Predictively adjustable hydraulic pressure rails
A robotic device may traverse a path in a direction of locomotion. Sensor data indicative of one or more physical features of the environment in the direction of locomotion may be received. The implementation may further involve determining that traversing the path involves traversing the one or more physical features of the environment. Based on the sensor data indicative of the one or more physical features of the environment in the direction of locomotion, a hydraulic pressure to supply to the one or more hydraulic actuators to traverse the one or more physical features of the environment may be predicted. Before traversing the one or more physical features of the environment, the hydraulic drive system may adjust pressure of supplied hydraulic fluid from the first pressure to the predicted hydraulic pressure.
1. A control system of a robotic device comprising:
a limb including a plurality of hydraulic actuators;
one or more processors; and
data storage configured to store instructions, that when executed by the one or more processors, cause the control system to:
cause the robotic device to perform a task that involves actuating the plurality of hydraulic actuators, wherein causing the robotic device to perform the task comprises (i) causing a pump of a hydraulic drive system to supply hydraulic fluid at a first pressure to at least one of the plurality of hydraulic actuators, and (ii) causing the plurality of hydraulic actuators to follow respective task trajectories;
during performance of the task, repeatedly track, over a pre-determined period of time, respective actuator trajectories of the plurality of hydraulic actuators that perform a portion of the task;
based on the tracked respective actuator trajectories, determine a plurality of deviations of the respective tracked actuator trajectories from the respective task trajectories;
after the pre-determined period of time and responsive to the determination of the plurality of deviations, predict, based on the tracked respective actuator trajectories, a second pressure with which to actuate the at least one of the plurality of hydraulic actuators during a subsequent portion of the task;
cause the pump of the hydraulic drive system to adjust pressure of the supplied hydraulic fluid from the first pressure to the second pressure during a non-instantaneous adjustment period before performing the subsequent portion of the task; and
after the non-instantaneous adjustment period, cause the hydraulic drive system to supply hydraulic fluid at the second pressure to the at least one of the plurality of hydraulic actuators during the subsequent portion of the task.
2. The control system of claim 1 , wherein the limb is a leg, wherein causing the robotic device to perform the task comprises causing the robotic device to traverse a path toward a destination, and wherein the instructions further cause the control system to:
track respective loads on the respective hydraulic actuators over a portion of the path;
based on the tracked respective loads, determine that the leg has slipped at least once over the portion of the path; and
responsive to the determination that the leg has slipped over the portion of the path, cause the hydraulic drive system to increase pressure of the supplied hydraulic fluid to a third pressure.
3. The control system of claim 1 , wherein the limb is a robotic manipulator, wherein causing the robotic device to perform the task comprises causing the robotic manipulator to pick up an object, wherein the robotic manipulator comprises the at least one hydraulic actuator, and wherein the instructions further cause the control system to:
track a load on the at least one hydraulic actuator borne in picking up the object;
determine that picking up the object is saturating the first pressure; and
responsive to the determination that picking up the object is saturating the first pressure, cause the pump of the hydraulic drive system to increase pressure of the supplied hydraulic fluid to a third pressure.
4. The control system of claim 1 , wherein the hydraulic drive system comprises a first pressure rail and a second pressure rail, and wherein the instructions further cause the control system to:
based on respective loads on the plurality of actuators, determine that the task involves a cyclical load on the plurality of actuators;
adjust the first pressure rail to the second pressure, wherein the second pressure is sufficient to actuate a first portion of the cyclical load; and
adjust the second pressure rail to a third pressure, wherein the third pressure is sufficient to actuate a second portion of the cyclical load.
5. The control system of claim 4 , wherein the cyclical load on the plurality of actuators is due to the robotic device moving according to a cyclic gait.
6. A method comprising:
causing, by one or more processors, a robotic device to perform a task that involves actuating a plurality of hydraulic actuators of the robotic device, wherein the plurality of hydraulic actuators are disposed upon a limb of the robotic device, and wherein causing the robotic device to perform the task comprises (i) causing a pump of a hydraulic drive system to supply hydraulic fluid at a first pressure to at least one of the plurality of hydraulic actuators, and (ii) causing the plurality of hydraulic actuators to follow respective task trajectories;
during performance of the task, repeatedly tracking, by the one or more processors over a pre-determined period of time, respective actuator trajectories of the plurality of hydraulic actuators that perform a portion of the task;
based on the tracked respective actuator trajectories, determining, by the one or more processors, a plurality of deviations of the respective tracked actuator trajectories from the respective task trajectories;
after the pre-determined period of time and responsive to the determination of the plurality of deviations, predict, based on the tracked respective actuator trajectories, a second pressure with which to actuate the at least one of the plurality of hydraulic actuators during a subsequent portion of the task;
causing, by the one or more processors, the pump of the hydraulic drive system to adjust pressure of the supplied hydraulic fluid from the first pressure to the second pressure during a non-instantaneous adjustment period before performing the subsequent portion of the task; and
after the non-instantaneous adjustment period, causing, by the one or more processors, the hydraulic drive system to supply hydraulic fluid at the second pressure to the at least one of the plurality of hydraulic actuators during the subsequent portion of the task.
