Robotic arm system and object avoidance methods

A system comprising:

• a base;
• a first arm segment;
• a second arm segment interposed between the base and the first arm segment, coupled to the first arm segment via a first actuatable axis, and coupled to the base via a second actuatable axis;
• an end effector coupled to an end of the first arm segment opposite the first actuatable axis;
• a first electrode arranged across a region of the first arm segment and electrically coupled to a first sense circuit;
• a controller configured to measure a first capacitance of the first sense circuit at a first time and to measure a second capacitance of the first sense circuit at a second time during actuation of the first actuatable axis and the second actuatable axis, the second time succeeding the first time;
• a processor configured to:
• actuate the first actuatable axis and the second actuatable axis to move the end effector from a first position in physical space at the first time to a second position in physical space at the second time;
• calculate a first rate of change in capacitance of the first sense circuit between the first time and the second time;
• issue a proximity alarm at the second time in response to the first rate of change in capacitance of the first sense circuit exceeding a threshold rate of change;
• and
• reduce a maximum actuation speed of the first actuatable axis and the second actuatable axis in response to the proximity alarm.

A method for controlling a robotic arm, the method comprising:

• moving the robotic arm through a trajectory;
• at a first time in which the robotic arm occupies a first position along the trajectory, measuring a first capacitance of a first sense circuit comprising a first electrode extending over a first arm segment of the robotic arm;
• at a second time in which the robotic arm occupies a second position along the trajectory, the second time succeeding the first time, measuring a second capacitance of the first sense circuit;
• calculating a first rate of change in capacitance of the first sense circuit based on a difference between the first capacitance and the second capacitance;
• transforming the first rate of change in capacitance of the first sense circuit into a speed of the first electrode relative to an external object;
• in response to the speed of the first electrode relative to an external object exceeding a speed of the robotic arm from the first position to the second position, issuing a proximity alarm for motion of a dynamic object toward the robotic arm;
• and
• ceasing motion of the robotic arm while the proximity alarm for motion of a dynamic object toward the robotic arm is current.

A method for controlling a robotic arm, the method comprising:

• moving the robotic arm through a trajectory by actuating a first actuatable axis interposed between a first arm segment and a second arm segment of the robotic arm and actuating a second actuatable axis interposed between the second arm segment and a base of the robotic arm;
• at a first time in which the robotic arm occupies a first position along the trajectory, measuring a first capacitance of a first sense circuit comprising a first electrode extending over a first arm segment of the robotic arm;
• at a second time in which the robotic arm occupies a second position along the trajectory, the second time succeeding the first time, measuring a second capacitance of the first sense circuit;
• calculating a first rate of change in capacitance of the first sense circuit based on a difference between the first capacitance and the second capacitance;
• calculating a second rate of change in capacitance of a second sense circuit between the first time and a second time, the second sense circuit comprising a third electrode extending over the second arm segment;
• in response to one of the first rate of change in capacitance and the second rate of change in capacitance exceeding a threshold rate of change, issuing a proximity alarm;
• and
• in response to the proximity alarm, setting a reduced maximum speed of rotation of the first actuatable axis and the second actuatable axis in response to the proximity alarm.

A system comprising:

• a base;
• a first arm segment;
• a second arm segment interposed between the base and the first arm segment, coupled to the first arm segment via a first actuatable axis, and coupled to the base via a second actuatable axis;
• an end effector coupled to an end of the first arm segment opposite the first actuatable axis;
• a first electrode arranged across a region of the first arm segment and electrically coupled to a first sense circuit;
• a second electrode arranged on a first side of the first arm segment between the end effector and the first electrode and electrically coupled to a second sense circuit;
• and
• a third electrode arranged on a second side of the first arm segment opposite the second electrode and electrically coupled to a third sense circuit;
• a controller configured to measure capacitance of the first sense circuit, the second sense circuit, and the third sense circuit during actuation of the first actuatable axis and the second actuatable axis;
• and
• a processor configured to unlock the first actuatable axis for manual manipulation in response to a first change in capacitance of the second sense circuit indicating contact between an external object and the first side of the first arm segment at a third time and in response to a second change in capacitance of the third sense circuit indicating contact between an external object and the second side of the first arm segment at approximately the third time.