Identification of Contact Position and Force Estimation on Manipulator Using Force Sensor Implemented on Base Frame

Abstract

Sensing is essential in human cooperative robots to realize safe and powerful operations against contact with the surrounding environment. Contact sensing has been studied for manipulators to avoid accidents caused by collisions between humans and robots. Conventional research has demonstrated that contact sensing requires many sensors or has a limited measurable range. In the conventional research without sensors, modeling systems, such as frictional force and plant parameters, have been used to estimate the contact force. However, a high reduction ratio mechanism for achieving powerful operations hinders accurate force estimation. This study proposes a method to estimate the contact force and contact position on a manipulator with a high reduction ratio mechanism by installing only one force/torque sensor on the base frame of the manipulator. By using the proposed method, the contact force and contact position can be detected regardless of the location where the contact force is applied. Furthermore, when the contact force is applied in a location where the contact position cannot be accurately estimated, an estimated disturbance or a link motion is used to determine the contact position. The effectiveness of the proposed method is validated through experiments.

Work in the Time of Covid-19: Actuators and Sensors for Rehabilitation Robotics

“…The latter extend prior studies that mainly discussed the translational motion of the planar motor moving parts and did not consider the rotational motion. Some of the previous studies considered forces other than in the translational direction, but they were mainly aimed at controlling small displacements in the rotational direction or magnetic levitation, which greatly limited the feasible rotation angle [60]- [62]. An overview of our alpha-prototype of the active 3-DOF flat actuator is shown in Fig 15. Permanent magnets are attached to the mover, and by controlling the excitation pattern of the coils on the stator side, we can control a 2-DOF horizontal and 1-DOF rotational motion.…”

Reaction Force-Based Position Sensing for Magnetic Levitation Platform with Exceptionally Large Hovering Distance

“…For example, in robotics, a force/torque sensor placed between the robotic arm and hand was used to estimate the position of a contact point with an object and monitor the contact state of the hand with the grasped object [24]. Additionally, a single force/torque sensor placed on the base frame of a manipulator was used to estimate the contact force and position at the end effector that interacts with humans and/or other robots [25]. Furthermore, in a micro-gripper, the sensed forces on both end effectors were used to determine their positions [26].…”