[机械模具数控自动化专业毕业设计外文文献及翻译]【期刊】研究移动机制的楼梯爬墙机器人清洗-平移运动机制和回转运动

ORIGINAL ARTICLEStudy on mobile mechanism of a climbing robot for stair cleaning:a translational locomotion mechanism and turning motionTakahisa KakudouKeigo WatanabeIsaku NagaiReceived: 31 March 2012 / Accepted: 23 October 2012 / Published online: 16 November 2012C211 ISAROB 2012Abstract In human living environments, it is often the casethat the cleaning area is three-dimensional space such as ahigh-rise building. An autonomous cleaning robot is proposedso as to move on all floors including stairs in a building. Whena robot cleans in three-dimensional space, it needs to turn fordirection in addition to climb down stairs. The proposed robotselects movement using legs or wheels depending on stairs orflat surfaces. In this paper, a mobile mechanism and a controlmethod are described for translational locomotion. Thetranslational mechanism is based on using two-wheel-drivetype omni-directional mobile mechanism. To recognize astair using the position-sensitive detector, the robot shiftsfrom translational locomotion to climbing down motion oredge-following motion. It is shown that the proposed robotturns to face a stair with the accuracy of 5C176.Keywords Cleaning robot C1 Climbing robot C1 Stair1 IntroductionRecently, various robots have been developed to supportand execute humans work in various fields. One of suchrobots is the autonomous cleaning robot 1. The automa-tion of cleaning by robots reduces labors and saves energyfor a cleaning task, so that there is an increasing need for itin large areas such as stations and airports.In human living environments, it is often the case that thecleaning area is a three-dimensional space such as a high-rise building. Considering cleaning in a three-dimensionalspace, the cleaning area includes the steps of stairs whichlead from one level of a building to another. However, manyof cleaning robots are not considered to move on placesbetween floors. Tajima et al. 2, 3, have developed arobotic system in which the cleaning robot cooperated withthe elevator to clean floors in a high-rise building. However,this system did not consider the cleaning of stairs. As aresult, a cleaning robot itself needs the ability to move onstairs for cleaning in a three-dimensional space. Also, theseveral types of climbing robots using crawlers, wheels andlegs were proposed to move on stairs 46. Those robotswere developed to move on stairs only for improvingtransfer performance of them in uneven surfaces andtransporting people or objects. Therefore, a climbing robotfor cleaning in a three-dimensional space needs to be able toturn itself and keep posture level on the tread board of stairs,as well as moving on stairs.The objective of this study is to develop a climbing robotthat can move on all floors including stairs in a building forautonomous cleaning in a three-dimensional space. Aclimbing robot has been already proposed, where itsstructure was divided into two mechanisms for climbingdown stairs and translational movement 7, 8. In this paper,a mobile mechanism and a control method are described fortranslational locomotion. The operational check of thetranslational mechanism was conducted by facing the robotto the edge of stairs using the position-sensitive detector(PSD).This work was presented in part at the 17th International Symposiumon Artificial Life and Robotics, Oita, Japan, January 1921, 2012.T. Kakudou (&) C1 K. Watanabe C1 I. NagaiDepartment of Intelligent Mechanical Systems, Graduate Schoolof Natural Sciences and Technology, Okayama University,3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japane-mail: t.kakudouusm.sys.okayama-u.ac.jpK. Watanabee-mail: watanabesys.okayama-u.ac.jpI. Nagaie-mail: insys.okayama-u.ac.jp123Artif Life Robotics (2013) 17:400404DOI 10.1007/s10015-012-0071-zThe paper is organized as follows. The concept of thepresent climbing robot is described in Sect. 2. Section 3gives the mobile mechanism for translational locomotion. Inparticular, its mobile mechanism and controller designs aredescribed in detail. The locomotion of the robot on stairs,consisting of cleaning and shifting motion, is explained inSect. 