This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot’s end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H∞ tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to verify the feasibility of the proposed parallel mechanism robot driven by three vertical pneumatic servo actuators, a full-scale test rig of the proposed parallel mechanism pneumatic robot is set up. Thus, simulations and experiments for different complex 3D motion profiles of the robot end-effector can be successfully achieved. The desired, the actual and the calculated 3D position of the end-effector can be compared in the complex 3D motion control.
References
[1]
Brogardh, T. Present and future robot control development—An industrial perspective. Ann. Rev. Control 2007, 31, 69–79, doi:10.1016/j.arcontrol.2007.01.002.
[2]
Wang, J.; Liu, X.J. Analysis of a novel cylindrical 3-DoF parallel robot. Robot. Auton. Syst 2003, 42, 31–46, doi:10.1016/S0921-8890(02)00296-8.
[3]
Li, Q.; Wu, F.X. Control performance improvement of a parallel robot via the design for control approach. Mechatronics 2004, 14, 947–964, doi:10.1016/j.mechatronics.2004.04.002.
[4]
Laribi, M.A.; Romdhane, L.; Zeghloul, S. Analysis and dimensional synthesis of the DELTA robot for a prescribed workspace. Mech. Mach. Theory 2007, 42, 859–870, doi:10.1016/j.mechmachtheory.2006.06.012.
[5]
Bera, T.K.; Samantarat, A.K.; Karmakar, R. Robust overwhelming control of a hydraulically driven three-degrees-of-freedom parallel manipulator through a simplified fast inverse model. JSCE 2009, 828, 169–184.
[6]
Robertz, S.G.; Halt, L.; Kelkar, S.; Nilsson, K.; Robertsson, A.; Schar, D.; Schiffer, J. Precise Robot Motions Using Dual Motor Control. Proceedings of the 2010 IEEE International Conference on Robotics and Automation, Anchorage, AK, USA, 3–8 May 2010; pp. 5613–5620.
[7]
Uchiyama, T.; Terada, H.; Mitsuya, H. Continuous path control of a 5-DOF parallel-serial hybrid robot. J. Mech. Sci. Technol 2010, 24, 47–50, doi:10.1007/s12206-009-1166-x.
[8]
Chiang, M.-H.; Lin, H.-T.; Hou, C.-L. Development of a stereo vision measurement system for a 3d three-axial pneumatic parallel mechanism robot arm. Sensors 2011, 11, 2257–2281, doi:10.3390/s110202257. 22319408
[9]
Drakunov, S.; Hanchin, G.D.; Su, W.C.; ？zgüner, ü. Nonlinear control of rodless pneumatic servo actuator, or sliding modes versus Coulomb friction. Automatica 1997, 33, 1401–1408, doi:10.1016/S0005-1098(97)00015-0.
[10]
Varseveld, R.B.V.; Bone, G.M. Accurate position control of a pneumatic actuator using on/off solenoid valves. IEEE/ASME Trans. Mechatron 1997, 2, 195–204, doi:10.1109/3516.622972.
[11]
Wang, J.; Pu, J.; Moore, P.R.; Zhang, Z. Modeling study and servo-control of air motor systems. Int. J. Control 1998, 71, 459–476, doi:10.1080/002071798221777.
[12]
Wang, J.; Pu, J.; Moore, P.R. A practicable control strategy for servo pneumatic actuator systems. Control Eng. Pract 1999, 7, 1483–1488, doi:10.1016/S0967-0661(99)00115-X.
[13]
Konishi, S.; Nokata, M.; Jeong, O.C.; Kusuda, S.; Sakakibara, T.; Kuwayama, M.; Tsutsumi, H. Pneumatic Micro Hand and Miniaturized Parallel Link Robot for Micro Manipulation Robot System. Proceedings of the 2006 IEEE International Conference in Robotics and Automation, Orlando, FL, USA, 15–19 May 2006; pp. 1036–1041.
[14]
Choi, H.-S.; Han, C.-S.; Lee, K.-Y.; Lee, S.-H. Development of hybrid for construction works with pneumatic actuator. Autom. Constr 2005, 14, 452–459, doi:10.1016/j.autcon.2004.09.008.
[15]
Chiang, M.-H. Development of X–Y servo pneumatic-piezoelectric hybrid actuators for position control with high response, large stroke and nanometer accuracy. Sensors 2010, 10, 2675–2693, doi:10.3390/s100402675. 22319266
[16]
Ning, S.; Bone, G.M. Development of a Nonlinear Dynamic Model for a Servo Pneumatic Positioning System. Proceedings of the IEEE International Conference on Mechatronics & Automation, Niagara Falls, ON, Canada, 29 July–1 August 2005; pp. 43–48.
[17]
Rao, Z.; Bone, G.M. Nonlinear modeling and control of servo pneumatic actuators. IEEE Trans. Control Syst. Technol 2008, 16, 562–569, doi:10.1109/TCST.2007.912127.
[18]
Cai, L.; Huang, W. Fourier series based learning control and application to positioning table. Robot. Auton. Syst 2000, 32, 89–100, doi:10.1016/S0921-8890(99)00111-6.
[19]
Shu, N.; Bone, G.M. High Steady-State Accuracy Pneumatic Servo Positioning System with PVA/PV Control and Friction Compensation. Proceedings of the 2002 IEEE International Conference on Robotics & Automation, Washington, DC, USA, 11–15 May 2002; pp. 2824–2829.
Tsai, Y.C.; Huang, A.C. Multiple-surface sliding controller design for pneumatic servo systems. Mechatronics 2007, 18, 506–512.
[22]
Bone, G.M.; Ning, S. Experimental comparison of position tracking control algorithms for pneumatic cylinder actuators. IEEE/ASME Trans. Mechatron 2007, 12, 557–561, doi:10.1109/TMECH.2007.905718.
[23]
Huang, A.C.; Kuo, Y.S. Sliding control of nonlinear systems containing time-varying uncertainties with unknown bounds. Int. J. Control 1999, 74, 252–264.
[24]
Tsai, Y.-C.; Huang, A.-C. FAT-based adaptive control for pneumatic servo systems with mismatched uncertainties. Mech. Syst. Signal Process 2008, 22, 1263–1273, doi:10.1016/j.ymssp.2007.10.011.
[25]
Chiang, M.-H.; Lee, L.-W.; Kuo, C.-F.; Chen, Y.-N. A H∞ tracking-based adaptive sliding-mode controller for nonlinear pneumatic path tracking systems via a functional approximation approach. J. Chin. Soc. Mech. Eng 2009, 24, 507–515.
[26]
Craig, J.J. Introduction to Robotics; Pearson Education Inc.: Upper Saddle River, NJ, USA, 2005.
