1、DOI 10.1007/s10033-XXX-XXXX-X 1Chin. J. Mech. Eng.ORIGINAL ARTICLENovel 6-DOF Wearable Exoskeleton Arm with Pneumatic Force-Feedbackfor Bilateral TeleoperationJia-Fan Zhang1, 3 Hai-Lun Fu2 Yi-Ming Dong1 Yu Zhang1 Can-Jun Yang1 Ying Chen1Received June xx, 201x; revised February xx, 201x; accepted Mar
2、ch xx, 201x Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2017Abstract: Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial f
3、orce in China, and a new magnetic drive pump with low flow and high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magnetic drive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT is used to simulate the
4、inner flow field of magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis of velocity and pressu
5、re, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different
6、rotated speeds. In addition, the magnetic drive pumps are tested in a closed testing system. Pressure sensors are set in inlet and outlet of magnetic drive pumps to get the pressure and the head, while Supported by National Natural Science Foundation of China (Grant No. 50305035), National Hi-tech R
7、esearch and Development Program of China(863 Program, Grant No. #), Beijing Municipal Natural Science Foundation of China(Grant No. #), and Zhejiang Provincial Natural Science Foundation of China(Grant Nos. #, #) Jia-Fan Z1 State Key Laboratory of Fluid Power Transmission and Control, Zhejiang Unive
8、rsity, Hangzhou 310027, China2 Zhejiang Province Instituteof Metrology, Hangzhou 310027, China3 National Die slave-robot working in hazardous zone; data transmission between supervisor-master and master-slave through the Internet or Ethernet. In section 2, by using the orthogonal experiment design m
9、ethod, the design foundation of ZJUESA and its optimal, we hybrid fuzzy control system for the force feedback on ZJUESA. Consequently, the force feedback control simulations and experiment results analysis are presented in Section 4 1317.2 Configuration of the Exoskeleton ArmSystemThe master-slave c
10、ontrol is widely employed in the robot manipulation. In most cases, the joystick or the keyboard is the routine input device for the robot master-slave control system. The system presented in this paper is shown in Figure 1. Figure 1 Configuration of the exoskeleton arm systemIn the system the exosk
11、eleton armZJUESA replaces the joystick as the command generator. It is an external structure mechanism, which can be worn by the operator, and can transfer the motions of human upper arm to the slave manipulator position-control-commands through the Internet or Ethernet between the master and slave
12、computers. With this information, the slave manipulator mimics the motion of the operator. At the same time, the force-feedback signals, detected by the 6-axis force/torque sensor on the slave robot arm end effector, are sent back to indicate the pneumatic actuators for the force-feedback on ZJUESA
13、to realize the bilateral teleoperation.Since ZJUESA is designed by following the physiological parameters of the human upper-limb, with such a device the human operator can control the manipulator more comfortably and intuitively than the system with the joystick or the keyboard input.3 Design of th
14、e Exoskeleton ArmWhat we desire is an arm exoskeleton which is capable of following motions of the human upper-limb accurately and supplying the human upper-limb with proper force feedback if needed. In order to achieve an ideal controlling performance, we have to examine the structure of the human
15、upper-limb.3.1 Anatomy of Human Upper-limb3.1.1 One Apple and Two Banana (实词首字母大写 )Recently, various models of the human upper-limb anatomy have been derived. The biomechanical models of the arm that stand for precise anatomical models including muscles, tendons and bones are too complex to be utili
16、zed in mechanical design of an anthropomorphic robot arm. From the view of the mechanism, we should set up a more practicable model for easy and effective realization. Figure 2 introduces the configuration of human upper-limb and its equivalent mechanical model, which is a 7-DOF structure, including
17、 3 degrees of freedom for shoulder (flexion/extension, abduction/adduction and rotation), 1 degree of freedom for elbow (flexion/extension) and 3 degrees of freedom for wrist (flexion/ extension, abduction/adduction and rotation) 18. The details about the motion characteristics of these skeletal joi
18、nts can be obtained in Refs. 18-20. Compared to the mechanical model, the shoulder and wrist can be considered as spherical joints and the elbow as a revolution joint. It is a good approximate model for the human arm, and the base for the design and construction of exoskeleton arm-ZJUESA. 二级标题字号 10