4. Section 5 presents the way of recognizing a stairusing PSDs, together with showing some experimentalresults. Finally, some conclusions are given in Sect. 6.2 Concept of climbing robotIn this study, a climbing robot which can move on stairs isdeveloped to expand the range of moving for the cleaningrobot. The target stair is located in indoor environments andthe shape of its step is rectangular. A climbing robot climbsdown stairs, because the efficient cleaning is to clean fromthe upper floor to the lower floor. In addition, a climbingrobot for cleaning stairs needs to be able to turn for directionand keep posture level on the tread board of stairs, as well asclimb down stairs. Figure 1 shows the proposed climbingrobot whose structure is divided into two mechanisms forclimbing down stairs and translational locomotion. Thisrobot climbs down each step of stairs by its shape which is arectangular solid to fit the shape of step. The L-shaped legswhich are attached on the both sides of a body are used as aclimbing mechanism. The proposed robot climbs downstairs by rotating the body so that the top and bottom sidesof the body may be reversed using L-shaped legs with twodegrees-of-freedom. Also, the proposed robot turns fordirection by a translational locomotion mechanism withomni-directional mobility. A translational locomotionmechanism is discussed in detail in Sect. 3.3 Mobile mechanism for translational locomotionIt is assumed that the cleaning robot is used in an indoorenvironment that is flat such as wooden floor or tile floor.The robot performs translational locomotion using wheelsthat have high transfer efficiency. However, the robot maybe limited in motion by its corners colliding with the walland the riser of stairs when turning around, because theshape of the proposed robot is a rectangular solid as shownin previous sections. So omni-directional mobility isadopted to move and turn around keeping a posture.For some of omni-directional mobile mechanisms withwheels, there are mechanisms with omni-wheel, mecanumwheels, etc. Also this mechanism is attached to the top andbottom of the robot, because the robot climbs down stairs byrotating the body so that the upper and lower sides of body maybe reversed. To reduce the robot weight, it is desirable to usethe fewest possible actuators. Therefore, the mobile mecha-nism for translational mobility used an omni-directionalmobile mechanism with two-wheel-drive system in this study.3.1 Mobile mechanism designFigure 2 shows the proposed mechanism for translating onstair treads. The size of the mechanism is as follows: thewidth is 400 mm, the length is 250 mm, and the groundclearance is 20 mm. Its mechanism consists of four ball-casters and two driving wheels that are attached on a cir-cular plate with a joint.Then, its mechanism is equipped with PSDs and encodersas shown in Fig. 3. The PSD as the range sensor is used forthe robot to recognize stairs. Two PSDs are attached on bothends in the front side of the mobile mechanism for transla-tional locomotion. If the origin is set at the rotational axis,the positions of PSD 1 and PSD 2 are xpsd; C0ypsdC0C1andxpsd; ypsdC0C1in an xy coordinate, respectively. On the otherhand, the encoders are used to control the velocity of therobot or measure the angle of the circular plate.3.2 Controller designCleaning robots keep the quality of cleaning constant bycontrolling the velocity of the robot. The velocity of theFig. 1 Outline of climbing robot for cleaning stairs Fig. 2 Overview of translational mechanismArtif Life Robotics (2013) 17:400404 401123robot is controlled using a PD controller with encoders tomeasure the rotation of wheels. Figure 4 shows the blockdiagram of the velocity control. The motors for the wheelcan take states such as, normal rotation, reverse rotation,stop and braking by sending the signal from the micro-computer SH7125 through a motor driver.4 Locomotion on stairsThe locomotion of the robot on stairs is assumed to consistof two motions, i.e., the cleaning motion and the shiftingmotion.4.1 Cleaning motionThe locomotion of commonly marketed cleaning robots isclassified into four basic motions such as, parallel, spiral,wall-reflection and wall-following motions. The parallelmotion is one of the more suitable motions for cleaningstairs, because the shape of step is a rectangular form thatmakes a path planning easy to make for cleaning. In thecleaning motion based on such parallel motion, the robotrepeats straight going and 90C176 turn, keeping the posture asshown in Fig. 5a.4.2 Shifting motionWhen the robot shifts from translational locomotion toclimbing down motion or edge-following motion that movesto clean along the edge of stairs, it might fall down stairs dueto its posture. Some ball-casters of the robot fall down stairby design when the posture of the robot is inclined at morethan 10C176 over the edge of stairs. Also it is difficult for therobot to stop when the robot once starts falling in descentstair. Therefore, the robot turns to face the edge of stairwhenever stairs are recognized as shown in Fig. 5b.4.3 Kinematic model motionThe kinematic model of the mechanism for translationallocomotion is given by_x_y_h2435r2sin hcr2sin hcr2cos hcr2cos hcr2dC0r2d2435_hR_hLC20C211where x and y are the position coordinates of the robot, hcis the rotated angle of a circular plate, hRand hLare the(a) (b)PSD 1Body plate Circular platePSD 2yxOcBody plate Circular plateRotational jointConnected partEncoderFig. 