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Energy Modeling and Power Measurement for Mobile Robots

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Energy Modeling and Power Measurement for Mobile Robots energies Article Energy Modeling and Power Measurement for Mobile Robots Linfei Hou 1, Liang Zhang 1,* and Jongwon Kim 2 1 School of Mechanical, Electrical and Information Engineering, Shandong University (Weihai), Weihai 264209, China; [email protected] 2 Department of Electromechanical Convergence Engineering, Korea University of Technology and Education, Cheonan 31253, Korea; [email protected] * Correspondence: [email protected]; Tel.: +86-130-6118-7255 Received: 20 October 2018; Accepted: 21 December 2018; Published: 22 December 2018 Abstract: To improve the energy efficiency of a mobile robot, a novel energy modeling method for mobile robots is proposed in this paper. The robot can calculate and predict energy consumption through the energy model, which provides a guide to facilitate energy-efficient strategies. The energy consumption of the mobile robot is first modeled by considering three major factors: the sensor system, control system, and motion system. The relationship between the three systems is elaborated by formulas. Then, the model is utilized and experimentally tested in a four-wheeled Mecanum mobile robot. Furthermore, the power measurement methods are discussed. The energy consumption of the sensor system and control system was at the milliwatt level, and a Monsoon power monitor was used to accurately measure the electrical power of the systems. The experimental results showed that the proposed energy model can be used to predict the energy consumption of the robot movement processes in addition to being able to efficiently support the analysis of the energy consumption characteristics of mobile robots. Keywords: robot energy modeling; energy measurements; energy consumption; mobile robot 1. Introduction Robotics is undergoing a major transformation in scope and dimension. From a largely dominant industrial focus, robotics is rapidly expanding into human environments and is vigorously engaged in new challenges [1,2]. In order to work better in complex situations, these robots are mobile and driven by batteries [3]. Mobile robots are widely used in modern manufacturing systems, while their use is also extending into human daily life [4]. Mobile robots are limited by heavy and expensive batteries, which makes energy efficiency a key constraint on robot performance. Thus, modeling and managing energy consumption is of vital importance to predict the lifetime and range of autonomous platforms. It is of great significance to study the energy consumption of mobile robots [5,6]. The energy problem of mobile robots has been paid more attention in order to meet requirements of reducing energy consumption. The energy consumption modeling of mobile robots [7] based on mathematical formulas can be more scientific to study the influence of operation states on energy consumption, which provides a guide to facilitate energy-efficient strategies [8]. Firstly, the robot itself can clearly understand the energy required for the robot’s motion and the specific energy consumption of each part; therefore, the energy consumption can be reduced according to different situations and the existing energy support can be estimated. Still, recent publications have adopted very different methods when it comes to the calculation of energy consumption. Many authors have attempted to achieve this through modifications in trajectory planning, control, or mechanical design [9–13]. Energies 2019, 12, 27; doi:10.3390/en12010027 www.mdpi.com/journal/energies EnergiesEnergies2019 2018, ,12 10,, 27 x FOR PEER REVIEW 2 ofof 1515 A novel method of energy consumption modeling is proposed in this paper. The method involvesA novel dividing method the of energy energy consumption modelingof the robot is proposed into three in parts: this paper. the sensor The method system, involves control dividingsystem, and the energymotion consumption system. The ofblock the robotdiagram into of three the parts:system the is sensorshown system, in Figure control 1. Figure system, 1a andrepresents motion the system. electrical The energy block diagram transmission of the and system Figure is shown1b represents in Figure the1 .signal Figure transmission1a represents during the electricalthe robot’s energy work. transmission and Figure1b represents the signal transmission during the robot’s work. (a) (b) FigureFigure 1. 