Teleoperation robots remain superior to fully automated robots in complicated and unstructured environments (e.g., in-orbit assembly). However, the collision risk is also greatly increased in these environments. Therefore, the teleoperation robot should possess the capability of collision risk perception and be configured with security assistance strategy to improve safety and efficiency. With this objective in mind, this paper proposes a collision risk assessment system based on fuzzy theory, which comprehensively considers the effects of shortest distance, operation speed, and delay time. The introduction of fuzzy theory makes the risk assessment results more accurate. Furthermore, this paper also proposes a creative discrete expandable bounding box method to make the calculation of the nearest distance between complicated obstacles and the robot more efficient and faster. Secondly, to improve the safety and efficiency of teleoperation, this paper proposes a set of teleoperation assistance strategies for teleoperation robots based on collision risk. The strategies include partial view highlighting, variation in the motion mapping ratio, and haptic risk warning, all of which are achieved in the graphical interactive interface. Finally, this paper verifies the proposed collision risk model and the operation assistant strategy through experiments. The results show that the proposed fuzzy collision risk model has a correct trend with risk factors, and the proposed operation assistance strategies can effectively reduce the robot collision risk and improve the safety of teleoperation robots. In conclusion, this research contributes to the collision risk assessment and obstacle avoidance assistance strategy of teleoperation robots.

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Collision Risk Assessment and Operation Assistant Strategy for Teleoperation System

Compared with rigid robotic arms, soft robotic arms have the advantages of high degree of freedom, lightness, and flexibility. However, insufficient torque and overshoot often cause difficulties in arm control. A prototype of a wire-driven robotic arm is proposed. The design concept of the robotic arm comes from the skeletal joints of snakes, which are formed by a combination of multiple solid polygons and spherical joints. The bending process is similar to the muscle contraction when the snake's body is curled. A look-up table based servo control method is presented to rotate the motor to drive the arm to bend and move to a specific point within the bending range. The motion model of the robot arm is established by the MATLAB Simulink, and the simulation results are compared with the actual operation results to verify the controllability and positioning accuracy of the robotic arm.

Design and Implementation of Wire-Driven Multi-Joint Robotic Arm

Compared with rigid robotic arms, soft robotic arms have the advantages of high degree of freedom, lightness, and flexibility. However, insufficient torque and overshoot often cause difficulties in arm control. A prototype of a wire-driven robotic arm is proposed. The design concept of the robotic arm comes from the skeletal joints of snakes, which are formed by a combination of multiple solid polygons and spherical joints. The bending process is similar to the muscle contraction when the snake's body is curled. A look-up table based servo control method is presented to rotate the motor to drive the arm to bend and move to a specific point within the bending range. The motion model of the robot arm is established by the MATLAB Simulink, and the simulation results are compared with the actual operation results to verify the controllability and positioning accuracy of the robotic arm. 

Collision risk assessment and automatic obstacle avoidance strategy for teleoperation robots

Beidou satellite navigation system (BDS) is a global satellite navigation system built by China. It will provide global coverage of all-weather, all-time, high accuracy, high reliability positioning, navigation and timing services around 2020. With the development of BDS application, users’ requirements for accuracy, integrity, availability, continuity have been gradually improved. In BDS service performance specification, only signal-in-space continuity is defined, but no positioning service continuity is defined. In this paper, we first put forward the definition of the positioning service continuity standards, and evaluate the availability and continuity of BDS positioning service by using the records from several receiver sites in China. The results show that the availability of BDS can reach 99.47% and the continuity can reach 0.9991/h. The conclusion of this paper can provide theoretical reference for the civil aviation application of BDS.

Shuo Wang

Papers

Collision risk assessment and automatic obstacle avoidance strategy for teleoperation robots

Service Continuity Assessment of Beidou Satellite Navigation System