Robotic system with independently controllable higher derivatives
A robotic system with independently controllable higher derivatives is disclosed. An indication is received of a trajectory through which an end effector comprising a robotic arm is to be moved. A plan is determined to use a combination of one or more motors and one or more energy removal devices to move one or more elements comprising the robotic arm in a manner that will result in the end effector being moved through the trajectory, including by using the one or more motors to apply torque to said one or more elements comprising the robotic arm during a first interval and using the one or more energy removal devices to remove energy from one or more of said elements during a second interval that starts after the start of the first interval. Commands to implement the plan are sent via a communication interface.
1 . A robotic system, comprising:
a communication interface; and
a processor coupled to the communication interface and configured to:
receive an indication of a trajectory through which an end effector comprising a robotic arm is to be moved;
determine a plan to use a combination of one or more motors and one or more direct energy removal devices other than the one or more motors to move one or more elements comprising the robotic arm in a manner that will result in the end effector being moved through the trajectory, including by using the one or more motors to apply torque to said one or more elements comprising the robotic arm during a first interval to cause the velocity of the end effector to increase to a maximum velocity as the end effector moves through a first segment of the trajectory and using the one or more direct energy removal devices to remove energy from one or more of said elements during a second interval that starts after the start of the first interval to cause the velocity of the end effector to decrease as the end effector moves through a second segment of the trajectory and to come to an end effector velocity of zero at an end location associated with an end of the trajectory; and
send via the communication interface commands to implement the plan;
wherein the direct energy removal devices are configured to remove but not add energy and using the one or more direct energy removal devices to remove energy from one or more of said elements during the second interval comprises determining and applying a control input that is directly proportional to the amount of velocity to be removed; and
wherein said one or more direct energy removal devices are engaged selectively, while the said one or more motors are adding energy, removing the need to estimate velocity and the need to use motor current to damp.
2 . The system of claim 1 , wherein the trajectory comprises a segment of a larger trajectory.
3 . The system of claim 1 , wherein the processor is configured to determine the trajectory.
4 . The system of claim 1 , wherein the commands to implement the plan include a first set of commands to cause the one or more motors to apply torque to said one or more elements comprising the robotic arm during the first interval.
5 . The system of claim 4 , wherein the first set of commands comprises one or more commands each sent via the communication interface to a corresponding motor controller.
6 . The system of claim 5 , wherein the commands to implement the plan include a second set of commands to cause the one or more energy removal devices to remove energy from one or more of said elements during the second interval.
7 . The system of claim 1 , wherein the second interval starts prior to the end of the first interval.
8 . The system of claim 1 , wherein the second interval does not overlap with the first interval.
9 . The system of claim 1 , wherein the energy removal devices comprise brake systems or devices.
10 . The system of claim 1 , wherein the energy removal devices directly control the velocity of the one or more elements comprising the robotic arm.
11 . The system of claim 1 , wherein the energy removal devices directly control the velocity of the end effector.
12 . The system of claim 1 , wherein the plan to use a combination of one or more motors and one or more energy removal devices to move one or more elements comprising the robotic arm is determined without estimating the state of the robotic system.
13 . The system of claim 1 , wherein the plan to use a combination of one or more motors and one or more energy removal devices to move one or more elements comprising the robotic arm is determined without estimating the derivative state of the robotic system.
14 . The system of claim 1 , wherein using the combination of one or more motors and one or more energy removal devices to move one or more elements comprising the robotic arm enables the end effector to be moved through the trajectory in less time than would be required if only the one or more motors were used.
15 . The system of claim 1 , wherein using the combination of one or more motors and one or more energy removal devices to move one or more elements comprising the robotic arm increases throughput of the robotic system as compared to the throughput that would be achieved if only the one or more motors were used.
16 . A method to control a robotic system, comprising:
receiving an indication of a trajectory through which an end effector comprising a robotic arm is to be moved;
determining a plan to use a combination of one or more motors and one or more direct energy removal devices other than the one or more motors to move one or more elements comprising the robotic arm in a manner that will result in the end effector being moved through the trajectory, including by using the one or more motors to apply torque to said one or more elements comprising the robotic arm during a first interval to cause the velocity of the end effector to increase to a maximum velocity as the end effector moves through a first segment of the trajectory and using the one or more direct energy removal devices to remove energy from one or more of said elements during a second interval that starts after the start of the first interval to cause the velocity of the end effector to decrease as the end effector moves through a second segment of the trajectory and to come to an end effector velocity of zero at an end location associated with an end of the trajectory; and
sending via a communication interface commands to implement the plan;
wherein the direct energy removal devices are configured to remove but not add energy and using the one or more direct energy removal devices to remove energy from one or more of said elements during the second interval comprises determining and applying a control input that is directly proportional to the amount of velocity to be removed; and
wherein said one or more direct energy removal devices are engaged selectively, while the said one or more motors are adding energy, removing the need to estimate velocity and the need to use motor current to damp.
17 . The method of claim 16 , wherein the commands to implement the plan include a first set of commands to cause the one or more motors to apply torque to said one or more elements comprising the robotic arm during the first interval.
18 . The method of claim 17 , wherein the first set of commands comprises one or more commands each sent via the communication interface to a corresponding motor controller.
19 . The method of claim 18 , wherein the commands to implement the plan include a second set of commands to cause the one or more energy removal devices to remove energy from one or more of said elements during the second interval.
20 . A computer program product embodied in a non-transitory computer readable medium and comprising computer instructions for:
receiving an indication of a trajectory through which an end effector comprising a robotic arm is to be moved;
determining a plan to use a combination of one or more motors and one or more direct energy removal devices other than the one or more motors to move one or more elements comprising the robotic arm in a manner that will result in the end effector being moved through the trajectory, including by using the one or more motors to apply torque to said one or more elements comprising the robotic arm during a first interval to cause the velocity of the end effector to increase to a maximum velocity as the end effector moves through a first segment of the trajectory and using the one or more direct energy removal devices to remove energy from one or more of said elements during a second interval that starts after the start of the first interval to cause the velocity of the end effector to decrease as the end effector moves through a second segment of the trajectory and to come to an end effector velocity of zero at an end location associated with an end of the trajectory; and
sending via a communication interface commands to implement the plan;
wherein the direct energy removal devices are configured to remove but not add energy and using the one or more direct energy removal devices to remove energy from one or more of said elements during the second interval comprises determining and applying a control input that is directly proportional to the amount of velocity to be removed; and
wherein said one or more direct energy removal devices are engaged selectively, while the said one or more motors are adding energy, removing the need to estimate velocity and the need to use motor current to damp.
21 . The system of claim 1 , wherein the second interval overlaps with the first interval.
22 . The system of claim 21 , wherein during a portion of the second interval that overlaps with the first interval one or more of said direct energy removal devices are removing energy from an associated joint at a same time that a corresponding one or more of said motors are adding energy to the associated joint.