1.Block Block diagram diagram of of the the system. system. ( (aa)) Electrical Electrical energy energy transmission; transmission; ( b(b)) Signal Signal transmission. transmission. TheThe electrical electrical power power measurement measurement tools tools accurately accurately measure measure the the specific specific electrical electrical power power of of the the threethree parts parts and and then then give give a a complete complete mathematical mathematical formula formula to to summarize summarize the the energy energy consumption consumption of theof the robot robot in various in various situations. situations. ThisThis model model waswas utilized utilized andand experimentallyexperimentally testedtested inin aa four-wheeledfour‐wheeled MecanumMecanum mobilemobile robot.robot. TheseThese typestypes of robots robots can can move move sideways, sideways, turn turn on onthe the spot, spot, and andfollow follow complex complex trajectories trajectories [14]. These [14]. Theserobots robots are capable are capable of easily of easily performing performing tasks tasks in environments in environments with with static static and anddynamic dynamic obstacles obstacles and andnarrow narrow aisles aisles [15]. [The15]. electrical The electrical power power of the sensor of the sensorsystem systemand control and system control was system at the was milliwatt at the milliwattlevel, and level, a Monsoon and a Monsoon power monitor power monitor was used was to used accurately to accurately measure measure the electrical the electrical power power of the of thesystems. systems. The The electrical electrical power power of ofthe the motion motion system system was was at at the the watt watt level, level, and aa RigolRigol DP1308ADP1308A programmableprogrammable direct direct current current (DC) (DC) power power supply supply (RIGOL (RIGOL Technology Technology Co., Co., Ltd., Ltd., Beijing, Beijing, China) China) was was usedused to to measure measure the the motion motion system. system. 2. Related Works 2. Related Works WithWith thethe aimaim ofof energy energy consumption consumption minimizationminimization inin robots,robots, manymany publishedpublished worksworks havehave describeddescribed effective effective methods methods to to achieve achieve this this goal. goal. AnAn energy energy modeling modeling method method by by measuring measuring the the total total power power for for an an industry industry robot robot was was proposed proposed byby Xu Xu et et al. al. [ [8].8]. ThisThis methodmethod avoidsavoids thethe problemproblem ofof directlydirectly measuringmeasuring relevant relevant parameters parameters inside inside the the robot.robot. The The main main content content of of this this method method is is joint joint torque torque modeling, modeling, and and the the parameter parameter estimation estimation is is one one ofof the the most most important important steps steps in in the the process process of of the the torque torque modeling. modeling. VerstratenVerstraten et et al. al. [ 9[9]] studied studied how how well well different different modeling modeling approaches approaches commonly commonly foundfound inin thethe literatureliterature cancan predict the the energy energy consumption consumption of of a ageared geared DC DC motor motor performing performing a dynamic a dynamic task. task. The Theresults results from from their their work work serve serve to toaid aid designers designers in in deciding deciding which which elements elements to to include include in their model,model, whetherwhether their their purpose purpose is is to to compare compare designs designs or or to to obtain obtain an an actual actual estimate estimate of of the the consumed consumed power. power. InIn References References [16 [16,17],,17], energy energy optimization optimization was was investigated investigated by hardwareby hardware replacements. replacements. Using Using low powerlow power hardware hardware can reduce can reduce the overall the overall electrical electrical energy energy consumption consumption of the of robot. the robot. BukataBukata etet al. al. [ 18[18]] studied studied the the energy energy optimization optimization of of industrial industrial robotic robotic cells, cells, which which is is essential essential forfor sustainablesustainable productionproduction inin thethe longlong term. term. AA holisticholistic approachapproach thatthat considersconsiders aa roboticrobotic cellcell asas aa wholewhole robot robot was was proposed proposed in orderin order to minimize to minimize energy energy consumption. consumption. The mathematical The mathematical model, model, which considerswhich considers various robotvarious speeds, robot positions, speeds, positions, power-saving power modes,‐saving and modes, alternative and ordersalternative of operations, orders of canoperations, be transformed can be into transformed a mixed-integer into a linear mixed programming‐integer linear formulation programming that is,formulation however, suitable that is, onlyhowever, for small suitable instances. only for To small optimize instances. complex To robotic optimize cells, complex a hybrid robotic heuristic cells,
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