7. The method of claim 6 , wherein the limb is a leg, and wherein causing the robotic device to perform the task comprises causing the robotic device to traverse a path toward a destination, the method further comprising:
tracking respective loads on the respective hydraulic actuators over a portion of the path;
based on the tracked respective loads, determining that the leg has slipped at least once over the portion of the path; and
responsive to the determination that the leg has slipped over the portion of the path, causing the hydraulic drive system to increase pressure of the supplied hydraulic fluid to a third pressure.
8. The method of claim 6 , wherein the limb is a robotic manipulator, wherein causing the robotic device to perform the task comprises causing the robotic manipulator to pick up an object, wherein the robotic manipulator comprises the at least one hydraulic actuator, and wherein the instructions further cause the control system to:
track a load on the at least one hydraulic actuator borne in picking up the object;
determining that picking up the object is saturating the first pressure; and
responsive to the determination that picking up the object is saturating the first pressure, causing the pump of the hydraulic drive system to increase pressure of the supplied hydraulic fluid to a third pressure.
9. The method of claim 6 , wherein the hydraulic drive system comprises a first pressure rail and a second pressure rail, the method further comprising:
based on respective loads on the plurality of actuators, determining that the task involves a cyclical load on the plurality of actuators;
adjusting the first pressure rail to the second pressure, wherein the second pressure is sufficient to actuate a first portion of the cyclical load; and
adjusting the second pressure rail to a third pressure, wherein the third pressure is sufficient to actuate a second portion of the cyclical load.
10. The method of claim 6 , wherein the cyclical load on the plurality of actuators is due to the robotic device moving according to a cyclic gait.
11. A non-transitory computer-readable medium, having stored thereon program instructions that, upon execution by one or more processors, cause a robotic device to perform operations comprising:
causing the robotic device to perform a task that involves actuating a plurality of hydraulic actuators of the robotic device, wherein the plurality of hydraulic actuators are disposed upon a limb of the robotic device, and wherein causing the robotic device to perform the task comprises (i) causing a pump of a hydraulic drive system to supply hydraulic fluid at a first pressure to at least one of the plurality of hydraulic actuators, and (ii) causing the plurality of hydraulic actuators to follow respective task trajectories;
during performance of the task, repeatedly tracking, over a pre-determined period of time, respective actuator trajectories of the plurality of hydraulic actuators that perform a portion of the task;
based on the tracked respective actuator trajectories, determining a plurality of deviations of the respective tracked actuator trajectories from the respective task trajectories;
after the pre-determined period of time and responsive to the determination of the plurality of deviations, predict, based on the tracked respective actuator trajectories, a second pressure with which to actuate the at least one of the plurality of hydraulic actuators during a subsequent portion of the task;
causing the pump of the hydraulic drive system to adjust pressure of the supplied hydraulic fluid from the first pressure to the second pressure during a non-instantaneous adjustment period before performing the subsequent portion of the task; and
after the non-instantaneous adjustment period, causing the pump of the hydraulic drive system to supply hydraulic fluid at the second pressure to the at least one of the plurality of hydraulic actuators during the subsequent portion of the task.
12. The non-transitory computer-readable medium of claim 11 , wherein the limb is a leg, and wherein causing the robotic device to perform the task comprises causing the robotic device to traverse a path toward a destination, the operations further comprising:
tracking respective loads on the respective hydraulic actuators over a portion of the path;
based on the tracked respective loads, determining that the leg has slipped at least once over the portion of the path; and
responsive to the determination that the leg has slipped over the portion of the path, causing the hydraulic drive system to increase pressure of the supplied hydraulic fluid to a third pressure.
13. The non-transitory computer-readable medium of claim 11 , wherein the limb is a robotic manipulator, wherein causing the robotic device to perform the task comprises causing the robotic manipulator to pick up an object, wherein the robotic manipulator comprises the at least one hydraulic actuator, and wherein the instructions further cause the control system to:
track a load on the at least one hydraulic actuator borne in picking up the object;
determining that picking up the object is saturating the first pressure; and
responsive to the determination that picking up the object is saturating the first pressure, causing the pump of the hydraulic drive system to increase pressure of the supplied hydraulic fluid to a third pressure.
14. The non-transitory computer-readable medium of claim 11 , wherein the hydraulic drive system comprises a first pressure rail and a second pressure rail, the operations further comprising:
based on respective loads on the plurality of actuators, determining that the task involves a cyclical load on the plurality of actuators;
adjusting the first pressure rail to the second pressure, wherein the second pressure is sufficient to actuate a first portion of the cyclical load; and
adjusting the second pressure rail to a third pressure, wherein the third pressure is sufficient to actuate a second portion of the cyclical load.
15. The non-transitory computer-readable medium of claim 11 , wherein the cyclical load on the plurality of actuators is due to the robotic device moving according to a cyclic gait.