Research Of Four Degree Of Freedom Manipulator Drawing Vector Characters And Graphics

In recent years,robots have been widely concerned by enterprises and researchers.Mechanical arm,as an important branch of the robot,has become a hot topic of current research.Robot arm have been applied in the industry,education,medicine,aerospace,military fields and so on.Mechanical arm writing and painting also has a broad application space in industrial spray and popular science education.In the process of writing,motor frequently start-stop influence writing speed and stability.In order to resolve this problem,this paper combining with a engineering project put forward a new writing robot based on the look-ahead interpolation algorithm.The writing robot uses the extraction algorithm to transform the trajectories of characters and graphics into the continuous small line segments,and look-ahead the small line segments.Then disperse the small line segments by the acceleration and deceleration interpolation algorithm.The tiny line segment transformed into the rotation angle of the joints by the inverse kinematics.Finally,the mechanical arm can quickly,stably and accurately write characters and draw graphics.The main research contents of this paper are as follows:(1)Manipulator modeling and positive-inverse kinematics analysis.The principle of establishing the manipulator model with D-H parameter method is explained.On the base of the principle,the model of four-degree-of-freedom manipulator is established.The theory of kinematics of the manipulator is analyzed.The multiple solutions of the inverse kinematics are optimized.(2)Trajectory planning and simulation of manipulator.The trajectory planning theory of Cartesian space and joint space is expounded.The principle and implementation of the acceleration and deceleration linear interpolation algorithm used in writing robot are studied.The asymmetric velocity planning method are used to realize the smooth transition of velocity and acceleration in linear interpolation algorithm.In order to verify the correctness of the inverse kinematics and the trajectory planning theory,the robot toolbox is used to simulate the inverse kinematics and trajectory planning of the manipulator.(3)Writing control system software design and experiment.Firstly,the overall structure of the software is designed,and then the control system software is designed according to the three layers.Its include the presentation layer,the business logic layer and the data access layer.The core layer is the business logic layer which target is drawing vector characters and graphics.In order to draw the vector characters,we first analyze the structure of the vector characters in the windows platform,and then use the class library of.NET to develop the character extraction algorithm.In order to draw vector graphics,we use graphics software to draw vector graphics and generate PLT,and then design the graphics extraction algorithm based on PLT file.Finally,the small line look-ahead algorithm used in drawing vector characters and graphics are achieved,and the validity of the algorithm is verified by experiments.The innovation of this paper are as follows:(1)This paper achieved a four-degree-of-freedom manipulator to draw vector characters and graphics by analyzing the robot arm modeling,kinematics analysis,trajectory planning and design the computer control system.(2)The acceleration and deceleration linear interpolation algorithm is used to achieve a continuous writing speed and acceleration.The trajectory is miniaturized and the accuracy of writing path is improved.The look-ahead algorithm is used to look-ahead the trajectory.It makes begin and end speed of the small line segment nonzero,improving the motor rotation coherence and stability,avoiding the motor from the frequent start and stop,extending the service life of motor,also increasing the writing speed.The experimental results show that the writing robot can correctly write and draw,at the same time,the average speed of writing reached 31mm/s,the accuracy reached 0.02 mm after using the interpolation algorithm.The control system also can display the specific position of the arm in the process of writing through the computer interface,...