Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons
In this work, a generalized low-level controller is presented for sensor collection, motor input, and networking with a high-level controller. In hierarchically controlled exoskeletal systems, which utilize series elastic actuators (SEAs), the hardware for sensor collection and motor command is sepa...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-01-01
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| Series: | Sensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1424-8220/23/2/1014 |
| _version_ | 1797437178609926144 |
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| author | Connor W. Herron Zachary J. Fuge Madeline Kogelis Nicholas J. Tremaroli Bhaben Kalita Alexander Leonessa |
| author_facet | Connor W. Herron Zachary J. Fuge Madeline Kogelis Nicholas J. Tremaroli Bhaben Kalita Alexander Leonessa |
| author_sort | Connor W. Herron |
| collection | DOAJ |
| description | In this work, a generalized low-level controller is presented for sensor collection, motor input, and networking with a high-level controller. In hierarchically controlled exoskeletal systems, which utilize series elastic actuators (SEAs), the hardware for sensor collection and motor command is separated from the computationally expensive high-level controller algorithm. The low-level controller is a hardware device that must collect sensor feedback, condition and filter the measurements, send actuator inputs, and network with the high-level controller at a real-time rate. This research outlines the hardware of two printed circuit board (PCB) designs for collecting and conditioning sensor feedback from two SEA subsystems and an inertial measurement unit (IMU). The SEAs have a joint and motor encoder, motor current, and force sensor feedback that can be measured using the proposed generalized low-level controller presented in this work. In addition, the high and low-level networking approach is discussed in detail, with a full breakdown of the data storage within a communication frame during the run-time operation. The challenges of device synchronization and updates rates of high and low-level controllers are also discussed. Further, the low-level controller was validated using a pendulum test bed, complete with full sensor feedback, including IMU results for two open-loop scenarios. Moreover, this work can be extended to other hierarchically controlled robotic systems that utilize SEA subsystems, such as humanoid robots, assistive rehabilitation robots, training simulators, and robotic-assisted surgical devices. The hardware and software designs presented in this work are available open source to enable researchers with a direct solution for data acquisition and the control of low-level devices in a robotic system. |
| first_indexed | 2024-03-09T11:16:03Z |
| format | Article |
| id | doaj.art-8ec6d240232246699f8228aa483adcc6 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-09T11:16:03Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-8ec6d240232246699f8228aa483adcc62023-12-01T00:31:18ZengMDPI AGSensors1424-82202023-01-01232101410.3390/s23021014Design and Validation of a Low-Level Controller for Hierarchically Controlled ExoskeletonsConnor W. Herron0Zachary J. Fuge1Madeline Kogelis2Nicholas J. Tremaroli3Bhaben Kalita4Alexander Leonessa5Terrestrial Robotics Engineering and Controls (TREC) Laboratory, Virginia Tech, Blacksburg, VA 24060, USATerrestrial Robotics Engineering and Controls (TREC) Laboratory, Virginia Tech, Blacksburg, VA 24060, USATerrestrial Robotics Engineering and Controls (TREC) Laboratory, Virginia Tech, Blacksburg, VA 24060, USATerrestrial Robotics Engineering and Controls (TREC) Laboratory, Virginia Tech, Blacksburg, VA 24060, USATerrestrial Robotics Engineering and Controls (TREC) Laboratory, Virginia Tech, Blacksburg, VA 24060, USATerrestrial Robotics Engineering and Controls (TREC) Laboratory, Virginia Tech, Blacksburg, VA 24060, USAIn this work, a generalized low-level controller is presented for sensor collection, motor input, and networking with a high-level controller. In hierarchically controlled exoskeletal systems, which utilize series elastic actuators (SEAs), the hardware for sensor collection and motor command is separated from the computationally expensive high-level controller algorithm. The low-level controller is a hardware device that must collect sensor feedback, condition and filter the measurements, send actuator inputs, and network with the high-level controller at a real-time rate. This research outlines the hardware of two printed circuit board (PCB) designs for collecting and conditioning sensor feedback from two SEA subsystems and an inertial measurement unit (IMU). The SEAs have a joint and motor encoder, motor current, and force sensor feedback that can be measured using the proposed generalized low-level controller presented in this work. In addition, the high and low-level networking approach is discussed in detail, with a full breakdown of the data storage within a communication frame during the run-time operation. The challenges of device synchronization and updates rates of high and low-level controllers are also discussed. Further, the low-level controller was validated using a pendulum test bed, complete with full sensor feedback, including IMU results for two open-loop scenarios. Moreover, this work can be extended to other hierarchically controlled robotic systems that utilize SEA subsystems, such as humanoid robots, assistive rehabilitation robots, training simulators, and robotic-assisted surgical devices. The hardware and software designs presented in this work are available open source to enable researchers with a direct solution for data acquisition and the control of low-level devices in a robotic system.https://www.mdpi.com/1424-8220/23/2/1014hierarchically controlled systemseries elastic actuatorssensorsmicrocontrollercommunication |
| spellingShingle | Connor W. Herron Zachary J. Fuge Madeline Kogelis Nicholas J. Tremaroli Bhaben Kalita Alexander Leonessa Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons Sensors hierarchically controlled system series elastic actuators sensors microcontroller communication |
| title | Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons |
| title_full | Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons |
| title_fullStr | Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons |
| title_full_unstemmed | Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons |
| title_short | Design and Validation of a Low-Level Controller for Hierarchically Controlled Exoskeletons |
| title_sort | design and validation of a low level controller for hierarchically controlled exoskeletons |
| topic | hierarchically controlled system series elastic actuators sensors microcontroller communication |
| url | https://www.mdpi.com/1424-8220/23/2/1014 |
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