3 Design of a variety ofsensors a top view, b lateralviewMotor driverSH-7125 MotorTargetvalueOutputvalueEncoder-+PWM VoltageFig. 4 Block diagram of velocity control(b)(a)Fig. 5 Translational locomotion on stairs a parallel motion to cleanstairs, b turning motion to face stairs402 Artif Life Robotics (2013) 17:400404123rotational angles for the right and left wheels, r is the wheelradius, and 2d is the distance between wheels.5 Stair recognition using PSDThe robot recognizes stairs by discriminating a differencebetween the ground clearance and the rise of stairs using aPSD. The PSD outputs the value that converts a distance toan object into DC voltage. When a PSD value is less thanor equal to a threshold for discriminating stair and floor, therobot recognizes it as a stair, whereas the robot recognizesit as a floor, respectively.The robot turns to face the edge of stairs using twoPSDs. If anyone of PSDs recognizes a stair, the circularplate of the robot is rotated so that a reacted PSD is locatedon the wheel axis. Next the robot turns in direction, so theother PSD recognizes a stair. Finally, the robot stops if bothPSDs recognize stairs.Also, the robot turns as shown in Fig. 6, if the angularvelocities of inner and outer wheels have a relationship intheir turning radii such asvinvoutC12C12C12C12C12C12C12C12RinRoutC12C12C12C12C12C12C12C122where vinand voutare the rotational velocities of the innerand outer wheels, and Rinand Routare the turning radii ofthe inner and outer wheels.5.1 Operational checkWe had conducted an operational check to verify theaccuracy of recognizing stairs using PSDs. The evaluationitem is the posture of the robot when it was turned to facestairs at a constant velocity of 150 mm/s from start angles,where the posture angle exceeded from the edge of stairswas assumed to be positive, whereas one under the edge ofstairs was assumed to be negative. Experimental conditionsare as follows: start angles were assumed to be 15C176,30C176,45C176,60C176 and 75C176 as shown in Fig. 7. A rise is defined as180 mm in this study. A threshold for recognizing a stairwas decided as 80 mm, which is the mid-distance betweenthe rise of step and the ground clearance of the robot.Table 1 shows the posture angles of the robot, in whichthe robot faced the edge of stairs every start angle. Figure 8shows the average and standard deviation (SD) of postureangles every start angle.inRoutRpsdOinvoutvvFig. 6 Kinematic model of turning motionStart angleExceeded angleShortened angleEdgeFig. 7 Experimental conditionTable 1 Posture anglesStart angle (C176) Posture angle (C176)Trials Average SD12 34515 0.4 -0.3 0.5 0.3 -0.2 0.14 0.3330 0.7 0.7 0.5 1.2 1.5 0.92 0.3745 3.0 3.5 3.2 4.0 3.0 3.34 0.3860 4.2 2.0 4.0 1.3 1.7 2.64 1.2175 4.1 3.8 2.5 2.0 2.0 2.88 0.90-10123415 30 45 60 75Postur angle for step degStart angle degFig. 8 Average and SD of posture anglesArtif Life Robotics (2013) 17:400404 4031235.2 ConsiderationIf the posture of the robot is inclined at more than 10C176 tothe edge of stair, anyone of ball-casters in front side fallsdown stair. The margin of error in the posture angle isdefined as 5C176 to shift from translational locomotion toclimbing down motion. As a result, the error in the postureangle was within 5C176, and the largest value of SD was 1.2C176after turning motion to face a stair. A relationship betweenthe angular velocity and the turning radius of the wheel wasvin 0:42vout: This performed with an enough accuracybecause a relationship of them gave a close agreement withvin 0:43voutdefined by Eq. (2) in ideal condition.6 ConclusionA cleaning robot to climb down stairs has been developedfor cleaning a three-dimensional space. In particular,mobile mechanisms and a locomotion control method wereproposed for the robot to clean and climb down stairs. Theoperational check of the robot was conducted for recog-nizing stairs. In the result, it was confirmed that the pro-posed robot was able to recognize a stair with an enoughaccuracy to shift from translational locomotion to climbingdown motion. As future work, a function is improved in thelevel of recognizing a surrounding environment such aswalls or balusters in stairs.References1. 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