matlab挠率算法,中国科学院沈阳自动化研究所

其他摘要To overcome the limitations, this work is done under the national natural science foundation, focusing on the key technologies of continuum robots including distal touch perception, accurate shape tracking, path planning and robot control based on multi-sensor feedback. Details are as follows: This paper studied the distal touch perception technology for continuum robots. Based on the theory of mutual inductance coupling, a tri-axial electromagnetic deformation sensor with four-coil structure is designed. The deformation of elastomer caused by external forces is measured by using the mutual inductance variations between the four receiving coils and transmitting coil. The paper designed corresponding lock phase amplifier circuit to pick up the weak sensing voltage variations caused by micro-deformation. The relations between deformation, mutual inductance and sensing voltage were explored and the model was established, and the demodulation algorithms were derived based on simulation and experimental data analysis. The proposed electromagnetic sensor can measure the distal deformation information of surgical instrument and their interactions with human tissue. Furthermore, it can be combined with elastomer mechanical model to study the 3D force sensing technology of surgical instruments. For the continuum robotic sensing technologies, the reconstruction error of FBG shape senor is gradually increasing with the integral length, and the commonly used visual method has poor robustness and is easy to be distracted by illumination, occlusion, shadows, etc. To overcome these limitations, this paper presents an accurate and robust shape and distal pose tracking method for continuum robot by using extended Kalman filter (EKF) for fusion of FBG shape data and stereo vision data to compensate for their own shortcomings. Firstly, the parameters of robot Jacobian matrices are obtained by using the empirical kinematics model, and the positioning accuracies of FBG shape sensor and stereo vision were evaluated based on experiments. The relations between FBG positioning error, kinematical model error and continuum length were numerically presented in sections, so that the EKF can give them with different weights at different positions. This form can improve shape tracking accuracy.Two experimental cases are conducted to verify the system accuracy and robustness, and the results indicate that the fusion algorithm can improve the system tracking accuracy of a single senor and keep it working robustly when stereo vision is distracted during surgery. The paper proposed a path planning algorithm for continuum robots with infinite degrees of freedoms (DOFs), and explored the kinematic constraints and reachability constraints that need to be satisfied in the process of robot movement. Because of the characters of material, the trajectories followed by continuum robots must satisfy the maximum curvature and torsion constraints, and their continuity constraints. Besides, the end-effort should be pointed to the target tissue at the goal point to ensure the effectiveness of the surgery. This paper presents a path and trajectory planning algorithm based on back Rapidly-exploring Random Trees (BRRTs) for continuum robots working in a “follow-the-leader” manner. The maximum curvature and torsion restrictions were imposed by limiting the growth direction of random sampling points in 3D space based on piecewise constant curvature assumption and curvatures’ geometric definitions under Frenet coordinate. The trajectory was reconstructed by integrating the tangent vector at the discrete point which was calculated based on curvatures interpolation algorithm and Frenet formula. The paper reduced the 3D planning into 2D one to remove the error and reduce the control complexity. The extraneous waypoints were pruned based on permutation algorithms, and the trajectory was optimized by combining Frenet-based and third-order Bezier-based curve to achieve a smooth and kinematics and accessibility constrained path. Finally, an experimental platform for continuum robots was built. An accurate control method based on multi-sensor feedback and inverse kinematics was proposed. The 3D surgical scene was reconstructed based on stereo vision. The target tissue and obstacle area were chosen manually and assumed to be cuboid in 3D space. The safety threshold was set according to the geometric size of continuum robot. Both the contact detection experiment between distal point and target tissue and collision experiment between robot body and obstacle were carried out. In conclusion, this paper aims at the bottleneck issues of clinical application of continuum robots and focus on the problem of robot imprecise manipulation due to lack of perceptual methods, and mainly studied the key technologies of distal perception, accurate shape tracking method and path planning. The simulation and experiments were implemented to validate the effectiveness of the proposed designs or methods. Solutions to these limitations can provide a theoretical foundation for the subsequent associated techniques, such as human-robot interaction, semi-automatic or automatic surgery and human-computer collaboration.