| The design and optimization of mechanical structure of palletizing robot are related to the workspace design and optimization, trajectory planning, energy consumption and positioning accuracy. This is also a crucial basis in choosing the appropriate driving motor type, thus this has always been one of the important tasks in the development of industrial robot.Based on this background, this thesis is aimed at reducing the peak driving power and energy consumption and meet the requirement of compact and lightweight structure of the robot. The work of optimizing the structure parameters of palletizing robot is carried out.Firstly, the hybrid robot is simplified to a serial robot with closed chain. A coordinate system is established by D-H method and the forward and inverse solution of the kinematic equations is solved. Meanwhile, the relationship between the position of the palletizing robot task space and working space is analyzed and a method of transforming the minimum rectangular task space into a planar rectangular task space is proposed. Based on this works above, a quantitative evaluation method of workspace of palletizing robot is presented.On the other hand, the dynamic equations of hybrid robot with closed chain are derived by using the Kane method and the correctness of the equation is verified by the SimMechanics model. The peak value of driving force and energy consumption is proposed as the robot dynamic performance evaluation index and the influence of key structure parameters on the dynamic performance of the robot is analyzed.A new method for the structure parameter optimization is proposed by analyzing the kinematics and dynamics performance of the robot. The method can be divided into two steps. Firstly, the optimal length of arm and the range of joint angle are curtained with the consideration of rational workspace and compact structure. Secondly, the optimal cross section dimension and position of mass center are achieved to minimize the peak value and energy consumption of the robot. After the optimization, in a new parameter combination, the structure stiffness of the optimal robot is no less than the original robot, the length of the bar and the quality are reduced, and the utilization rate of the work space is improved and the driving peak force and energy consumption is reduced. In the end, the performance analysis and parameter optimization method of the robot are concluded, a software platform of the 4 Degrees of Freedom palletizing robot with closed-chain structure is developed to accelerate the structural design and parameter optimization of same structure form robot. |
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