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--- courses:456:2023:projects:456-2023-01:project-01 [2023/05/10 03:45] – [Project Report And Status] bbanks15
+++ courses:456:2023:projects:456-2023-01:project-01 [2023/05/11 04:01] (current) – [Reports and presentations] bbanks15
@@ Line 1: / Line 1: @@
 ======Transparency Optimization of the Galen Surgical System with a Frequency Domain Admittance Controller Design======
-**Last updated: 5/9/2023 at 8:13 PM**
+**Last updated: 5/10/2023 at 3:55 PM**
@@ Line 287: / Line 287: @@
 {{:courses:456:2023:projects:456-2023-01:TOGAC50_AMBF_in_admittancecontrolteleop.pdf| TOGAC50_AMBF_in_AdmittanceControlTeleop}}
+__**Single Axis Galen Implementation of Admittance Control**__
+Time allotted for the implementation and testing of one single axis of the Galen robot. The Z dimension was chosen and used to evaluate the admittance control’s ability to interpret the user’s input into a velocity reference.
+The following transfer functions for the X, Y, and Z axis were obtained for the real Galen robot system identification. Note that the actual system features a few new errors introducing variables. Two prominent variables that will be addressed here are the delay and the motor backlash.
+{{:courses:456:2023:projects:456-2023-01:tfreal.png?400|}}
+The tfest MATLAB estimator was able to estimate the transfer functions in addition to measuring the time delays. This time delay could be caused by several factors. A few of these factors are due to the control processing delay between communication from the mid-level control to low-level to ROS and the actual robot. The delay is also a result of the lagging time in the acceleration or inertia of the robot hardware. This is especially present in the case of motor backlash. When the commanded velocity or present velocity of the robot reaches zero, especially on robot initialization, commands that move the robot out of a stationary state must first overcome the effects of static friction. This is called motor backlash and can cause significant delays and shifting of the output signal.
+{{:courses:456:2023:projects:456-2023-01:zchirpout.png?400|}}
+//The output position of the real Galen robot, the velocity, and an fft of the velocity noise//
+Observe the above figure for the velocity input and output plot. The motor backlash delay can be seen at any point where the velocity out reaches zero. Until the robot can break the static friction and overcome the initial motor inertia, the velocity controller must quickly compensate to catch up to the reference.
+We also can see that the output velocity of the robot, in orange, is a rather noisy signal. This is due to the fact that we only have access to the position measuring crtk_command tools that observe the motor encoders. To get the velocity of the position signal, we use a finite differentiation method between the current timestep and the previous time step to derive the position.This introduces lots of noise, and in order to utilize a more precise velocity signal for feedback control it is important to filter the data.
+We ran an fft on the finite differentiated velocity to observe what appropriate cutoff frequency should be used and deemed 75 Hz was an appropriate frequency to use in a first order low pass filter.
+The above figure also shows an example of the response of the Z axis identification. This axis showed the smallest time delay of the 3 identified systems. We notice that this time delay is large rather large on the X axis and there are many factors still to be investigated that could be causing this. There is much more work to be done on the real system implementation and testing.
+For our current approach, we chose to start simply with a single axis where we were most confident to obtain a good admittance response. We found the Z to have the smallest time delay and the stability analysis was deemed the most stable according to the following maps.
+{{:courses:456:2023:projects:456-2023-01:zstabout.png?400|}}
+//Upper bound (with human and environment) impedance and Lower bound (only human) impedance stability and transparency maps for the Galen z axis.//
+With the above results we were able to select a set of gains for the human only contact impedance case and test them on the real Galen robot.
+{{:courses:456:2023:projects:456-2023-01:handovercontrol.jpg?400|}}
+// User interacting with the Galen robot end effector to apply a wrench//
+The admittance gains of 8kg and 20Ns/m were chosen for the mass and damping values respectively. A test was run for 10 seconds with the robot in gravity compensation mode. The user was instructed to wait 5 seconds and then apply an upwards input on the robot end effector. The following plot was obtained for the input reference velocity vs the input user force.
+ {{:courses:456:2023:projects:456-2023-01:galencontrol.png?400|}}
+//The recorded input reference velocity as calculated from the admittance controller and the measured true force from the Galen robot end effector sensor.//
+As anticipated, the robot tracked the force references and converted the input wrench to a clean and smooth velocity trajectory. Notice that even with the Galen gravity compensation on, during the 0 to 4 second period without human contact, the robot experiences a small downward force. This indicates that the Galen robot needs to be recalibrated or adjusted to better handle gravity compensation.
