11-19 Al-Khwarizmi Engineering Journal,Vol. 11, No. Deflection Analysis of an Elastic Single Link Robotic Manipulator Rafal M. *Department of Automated Manufacturing Engineering **Department of Biomedical Engineering (Received Abstract Robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. In certain applications their use is unavoidable. The increased complexity in modeling and control of such manipulators is offset by desirable performance enhancements in some respects. In this paperthe single- link flexible robotics manipulator designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. There are four subsystems; motion, control, accelerometer and robotics manipulator is the base servomotor. It rotates a hub with the link on it and measure the tip deflection. the deflection was measured for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . During each of the above cases I rotated the base servo motor at card based on ATMEGA640 microcontroller. measured by MMA7631 Accelerometer Then the dataI collected collected from accelerometer and plot it using MATLAB software and compared between theoretical results obtained from MATLAB program that based on Lagrange equation of motion and experimental results and we found the maximum deflection occurred when V=180 deg/sec a Keywords: Flexible Link Manipulator , Industrial robotics , 1. Introduction Robotic manipulators are used widely in dangerous, monotonous, and boring of these robotic manipulators are build and manner to maximize stiffness and to minimize the vibration of the end effectors to achi position accuracy. The design of manipulator is achieved by using heavy material and a bulky design. The existing heavy manipulators are known to be insufficient in te of speed and power consumption with respect to the operating payload [1]. To improve industrial productivity robotics, it is required to increase the operation speed of the link and/or reduce the weight of the links. Due to high speed operation and requirements, a dynamic model that includes the joint and / or link flexibilities is needed. Khwarizmi Engineering Journal,Vol. 11, No. 3, P.P. 11-19 (2015) Deflection Analysis of an Elastic Single Link Robotic Manipulator Rafal M. Khalil* Somer M. Nacy** Department of Automated Manufacturing Engineering/ Al-Khwarizmi College of Engineering Department of Biomedical Engineering/ Al-Khwarizmi College of Engineering/ University of *E-mail:Rafalalazzawi90@gmail.com **E-mail :Somernacy@yahoo.com (Received 22 June 2014; accepted 7 May 2015) Robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. In certain applications their use is unavoidable. The increased ling and control of such manipulators is offset by desirable performance enhancements in some link flexible robotics manipulator was designed and implemented designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. There are four motion, control, accelerometer and gyro and a host computer subsystem. The work principle of single s manipulator is the base servomotor. It rotates a hub with the link on it and measure the tip deflection. the for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . rotated the base servo motor at an angular velocity equals to 90 deg./s using control ATMEGA640 microcontroller. the deflection was measured for the three cases and the deflection measured by MMA7631 Accelerometer and Gyro . This accelerometer controlled by using MEGA Arduino board . from accelerometer and plot it using MATLAB software and compared between theoretical results obtained from MATLAB program that based on Lagrange equation of motion and experimental and we found the maximum deflection occurred when V=180 deg/sec and tip load=59.5 gram anipulator , Industrial robotics , Robotics Manipulator ,Beam Deflection widely to help boring jobs. Most build and in a to minimize the vibration of the end effectors to achieve good position accuracy. The design of high stiffness is achieved by using heavy material existing heavy and rigid manipulators are known to be insufficient in terms with respect to improve industrial productivity of the increase the operation reduce the weight of the to high speed operation and lightweight dynamic model that includes the is needed. The Link flexibility is a consequence of the lightweight structure in manipulator arms that are modeled and designed to operate at high speeds with low inertia. Compared conventional heavy and bulky robots weight robot, by introducing flexibility on the mechanical system of robots, it has a great advantages of larger work volume, and lower cost, payload-to-manipulator-weight ratio, lower energy consumption, smaller actuators, better transportability, better maneuver ability end of these advantages its reduced inertia [2]. These great disadvantage obtained by introducing joint and / or link robotics mechanical system, vibration due to low stiffness. If cannot be solved, then the Al-Khwarizmi Engineering Journal (2015) Deflection Analysis of an Elastic Single Link Robotic Manipulator Khwarizmi College of Engineering/ University of Baghdad University of Baghdad Robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. In certain applications their use is unavoidable. The increased ling and control of such manipulators is