Contact Estimation in Robot Interaction

Abstract

In the paper, safety issues are examined in a scenario in which a robot manipulator and a human perform the same task in the same workspace. During the task execution, the human should be able to physically interact with the robot, and in this case an estimation algorithm for both interaction forces and a contact point is proposed in order to guarantee safety conditions. The method, starting from residual joint torque estimation, allows both direct and adaptive computation of the contact point and force, based on a principle of equivalence of the contact forces. At the same time, all the unintended contacts must be avoided, and a suitable post-collision strategy is considered to move the robot away from the collision area or else to reduce impact effects. Proper experimental tests have demonstrated the applicability in practice of both the post-impact strategy and the estimation algorithms; furthermore, experiments demonstrate the different behaviour resulting from the adaptation of the contact point as opposed to direct calculation.

External force estimation of fracture reduction robot based on force residual method

“…The reduction force of the robot changing with the xaxis distance can be calculated by equation (23), as shown in Figure 6. The reduction force gradually increases with the increase of the x-axis displacement.…”

“…22 To ensure the safety of interaction between humans and robots, a torque control strategy and the residual error of the tracking error are adopted to estimate the external force, which can avoid all unintended contact, and a suitable collision strategy is considered to reduce the damage caused by the collision. 23 Various sensorless external force estimation methods above are currently mainly used for series robots. There are few relevant literatures on the external force estimation of parallel robots.…”

Collision detection algorithm for collaborative robots considering joint friction

“…The data points were fitted using the least square method with a MATLAB toolbox. The fitting function adopted the model expressed in equation (17). The results are shown in Figure 4, and the fitting coefficients for all joints are shown in Table 1.…”

Short-Transient Discrete Time-Variant Filter Dedicated for Correction of the Dynamic Response of Force/Torque Sensors

“…However, the most attractive approach is to avoid manipulating the structure of the robot. Methods of improvement of dynamic properties of force sensors may be helpful in this case, especially in the critical phase of establishing the contact with the environment [12]. This paper describes commercially available filters, used in one of the most commonly known force sensors JR3 [13].…”