Maintaining free-drive mode of robot arm for period of time

A method of operating a robotic arm in a free-drive mode of operation, the method comprising:

• keeping the robotic arm in a posture that is static when only gravity acts on the robotic arm;
• changing the posture of the robotic arm when an external force different from gravity is applied to the robotic arm;
• monitoring a value of at least one parameter of at least one sensor associated with a joint of the robotic arm;
• comparing the value of the at least one parameter to at least one threshold value;
• keeping the robotic arm in the free-drive mode of operation for a predetermined period of time;
• and
• causing the robotic arm to leave the free-drive mode of operation and return to normal mode of operation when the value of the at least one parameter does not exceed the at least one threshold value within the predetermined period of time.

A system comprising a robotic arm, the system comprising:

• a base;
• a tool flange;
• joints connecting the base and the tool flange, each of the joints comprising:
• an output flange rotatable in relation to a body of a joint;
• a motor configured to rotate the output flange;
• and
• at least one sensor for providing a sensor signal indicative of at least one of an angular position of the output flange, an angular position of a shaft of the motor, or a current of the motor;
• and
• at least one robot controller configured to control the joints by controlling motor torque of one or more motors based on one or more sensor signals, the at least one robot controller being configured to perform operations comprising:
• monitoring a value of at least one parameter of at least one sensor, the at least one parameter being based on a sensor signal;
• comparing the value of the at least one parameter to at least one threshold value;
• and
• causing the robotic arm to leave a free-drive mode of operation and to return to normal mode of operation when the value of the at least one parameter does not exceed the at least one threshold value;
• wherein in the free-drive mode of operation, a posture of the robotic arm is changeable through application of force to the robotic arm and where, in the absence of the force, the at least one robot controller is configured to maintain a posture of the robotic arm.