Abstract
The collision detection algorithm of the robot body previously needed to rely on the surface geometry information of the colliding object and no deformation was allowed during the collision process. To solve this problem, a new robot body collision detection algorithm that uses the force information of the six-axis force/torque sensor at the base to self-constrain is proposed which does not rely on the geometric information of the colliding object surface, and the deformation also allows deformation during the collision. In terms of sensor data preprocessing, a gravity and dynamic force compensation algorithm for the six-axis force/torque sensor at the base is proposed to ensure that the reading of the six-axis force/torque sensor at the base always maintains the value of 0 when the robot is working. Then, the robot is considered to have collided with the outside world when the sensor reading exceeds the set threshold. And a precision factor is proposed to analyze the influence of force and collision distance on the accuracy of the algorithm. Finally, the new algorithm proposed in this paper is compared with the traditional algorithm that relies on the geometric information of the colliding body surface. The experimental results indicate that the accuracy of the collision point detection algorithm proposed in this paper is close to that of the traditional method, but it does not need to rely on the geometric information of the collision body surface, and there is no requirement for whether there is deformation during the contact process. It can be concluded that the collision distance is the most important factor affecting the accuracy of the algorithm, followed by the conclusion of the magnitude of the collision force through the calculation of the precision factor. The results show that this method can effectively detect the collision point of the machine body, and the maximum error at the farthest point of the robot is 8.712%, which lays a certain foundation for the subsequent research on human-machine collaboration in small collaborative robots.
Highlights
With the development of robot technology, a variety of sensors such as vision, touch, and force were applied to robot systems
In order to make up for the above problems, a robot collision point detection algorithm for single point and single external force is proposed in this paper, and the gravity compensation and dynamic force compensation algorithms of the six-axis force/torque sensors at the base are described, perform simulation experiments to verify the algorithm
Compared with the traditional algorithms [18, 19] that use the geometric information of the collision surface to calculate the collision position, the algorithm proposed in this paper has a minimum error of only 1.5470%, and the maximum error is approximated by traditional methods
Summary
With the development of robot technology, a variety of sensors such as vision, touch, and force were applied to robot systems. The perception of force information plays a vital role in the hexacopter equipped researched by Ibrahim et al [4] and the new full-mobile robot and control system researched by Kilin et al [5]. The perception of force information is conducive to improving the robustness of the hexarotor and fully movable robot control. Six-axis force/torque sensors are widely used in industrial robot collision detection and feedback control [6,7,8]. In some smarter robot systems, six-axis force/torque sensors are used to implement functions such as tactile sensing, safety control, and collision detection [9,10,11,12,13,14]. It can be seen that collision detection and feedback control are two key functions of force perception, and collision position detection is one of the important contents of collision detection
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