offset by desirable performance enhancements in some designed and implemented from Perspex and designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. There are four gyro and a host computer subsystem. The work principle of single-link s manipulator is the base servomotor. It rotates a hub with the link on it and measure the tip deflection. the for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . equals to 90 deg./s using control for the three cases and the deflection by using MEGA Arduino board . from accelerometer and plot it using MATLAB software and compared between theoretical results obtained from MATLAB program that based on Lagrange equation of motion and experimental nd tip load=59.5 gram. Beam Deflection. Link flexibility is a consequence of the in manipulator arms that are operate at high operation speeds with low inertia. Compared between the conventional heavy and bulky robots and light by introducing joints and /or link the mechanical system of robots, it advantages of higher operation speed, and lower cost, greater weight ratio, lower smaller actuators, better better maneuver ability and at the end of these advantages its safer operation due to disadvantage obtained by and / or link flexibilities to system, that system has high vibration due to low stiffness. If that problem the mechanical system of Rafal M. Khalil the robot will not been favored in industries will affect the repeatability and accuracy of end point of manipulator in response to input commands. To overcome this problem, an accurate dynamic model of the manipulator characterize with joint and/or link to be developed. This is a first step modeling and designing an efficient control strategies for these manipulators [3]. Before study of flexible manipulator construction materials must be focused on efficient actuation and sensing technologies , and simple and effective controller designs. Flexible robot manipulators are in use in some extent in space applications. This is because of the weight resurrection for a spacecraft ,Other potential areas of application are manipulation in nuclear and other hazardous environment , car painting, manufacturing of electronic hardware and food industry[4]. Cannon and Schmitz [5], studied single flexible manipulators shown in Fig.1 Lagrange’s equation and the assumed mode method for modeling the single link manipulator and the vibration is controlled by measuring the position and using strain gauges have to be very useful for achieving good Fig. 1. Flexible Link Manipulator. Nagarajan and Turcic [6], derived motion using Lagrange’s equation for elastic mechanism systems. The elastic links are modeled using the finite element method. Both rigid body degrees of freedom and the elastic degrees of freedom are considered as generalized coordinates in the derivation. Choi et al. [7] ,”addressed the control dynamic modeling of a single manipulator fabricated from composite laminates (non- metallic) and compared the results with that of aluminum. They have shown that the manipulator fabricated from composite laminates has superior performance characteristics such as Al-Khwarizmi Engineering Journal, Vol. 11, No. 12 industries. This accuracy of the in response to input overcome this problem, an accurate manipulator that can flexibility has to be developed. This is a first step towards designing an efficient controlling for these manipulators [3]. Before study of flexible manipulator the must be focused on , actuation and sensing technologies , and simple and effective controller designs. Flexible are in use in some extent in space applications. This is because of the weight resurrection for a spacecraft ,Other potential areas are manipulation in nuclear and other hazardous environment , car/vehicle painting, manufacturing of electronic hardware , studied single-link shown in Fig.1 using the Lagrange’s equation and the assumed mode method for modeling the single link manipulator s controlled by measuring the ave been found good performance. Flexible Link Manipulator. [1] derived Equations of motion using Lagrange’s equation for elastic The elastic links are modeled using the finite element method. Both rigid body degrees of elastic degrees of freedom are considered as generalized coordinates in the control and the dynamic modeling of a single-link flexible manipulator fabricated from composite laminates the results with that of aluminum. They have shown that the manipulator fabricated from composite laminates characteristics such as faster settling time, smaller input torque and smaller overshoot relative to the manipulator fabricated from aluminum Discussed the utilization of composite materials in the construction of a flexible manipulator to provide higher strength and stiffness ratio and larger structural damping than a metallic flexible manipulator . Krishnamurthy et al. [9], model for single-link robotic arms fabricated from orthotropic composite materials. The equations of motion are derived using Hamilton's principle and include the coupling between the rigid body motion and elastic motion results presented for aluminum, steel, graphite/epoxy, and boron/epoxy indicate that the motion-induced vibration is significantly less for the composite robotic arms as