+The present gains for the admittance controller in this Z axis show a good level of admittance that feels smooth, light, and controllable. Qualitatively, compared to Z motions on the current on-board Galen controller, our controller is noticeably better at feeling more transparent. However true testing and evaluation of the controllers will prove if the results truly are more transparent.
 ======Project Close Out and Discussion======
-All of the minimum deliverables in section 1.3 were completed and delivered in the expected time frame. The controller package, interface instructions, and reports can be found on the project wiki.
+All of the minimum deliverables in the project were completed and delivered in the expected time frame.
 The expected deliverables are in progress. System Identification has been done for the X, Y, and Z DOF of the real system, and a prototype controller is on board the Galen Robot that has yet to be thoroughly tested. No work on the virtual fixtures has been attempted yet since the controller is not running. The stability analysis of the identified systems has been done, but they are not yet verified.
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 With the project in its current state, the software, development, design, and instructions are all well documented and available for review and reference. Future work will be done to complete the outstanding deliverables post spring 2023 semester until the beginning of 2023 summer.
-	Conclusion
-.1	Discussion
+**Discussion**
 Overall, the project is a success. We were able to accomplish a significant amount of work with only a few hands. I had the help of great mentors who helped streamline the project and direct me to the resources I needed. We succeeded in generating a working Admittance controller in the AMBF simulation that gives us the expected performance we would like with the real hardware. In addition to the controller in simulation, tools to connect the robot to AMBF and teleoperate the system with easily repeatable tools will now allow us to perform many different control tests faster and repeatably.
@@ Line 309: / Line 357: @@
 The control framework presented in the AMBF simulation is applicable to more robots than the Galen Robot. This MATLAB interface can be extended in use for any serial robot or other AMBF robots. The controller dynamics could easily be updated, the stability and transparency maps can similarly be calculated with these tools, and the admittance gains can simply be selected. This will make applying admittance controllers to any form of cobot relativley simple.
-While the controller has been verified in contact in the simulation, it still would be nice to have seen this on the real hardware. The efforts to do so are still on going, and the results have yet to be seen. We do anticipate the implementation of the controller to be promising.
+While the controller has been verified in contact in the simulation, it still would be nice to have seen this fully implemented on the real hardware. The efforts to do so are still on going, and the results have yet to be seen. We do anticipate the implementation of the controller to be promising as we have observed in the Z axis control on the Galen robot. With the full onboard admittance controller repeatable testing of the real hardware with the old controller and our new controller will allow us to capture results that show a measurable improvement.
-.2	Next Steps
+**Next Steps**
 Several next steps have been discussed throughout this report and will be summarized here again.
@@ Line 345: / Line 393: @@
     * {{:courses:456:2023:projects:456-2023-01:team01_final_checkpoint.pptx| Poster Teaser presentation}}
   * Project Final Presentation
-    * {{:courses:456:2023:projects:456-2023-01:final_poster_pdf.pdf|PDF of Poster}}
+    * {{:courses:456:2023:projects:456-2023-01:togac49_p_finalcis2poster.pdf.pdf|PDF of Poster}}
   * Project Final Report
-    * {{:courses:456:2023:projects:456-2023-01:final_report.pdf|Final Report}}
+    * {{:courses:456:2023:projects:456-2023-01:togac52_d_finalreport.pdf|Final Report}}
-    * links to any appendices or other material
   * Project Mentor's Report
+    * {{ :courses:456:2023:projects:456-2023-01:cis_2_project_mentors_report.pdf |Mentor's Report}}
 ======Project Bibliography=======
@@ Line 408: / Line 456: @@
 {{ :courses:456:2023:projects:456-2023-01:togac36_ambf_r_aydinstab.pdf?250 }}
+{{ :courses:456:2023:projects:456-2023-01:togac40_d_deltakin.pdf?250 }}
+{{ :courses:456:2023:projects:456-2023-01:togac50_ambf_in_admittancecontrolteleop.pdf?250 }}
+{{ :courses:456:2023:projects:456-2023-01:togac51_ambf_r_cartesiansystemidentification.pdf?250 }}

courses/456/2023/projects/456-2023-01/project-01.1683690355.txt.gz · Last modified: 2023/05/10 03:45 by bbanks15