Lining Sun

A distance error based industrial robot kinematic calibration method

Purpose – The purpose of this paper is to present a distance accuracy-based industrial robot kinematic calibration model. Nowadays, the repeatability of the industrial robot is high, while the absolute positioning accuracy and distance accuracy are low. Many factors affect the absolute positioning accuracy and distance accuracy, and the calibration method of the industrial robot is an important factor. When the traditional calibration methods are applied on the industrial robot, the accumulative error will be involved according to the transformation between the measurement coordinate and the robot base coordinate. Design/methodology/approach – In this manuscript, a distance accuracy-based industrial robot kinematic calibration model is proposed. First, a simplified kinematic model of the robot by using the modified Denavit–Hartenberg (MDH) method is introduced, then the proposed distance error-based calibration model is presented; the experiment is set up in the next section. Findings – The experimental r...

Vision-based mobile robot localization and mapping using the PLOT features

Accurate localization and mapping play a pivotal role in mobile robot navigation. In this paper, we present a novel algorithm for mobile robot localization and mapping based on stereo vision. First a novel method is proposed to extract distinctive invariant image features, which is coined PLOT (Polynomial Local Orientation Tensor). The stability of these features to image translation, scaling, rotation and illumination changes makes them suitable landmarks for mobile robot localization and map building. The visual landmarks relative to the robot can be established by matching the PLOT features. Mobile robot localization is achieved by matching these distinctive landmarks in the current frame to the database map. RANSAC algorithm is employed for mobile robot pose estimate due to its efficiency. Meanwhile, the visual landmarks in the database map are updated correspondingly. Experimental results show that the proposed method based on the PLOT features achieves localization and mapping for mobile robot with higher precision.

Force control based robotic grinding system and application

A robotic grinding method based on force feedback is proposed in this paper. This method is used in polishing metal products like faucet handle which is made in zinc alloy. Force control technology is important in the grinding system. In the grinding process, grinding force is a pressure in a specified direction which is applied to the surface of the mold by polishing tools. The force should be controlled in some stable value to ensure the grinding quality. In order to maintain a constant and stable force throughout the process of grinding or polishing, force sensor is always required in order to measure the contact force between grinding tool and mold surface. At the same time, the measured data should be sent to the controller and according to it the controller can adjust the value of the predefined grinding force in different process conditions. Before robotic grinding, off-line programming method is used to simulate the grinding process. After simulation process, the grinding robot with force control method is applied in grinding faucet handle instead of human. Good grinding results are produced from the experiments with such methods.

Mopping module design and experiments of a multifunction floor cleaning robot

The autonomous cleaning robot has entered the practical stage, and is getting more and more popular. Currently most researches of the cleaning robot focus on sensor technology, location and environment modeling theory. And these researches have made great progress, which proves the practicability of the cleaning robot further. In this paper, we firstly propose a novel method to mop the floor by using a sponge, and use this method to design a mopping module in the frame work of a multifunction floor cleaning robot. Then the parameters of the module are optimized by analyzing the amount of the pumping out and recycling water. Lastly, a real experiment is carried out to validate the methods effectiveness.

A learning algorithm for model based object detection

Detecting objects in images and videos is a difficult task that has challenged the field of computer vision. Most of the algorithms for object detection are sensitive to background clutter and occlusion, and cannot localize the edge of the object. An objects shape is typically the most discriminative cue for its recognition by humans. This paper introduces a model based object detection method which uses only shape-fragment features. The object shape model is learned from a very small set of training images. And the object model is composed of shape fragments. The model of the object is in multi-scales. The results presented in this paper are competitive with other state-of-the-art object detection methods. The major contributions of this paper are the application of learned shape fragments based model for object detection in complex environment and a novel two-stage object detection framework.

Automated deep access ball bonder for MEMS packaging based on fast autofocus system

Ball bonding is one of the most commonly used form of packaging of the MEMS sensors. Batch fabrication of the conventional IC ball bonding equipment characteristics limit the flexibility of the MEMS packaging. Continuous zoom microscope as a flexible micro-vision system and the combination of manual ball bonder, automatic ball bonding system for MEMS packaging is established. By analyzing the zoom microscope imaging model, zoom microscope auto-focusing method is put forward to obtaining a clear picture of different multiples. The rough location of large-scale is achieved under low magnification, high magnification for precise positioning, using the zoom microscope continuous variable characteristics to realize a wide range of high-precision positioning. Finally, MEMS pressure sensor packaging experiments verify the systems utility.

The research of structure parameter optimization process for a novel parallel radiotherapy bed

In order to guarantee the preoperative and intraoperative precise positioning demand of the radiotherapy bed in the radiation process, utilizing the advantages of parallel mechanism, in this paper, a parallel structure radiotherapy bed was designed to meet the demands of high positioning precision, high stiffness, high carrying capacity and flexible configuration space which could cover the shortage of the conventional radiotherapy bed. Firstly, this paper analyzed the precise workspace of the radiotherapy bed with kinematics inverse solved by vector algebra method and studied the influence of workspace by changing the rule of all parameters as well as finding the relationships between them in the condition that the size of the moving platform and the fixed platform were limited. Then, in order to meet the requirements of stability and security of the radiotherapy bed, considering the workspace and the forces on it, a new parameter optimization process was proposed with constructing the objective function of the Jacobian matrix condition number, the universe average of condition number and the fluctuation of condition number. The simulation analysis results demonstrated that the overall performance of the radiotherapy bed was considerably improved with the smaller dimensions of the radiotherapy bed, the significantly reduced forces on the structure in the workspace and the smaller condition number of Jacobian matrix with uniform distribution in the whole workspace.

Research on force sensing system for a colonoscopy robot

A force-sensing system for a colonoscopy robot is proposed. It undertakes a modular design, composed of strain gauges. This paper first makes a modeling and simulation analysis of surface deformation for the colonoscopy robot. And then, based on the results of the analysis, the structural design of the sensor is improved. Finally, after designing a pressure sensing and signaling circuit, an experiment done on identifying the sensor parameter is described. The acceptable performances of the force sensing system are verified through experiments.