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1、Virtual Prototyping of a Parallel Robot actuated by Servo-Pneumatic Drives using ADAMS/ControlsWalter Kuhlbusch, Dr. Rdiger Neumann, Festo AG & Co., GermanySummaryAdvanced pneumatic drives for servo-pneumatic positioning allow for new generations of handlings and robots. Especially parallel robots a
2、ctuated by servo-pneumatic drives allow the realization of very fast pick and place tasks in 3-D space. The design of those machines requires a virtual prototyping method called the mechatronic design 1. The most suitable software tools are ADAMS for mechanics and Matlab/Simulink for drives and cont
3、rollers. To analyze the overall behavior the co-simulation using ADAMS/Controls is applied. The combination of these powerful simulation tools guarantees a fast and effective design of new machines.1. IntroductionFesto is a supplier for pneumatic components and controls in industrial automation.The
4、utilization of pneumatic drives is wide spread in industry when working in open loop control. Its limited however, when it comes to multipoint movement or path control. The development has been driven to servo-pneumatic drives that include closed loop control. Festo servo-pneumatic axes are quite ac
5、curate, thus they can be employed as drives for sophisticated tasks in robotics. The special advantage of these drives is the low initial cost in comparison to electrical and hydraulic drive systems. Servo-pneumatic driven parallel robots are new systems with high potentials in applications. The dyn
6、amical performance meets the increasing requirements to reduce the cycle times.One goal is the creation and optimization of pneumatic driven multi-axes robots. This allows us to support our customers, and of course to create new standard handlings and robots (Fig. 1).The complexity of parallel robot
7、s requires the use of virtual prototyping methods. Fig. 1. Prototypes of servo-pneumatic driven multi-axes machinesPreferred applications are fast multipoint positioning tasks in 3-D space. Free programmable stops allow a flexible employment of the machine. The point to point (ptp) accuracy is about
8、 0.5 mm. The continuous path control guarantees collision free movement along a trajectory.1.1. Why parallel robots?The main benefits using parallel instead of serial kinematics is shown in Fig. 2.Fig. 2. Benefits of robots with parallel kinematicsHigh dynamical performance is achieved due to the lo
9、w moved masses. While in serial robots the first axis has to move all the following axes, the axes of a parallel robot can share the mass of the workpiece. Furthermore serial axes are stressed by torques and bending moments which reduces the stiffness. Due to the closed kinematics the movements of p
10、arallel robots are vibration free for which the accuracy is improved. Finally the modular concept allows a cost-effective production of the mechanical parts. On the other hand there is the higher expense related to the control.1.2. Why Pneumatic Drives?The advantages of servo-pneumatic drives are: d
11、irect driveshigh accelerating power compact (especially rodless cylinders with integrated guidance) robust and reliable cost-effectiveDirect drives imply a high acceleration power due to the low equivalent mass in relation to the drive force. With pneumatic drives the relationship is particularly fa
12、vorable. Festo has already built up some system solutions, predominantly parallel robots (see Fig. 1), to demonstrate the technical potential of servo-pneumatics. Which performance can be reached is shown in Fig. 3. This prototype is equipped with an advanced model based controller that makes use of
13、 the computed torque method 3.Fig. 3. Performance of the Tripod2. Design MethodThe system design, where several engineering disciplines are involved in, requires a holistic approach. This method is the so-called mechatronic design. The components of a mechatronic system are the mechanical supporting
14、 structure, the servo drives as well as the control. All these components are mapped into the computer and optimized with respect to the mutual interaction. This procedure can be used to analyze and improve existing systems as well as to create new systems. The two main steps of the mechatronic desi
15、gn are first building models in each discipline, and secondly the analysis and synthesis of the whole system. These steps are done in a cycle for the optimization.The modeling can be carried out in two ways: Either you apply one tool to build up models in all disciplines, but with restrictions. The
16、other way is to use powerful tools in each discipline and to analyze the whole system via co-simulation. In this case you have to consider some specials of the solving method like communication step size or direct feedthrough behavior.2.1. Why Co-Simulation?Co-simulation is used because of the powerful tools, each specialized in its own discipline. ADAMS is an excellent tool for the mechanical part and Matlab/Simulink is