19、磅图中字体为 Times New Roman，字号大小为 8 磅Novel 6-DOF Wearable Exoskeleton Arm with Pneumatic Force-Feedback for Bilateral Teleoperation 3Figure 2 Configuration of human upper limb and its equivalent mechanical model3.2 Mechanism of the Exoskeleton ArmBecause the goal of this device is to follow motions of th
20、e human arm accurately for teleoperation, ZJUESA ought to make the best of motion scope of the human upper-limb and limit it as little as possible. A flexible structure with the same or similar configuration of human upper-limb is an ideal choice. Based on the anatomy of human upper-limb, the joint
21、motion originates from extension or flexion of the muscle and ligament with each other to generate torque around the bones. Compared with the serial mechanism, the movements of the parallel mechanism are driven by the prismatics, which act analogically to the human muscles and ligament. Besides, usi
22、ng the parallel mechanism not only realizes the multi-DOF joint for a compact structure and ligament. Besides, using the parallel mechanism not only realizes the multi-DOF joint for a compact structure of human upper-limb. The 3RPS parallel mechanism is one of the simplest mechanisms. Figure 3 expla
23、ins the principle of the 3RPS parallel mechanism. Kim et al. 11, introduced it into the KIST design. Here we follow this concept. The two revolution degrees of freedom embodied in the 3RPS are for flexion/extension, abduction/adduction at shoulder. Its third translation degree of freedom along z axi
24、s can be used for the dimension adjustment of ZJUESA for different operators. The prismatic joints are embodied by pneumatic actuators, which are deployed to supply force reflective capability. Also displacement sensors are located along with the pneumatic actuators and the ring-shaped joints to mea
25、sure their linear and angular displacements. At elbow, a crank-slide mechanism composed of a cylinder and links is utilized for flexion/extension. At wrist, since the abduction/ adduction movement is so limited and can be indirectly reached by combination of the other joints, we simplify the configu
26、ration by ignoring the effect of this movement. As shown in Figure 4, the additional ring is the same as that at shoulder for the elbow rotation. Thus our exoskeleton arm-ZJUESA has 6 degrees of freedom totally. Figure 3 3RPS parallel mechanismFigure 4 Prototype of the exoskeleton arm-ZJUESA 3.3 Opt
27、imization Design of ZJUESAAs nentioned above, the best design is to make the workspace of ZJUESA as fully cover the scope of the human upper-limb motion as possible. We employ the 3RPS parallel mechanism for the shoulder, whose workspace mainly influences the workspace of ZJUESA. The optimal design
28、of 3RPS parallel mechanism for the shoulder is the key point of ZJUESA optimal design. However, it is a designing problem with multi-factors, saying the displacement of the prismatics (factor A), circumradius ratio of the upper and lower platforms (factor B), initial length of the prismatics (factor
29、 C), and their coupling parameters (factor A*B, A*C and B*C) (Table 1) and multi-targets, namely, its workspace, weight, size. So, we use the orthogonal experiment design method with foregoing 6 key factors 21 and Eq. (1) gives the expression of the optimal target function of this problem: , (1)0, x
30、rQFLR另行排的数学式必须居中，单倍行距，段后回车换行 1 次页码文字周围的图文框宽 1.1 cm，高 0.4 cm，相对于“页面”水平距离 18 cm，相对于 “段落”垂直距离0.4 cmJia-Fan Zhang et al.4where L0 is the initial length of the prismatics, R is the circumradius of the lower base in 3RPS mechanism, r is the circumradius of the upper base in 3RPS mechanism, is the expected
31、 reachable angle around axis, and is the xreachable angle around axis.Table 1 Factors and their levels mm Level rank A B C A*B A*C B*C1 60 0.5 150 2 80 0.438 160 3 100 0.389 170 4 180 The orthogonal experiment design is outlined because of the ease with which levels can be allocated and its efficien
32、cy. The concept of orthogonal experiment design is discussed in Ref. 21 to obtain parameters optimization, finding the setting for each of a number of input parameters that optimizes the output(s) of the design. Orthogonal experiment design allows a decrease in the number of experiments performed wi
33、th only slightly less accuracy than full factor testing. The orthogonal experiment design concept can be used for any complicated system being investigated, regardless of the nature of the system. During the optimization, all variables, even continuous ones, are thought of discrete “levels”. In an o
