANSYS to ubtitute the firt rigid arm for co-imulation in ADMAS. Becaue a flexible body analyi require a high performance on the PC, we only ued one flexible arm, the firt arm, i.e. in thi tudy. Element Type The element type will affect on the computation time and reult accuracy. For the boom ytem, the tructure i not very complicated o, we elect two olid type, SOLID45 and SOLID92 in ANSYS program, for different region of the firt arm of the boom ytem. PitonRod 1 Workpace 1 e1 Kr1 Gain 1 K T*T. 2+2*C*T+1 ServoValve 1 Q1 Kc 1 Tc 1 * Tc * Cc 1 *Tc 1+1 HydraulicCylinder 1 V1 1 X1 Integrator 1 Angle 1 PitonRod 2 Workpace 2 e2 Kr2 Gain 2 K T*T. 2+2*C*T+1 ServoValve 2 Q2 Kc 2 Tc 2 * Tc * Cc 2 *Tc 2+1 HydraulicCylinder 2 V2 1 X2 Integrator 2 Angle 2 PitonRod 3 Workpace 3 e3 Kr3 Gain 3 K T*T. 2+2*C*T+1 ServoValve 3 Q3 Kc 3 Tc 3 * Tc * Cc 3 *Tc 3+1 HydraulicCylinder 3 V3 1 Integrator 3 X3 Angle 3 PitonRod 4 Workpace 4 e4 Kr4 Gain 4 K T*T. 2+2*C*T+1 ServoValve 4 Q4 Kc 4 Tc 4 * Tc * Cc 4 *Tc 4+1 HydraulicCylinder 4 V4 1 X4 Integrator 4 Angle 4 Rotor Workpace 5 e5 Kr5 Gain 5 K T*T. 2+2*C*T+1 ServoValve 5 Q5 Kc 5 Tc 5 * Tc * Cc 5 *Tc 5+1 HydraulicMoto _ 1 _ Integrator 5 Angle 5 adam _ ub Fig. (6). The control cheme of Co-imulation in ADAMS and Matlab/Simulink.

5 88 The Open Mechanical Engineering Journal, 2008, Volume 2 Zhou et al. Material Property The boom of truck-mounted concrete pump i made of fine grained tructural teel, which i a kind of high trength teel. It material property i a follow, elatic modulu Pa, Poion ratio 0.3, denity kg/m 3 and tenile trength 800MPa. (including the load applied on five mater node in every time tep) i exported from ADAMS. Then the data file will be imported into ANSYS, to perform a tranient dynamic analyi to check the tre and train on the firt arm and will afford information to modify or optimize the tructure of the boom arm. Mater Node The mater node i the joint between the boom and other part, uch a hydraulic cylinder and the turntable. According to the contraint, load and driving force on the firt arm, five mater node are defined. Thee mater node ue MASS21 element with a tiny real contant and a huge elatic modulu. Mehing The firt arm i divided into nine part with workplane. The regular part are mehed with SOLID45 element, while the other are mehed with SOLID92 element. Thi method reduce element number dramatically and certainly ave computation time. The mehed model of the firt arm i hown in Fig. (7). The five pink area are rigid coupled area. Finally, uing ANSYS interface for ADAMS program, the firt arm model i exported into a MNF file. Fig. (7). Finite element model of the firt arm of the boom ytem. FLEXIBLE BODY SIMULATION The flexible arm i created in ADAMS by the neutral file imported from ANSYS, to replace the firt rigid arm. The boom movement i imulated again under the previou control SPLINE on the revolution MOTION, hown in Fig. (8). There i a light fluctuation on the end hoe trajectory ince the firt arm i replaced with a flexible body and it ha an inevitable vibration. In order to analyze accurately tre and train on the firt arm during automatically praying concrete, a load tep file Fig. (8). Kinematic imulation of the boom ytem with the flexible arm (the firt arm) in ADAMS. TRANSIENT DYNAMIC ANALYSIS IN ANSYS There are two method to ue the load file in ANSYS. One i to elect the load on the arm in the mot dangerou ituation and then to perform a tatic analyi and obtain the tre and train. Another i to carry on a tranient dynamic analyi with the load changed in tep, and then to predict the time hitory of tre and train. The former method i impractical becaue in a ene it i difficult to elect the mot dangerou ituation. So in thi paper, the latter method i applied to proce the load tep. In order to reduce the calculation, only the firt fifty load tep are imported into ANSYS and the load on five mater node are applied to five rotational joint, repectively. After the tranient dynamic analyi, we can view the reult in ANSYS potproceor. The relationhip between tre and timehitory i hown in Fig. (9) and equivalent tre on the econd load tep i hown in Fig. (10). In the potproceor of ANSYS, we find that the tre in the joint area i higher than that of other region with repect to every load tep. We elect a node in the high tre area and track the tre time-hitory. The reult i hown in Fig. (9). It how that in the beginning, the tre increae rapidly and reache the maximum at the econd tep, about 640MPa, and then gradually fall down and at the twentieth tep the tre tend to be teady, about 350MPa. The firtorder vibration frequency of the arm i 4.9Hz. The previou experiment tudie [8, 30] reported that the vibration frequency i 4.69Hz. According to the tre time-hitory, we load the equivalent tre on the firt arm at the econd tep, one of the mot dangerou ituation, a hown in Fig. (10). Fig. (10) we can find that the tre in mot area varie from 200MPa to 250MPa, except the joint area. The reference [30] alo reported the imilar tre value by experimental meaurement. Conidering that the arm model ha no fillet,

