Robot system
A robot system for human-robot collaboration is disclosed that includes one or more proximity sensing elements disposed on the movable parts of the robot, joint position sensing sensors, and a safety control module connects the proximity sensing element and joint position sensing sensors and monitors the speed of the robot and the proximity distance to the objects and stop the robot safely when speed exceed the set limit. The safety control module switches the safety status of the robot when a set proximity distance threshold is triggered. Then, multiple embodiments of the safety status triggered by proximity sensing are introduced for different processes of the human-robot collaboration, includes separation monitoring, force limiting for bumping, and manipulation of the robot. Furthermore, embodiments of utilizing different types of sensors to implement the proximity sensing elements are also disclosed.
1 . A robot system comprising:
movable parts having a base and a tool end;
at least one actuator configured to drive at least one of the movable parts;
a proximity sensor disposed on at least one of the movable parts;
a joint position sensor communicatively coupled to the at least one actuator;
one or more processors configured to
measure a speed of the movable parts using the joint position sensor,
measure a distance to an object using the proximity sensor,
stop motion of the movable parts in response to the measured speed exceeding a speed limit, and
slow or stop the motion of the movable parts when the measured distance falls below a distance threshold; and
a sensing element of force or torque, the sensing element of force or torque being different from the proximity sensor and being communicatively coupled to the one or more processors, the one or more processors being further configured to
compute, based on a reading from the sensing element of force or torque, a dynamic model of the movable parts to generate an estimated external force exerted on at least the tool end,
slow down a speed monitoring point to a set speed in response to the measured distance falling below the distance threshold, wherein the speed monitoring point is located at the tool end or on a tool attached to the tool end,
stop the movable parts in response to the estimated external force exceeding a set limit, and
stop the movable parts in response to the speed monitoring point moving faster than the speed limit.
2 . The robot system of claim 1 , wherein the proximity sensor comprises one or more proximity sensing cells and a deformable layer overlapping the one or more proximity sensing cells.
3 . The robot system of claim 2 , wherein the proximity sensor further comprises a support coupled to at least one of the movable parts, the one or more proximity sensing cells being interposed between the support and the deformable layer.
4 . The robot system of claim 3 , wherein the distance threshold is within the deformable layer.
5 . The robot system of claim 2 , wherein the proximity sensor further comprises a support coupled to at least one of the movable parts, the deformable layer being interposed between the support and the one or more proximity sensing cells.
6 . The robot system of claim 1 , wherein the one or more processors is configured to stop the motion of the movable parts when the measured distance falls below the distance threshold.
7 . The robot system of claim 1 , wherein the one or more processors is configured to slow the motion of the movable parts to below an additional speed limit lower than the speed limit when the measured distance falls below the distance threshold.
8 . The robot system of claim 7 , wherein the one or more processors is configured to stop the motion of the movable parts when the measured distance falls below an additional distance threshold, the additional distance threshold being less than the distance threshold.
9 . The robot system of claim 8 , wherein the one or more processors is configured to slow but not stop the motion of the movable parts when the measured distance is below the distance threshold and above the additional distance threshold.
10 . The robot system of claim 1 , wherein the set speed is the lower of:
a speed according to a set estimated external force limit, and
a speed according to the distance threshold.
11 . The robot system of claim 1 , the robot system being operable using a guide mode, the guide mode comprising a guiding function in which the one or more processors controls the motion of the movable parts according to distance readings from the proximity sensor.
12 . The robot system of claim 11 , wherein under the guide mode, the one or more processors disables a triggering function for the distance threshold.
13 . The robot system of claim 11 , wherein under the guide mode, the one or more processors is configured to stop the motion of the movable parts when the measured distance falls below the distance threshold and wherein the distance threshold is lower than a maximum allowable triggering distance of guiding.
14 . The robot system of claim 1 , wherein the sensing element of force or torque comprises a sensor selected from the group consisting of: a joint current sensor, a joint torque sensor, a force-torque sensor mounted to the tool attached to the tool end of the movable parts, and a force-torque sensor mounted to the base of the movable parts.
15 . The robot system of claim 1 , wherein the sensing element of force or torque comprises:
an additional proximity sensor; and
a deformable structure on the additional proximity sensor and interposed between the proximity sensor and the additional proximity sensor.
16 . The robot system of claim 1 , wherein the sensing element of force or torque comprises a sensor selected from the group consisting of: a pressure sensor, a contact force sensor, and an air sensor having a deformable air chamber.
17 . The robot system according to claim 1 , wherein the proximity sensor comprises a proximity sensor selected from the group consisting of: an ultrasonic proximity sensor, an optical proximity sensor, a radio proximity sensor, and a capacitive proximity sensor.
18 . The robot system according to claim 1 , wherein the one or more processors is configured to control a programmed speed of the movable parts to always fall below a speed limit.
19 . A method of operating a robot, the method comprising:
with at least one actuator, moving one or more movable parts of the robot;
with a proximity sensor disposed on the one or more movable parts, generating first sensor data indicative of a distance between the proximity sensor and an external object;
with a joint position sensor coupled to at least one actuator, generating second sensor data indicative of a speed of the one or more movable parts;
stopping motion of the one or more movable parts in response to the second sensor data indicating that the speed exceeds a threshold speed;
slowing but not stopping the motion of the one or more movable parts when the distance falls from a first distance that exceeds a first threshold distance to a second distance that is less than the first threshold distance and greater than a second threshold distance, the second threshold distance being less than the first threshold distance;
stopping the motion of the one or more movable parts when the distance falls below the second threshold distance;
with one or more processors, computing, based on a reading from a sensing element of force or torque, a dynamic model of the one or more movable parts to generate an estimated external force exerted on at least a tool end of the one or more movable parts, the sensing element of force or torque being different from the proximity sensor;
slowing down a speed monitoring point to a set speed in response to the measured distance falling below the distance threshold, wherein the speed monitoring point is located at the tool end or on a tool attached to the tool end,
stopping the one or more movable parts in response to the estimated external force exceeding a set limit, and
stopping the one or more movable parts in response to the speed monitoring point moving faster than the speed limit.