34、rthogonal experiment design, the levels of each factors are allocated by using an orthogonal array22. By discretizing variables in this way, a design of experiments is advantageous in that it can reduce the number of combinations and is resistant to noise and conclusions valid over the entire region
35、 spanned by the control factors and their setting. Table 2 describes an orthogonal experiment design array for 6 key factors 23. In this array the first column implies the number of the experiments and factors A, B, C, A*B, A*B and B*C are arbitrarily assigned to columns respectively. From Table 2,
36、36 trials of experiments are needed, with the level of each factor for each trial-run indicated in the array. The elements represent the levels of each factors. The vertical columns represent the experimental factors to be studied using that array. Each of the columns contains several assignments at
37、 each level for the corresponding factors. The levels of the latter three factors are dependent on those of the former three factors. The elements of the column IV, namely factor A*B, are determined by the elements in the columns I, II, and elements of column V, factor A*C, has the relationship with
38、 the elements of columns I, III, and the column VI, factor B*C, lies on the columns II, III.Table 2 Orthogonal experiment design array L36 for 6 key factorsExperiment No. A B C A*B A*C B*C Result Q1 1 1 1 1 1 1 Y12 1 1 2 1 2 2 Y23 1 1 3 1 3 3 Y34 1 1 4 1 4 4 Y45 1 2 1 2 1 5 Y56 1 2 2 2 2 6 Y6 33 3 3
39、 1 9 9 9 Y3334 3 3 2 9 10 10 Y3435 3 3 3 9 11 11 Y3536 3 3 4 9 12 12 Y36The relation between column IV and columns I, II is that: if level of A is n and level of B is m, the level of A*B is 3(n1)+m, where n=1, 2, 3 and m=1, 2, 3. All the cases can be expressed as follows:(1, 1) 1 (1, 2) 2 (1, 3) 3;(
40、2, 1) 4 (2, 2) 5 (2, 3) 6;(3, 1) 7 (3, 2) 8 (3, 3) 9.The first element in the bracket represents the corresponding level of factor A in Table 1 and the latter means the corresponding level of the factor B. Factor A*B .Likewise, the relation between column V and columns I, III is (1, 1) 1 (1, 2) 2 (1
41、, 3) 3 (1, 4) 4;(2, 1) 5 (2, 2) 6 (2, 3) 7 (2, 4) 8;(3, 1) 9 (3, 2) 10 (3, 3) 11 (3, 4) 12.Also the relation between column VI and columns II, III is(1, 1) 1 (1, 2) 2 (1, 3) 3 (1, 4) 4;(2, 1) 5 (2, 2) 6 (2, 3) 7 (2, 4) 8;(3, 1) 9 (3, 2) 10 (3, 3) 11 (3, 4) 12.The optimal design is carried out accord
42、ing to the first three columns: 1212 1235* 6/91/000 ,1/0ABCI YI Y (2)Novel 6-DOF Wearable Exoskeleton Arm with Pneumatic Force-Feedback for Bilateral Teleoperation 5, (3)maxiniijijKIIwhere i=A, B, C, A*B, A*C, B*C; j is the number of i rank.By Eqs. (2), (3) and the kinematics calculation of the 3RPS
43、 parallel mechanism 2435, the relationship between the target Q and each factor can be obtained, as shown in Figure 5. Figure 5 Relation between levels of factors and QAccording to the plots in Figure 5, we can get the superiority and the degree of the influence (sensitivity) of each design factor.
44、The factor with bigger extreme difference Ki, as expressed in Eq. (3) has more influence on Q. In this case, it can be concluded that the sensitivity of the factors A*B and A*C are high and factors B*C and C have weak influence, since KA*B and KA*C are much bigger than KB*C and KC. And the set A3B1,
45、 A2C1, A2, B1, C1, B1C1 are the best combination of each factor levels. But there is a conflict with former 3 items in such a set. As their Ki have little differences between each other, the middle course is chosen. After compromising, we take the level 2 of factor A, the level 1 of factor B and the
46、 level 1 of factor C, namely d80 mm, r/R0.5, L0150 mm 32.It is interesting to know how good the results derived from the above 36 trials are, when compared with all other possible combinations. Because of its mutual balance of orthogonal arrays, this performance ratio can be guaranteed by the theore
47、m in non-parametric statistics 13. It predicts that this optimization is better than 97.29% of alternatives.Combined with the kinematics and dynamics simulation of the 3RPS parallel mechanism and ZJUESA with chosen design parameters by ADAMS, we perform the optimal design. Table 3 indicates the join
48、t range and joint torque of each joint on ZJUESA. It is apparent that ZJUESA can almost cover the workspace of human upper-limb well so that it can follow the motion of human operation upper-limb with little constrain, as shown in Figure 6. Table 3 Joint ranges and joint torques for each joint on ZJ
49、UESAJoint on ZJUESA Joint range /()Joint torque T/(Nm)Joint density m / (kgm3)Flexion/extension(shoulder) 6060 36 Abduction/adduction 5060 36 Rotation(shoulder) 2090 18 Flexion/extension(elbow) 090 28 Rotation(wrist) 2090 13 Flexion/extension(wrist) 060 28 Abduction/ adduction(wrist) Figure 6 Motion of exoskeleton