6 Ditribution Boom Sytem of Truck-Mounted Concrete Pump The Open Mechanical Engineering Journal, 2008, Volume Node tre (10 6 Pa) Node tre (10 6 Pa) Load tep (n) Fig. (9). The time-hitory curve of tre for a node on the flexible arm. Fig. (10). The equivalent tre ditribution of the firt arm in ANSYS. the number of imulation tep i le and in the beginning of loading, the arm motion acceleration i alo high, o, the maximum tre at the joint region hould be lower in the real arm. Therefore, the trength of the firt boom arm i within a permiible range. AUTOMATIC SPRAY SIMULATION Virtual reality i a technology, which allow a uer to interact with a model in a computer-imulated environment [31-36]. It i the reult of the combination of human imagination and electronic technologie. It provide people a ueful tool to tudy and examine a model or ytem before it i actually manufactured [37-39]. In order to verify the automatic pray ytem, we utilized virtual reality technology to imulate it in a three-dimenional environment. The imulation program wa developed with Viual C++ and OpenGL. The model of a truck-mounted concrete pump and it ditribution boom ytem wa deigned in 3DSMAX, and then wa imported into the program [40-42]. The final model

7 90 The Open Mechanical Engineering Journal, 2008, Volume 2 Zhou et al. of the truck-mounted concrete pump and it boom ytem are hown in Fig. (11). The object of thi imulation i to imitate the work proce of the concrete boom ytem. The default etting of thi ytem i a linear pray. In the firt tep, we can move the end hoe to a pecified poition through five croll bar in the left control panel in Fig. (12) and pre down the Record button. Secondly, we can move the end hoe to another end of the wall and record it. Now the control module ha recorded two key point of the trajectory line. After we preed the Pour button, the whole ytem begin to pour concrete automatically along the trajectory line. In Fig. (12), the red thin line i the predefined trajectory and the blue thick line i the actual trajectory. Thi Fig. (11). Truck-mounted concrete pump and it boom ytem in virtual reality environment. Fig. (12). Automatic pray ytem imulation in virtual reality environment.

8 Ditribution Boom Sytem of Truck-Mounted Concrete Pump The Open Mechanical Engineering Journal, 2008, Volume 2 91 imulation ytem can verify whether any interference occur between boom ection and whether the boom movement i mooth. The imulation reult how that the ytem can pour concrete on a long narrow field automatically, and the boom movement i mooth. CONCLUSIONS The automatic pray ytem of the ditribution boom ytem of the truck-mounted concrete pump ha been tudied and the kinematic redundancy i olved. A co-imulation method wa ued to check the dynamic repone of concrete pouring proce of the automatic pray ytem. Virtual reality technology wa ued to imulate the automatic pray proce. Baed on the dynamic load obtained from abovementioned analye, the finite element method wa ued to analyze the tructural trength of the boom ytem. Thee ytemic numerical imulation method will provide a trong aitance for the development of new concrete boom ytem. 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9 92 The Open Mechanical Engineering Journal, 2008, Volume 2 Zhou et al. [41] G.Z. Fei, L. Qiao. Viual C advanced program technique-- OpenGL part. Beijing: China Railway Publihing Houe, [42] H.Y.K. Lau and K.L. Mak, A virtual deign platform for interactive product deign and viualization, Journal of Material Proceing Technology, Vol. 39, pp , Nov Received: November 21, 2007 Revied: April 23, 2008 Accepted: June 11, 2008 Zhou et al.; Licenee Bentham Open. Thi i an open acce article licened under the term of the Creative Common Attribution Non-Commercial Licene ( which permit unretricted, non-commercial ue, ditribution and reproduction in any medium, provided the work i properly cited.