well as substantial savings in energy”. So I made our flexible link manipulator from composite material its most preferred because of its light weight and high strength and large structural damping 2. Characteristics of the Physical Arm The schematic of a planar manipulator is shown in Fig. inertial coordinate frame, and coordinate assigned for a flexible link. an d τ represent the hub position, the deflection do in the arm, and the torque applied to respectively. The existing experimental single link flexible manipulator is a 0.5 flexible structure that can plane but it can’t bend the vertical plane. At end of the arm the different load was putted and at the other end was clamped on a rigid hub from Teflon material mounted directly on the haft of a DC servo motor. A torque applied by the DC servo motor rotates the arm in a horizontal plane. The other end of the arm with payload mass attached is free. The beam of the manipulator is made of Perspex Fig. 2. A Planar Single-Link Flexible Manipulator. Khwarizmi Engineering Journal, Vol. 11, No. 3, P.P. 11- 19(2015) faster settling time, smaller input torque and smaller overshoot relative to the manipulator cated from aluminum “. Choi et al.[8] , Discussed the utilization of composite materials in the construction of a flexible manipulator to provide higher strength and stiffness-to-weight ratio and larger structural damping than a metallic [9], “Present a dynamic link robotic arms fabricated from orthotropic composite materials. The equations of motion are derived using Hamilton's principle and include the coupling between the rigid body otion and elastic motion. Computer simulated results presented for aluminum, steel, graphite/epoxy, and boron/epoxy indicate that the induced vibration is significantly less for the composite robotic arms as well as substantial o I made our flexible link manipulator from composite material its most preferred because of its light weight and high strength and large structural damping. Characteristics of the Physical Arm The schematic of a planar single-Link flexible manipulator is shown in Fig. 2, (X0,Y 0) is an inertial coordinate frame, and ( X 1 ,Y 1)is the coordinate assigned for a flexible link. θ,Ψ(x ,t), represent the hub position, the deflection do the torque applied to the hub, The existing experimental single- link flexible manipulator is a 0.5 m long, a flexible structure that can bend in the horizontal the vertical plane. At the the different load was putted and at clamped on a rigid hub made mounted directly on the haft torque applied by the DC servo motor rotates the arm in a horizontal plane. The other end of the arm with payload mass attached is free. manipulator is made of Perspex. Link Flexible Manipulator. Rafal M. Khalil Al-Khwarizmi Engineering Journal, Vol. 11, No. 3, P.P. 11- 19(2015) 13 3. Mechanical System Modeling The equations of motion of this system involving a rotary flexible link manipulator, involves modeling the rigid rotational base and the flexible link together as rigid bodies. a simplification of the partial differential equation describe the motion of a the flexible link, a single degree of freedom approximation in this system is used. At the first start with the derivation of the dynamic model of the system by computing various rotational moments of inertia terms. The rotational inertia for a flexible link is given by:- J���� = �� m����L� …(1) Where: L is the total flexible link length , and mlink is the total mass of the flexible link, For a single degree of freedom of this system, the natural frequency is related with torsional stiffness of the link and rotational inertia in the following manner:- ω�� ���������� … (2) Where: �� n was found experimentally and Kstiff is the lateral stiffness constant of the link ,defined as:- ������ = �� … (3) Where: F is the force applied at the tip of the link and is the tip deflection. = � !"� #$ … (4) And substitutes equation (4) into equation (3) yields the flexural stiffness of cantilever beam :- ������ = � #$!" … (5) Where I is the moment of area of the link and E is the young modules of elasticity of the link. In addition, any frictional damping effects between the flexible link and the rotary base was neglected. Next, the generalized dynamic equation of the system was driven for the tip and base using The Lagrange’s energy equations of motion in terms of a set of generalized variables phi θ and alpha α ,where α is the angle of tip deflection and θ is the base rotation given in the following:- %%� & %'%(′) − %'%( + %,%( = -( … (6) Where: P is the total potential energy of the system and T is the total kinetic energy of the system, and Qi is the i th generalized force within the ith degree of freedom. the virtual forces that applied onto the generalized coordinates obtained from Qθand Qα, be: -(./ … (7) -0 = 0 … (8) The dynamic equations was driven for the mechanical subsystem from: 2.. = − 4567889:;5< = + �9:;5< / … (9) =.. = −������ & �9:;5< + �9:;5<) = + �9:;5< / … (10) Next, rewriting equations (9) and (10) into a state space form that gives the following equation[10]: >2?=?2@=@ A = BC CC D00 00 1 00 10 − 4567889:;5< 0 00 −������ & �9:;5< + �9:;5<) 0 0FG GG H >2=2?=? 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