Ackerman calculations for wheel angles #155
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Andrew-Lowitt
requested review from
AdityaKompella6,
Shreya1233 and
jinlin270
electrical/breakbeam.py
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| from enum import Enum | ||
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| def ackerman_calculations (steer_ang, left_ang, right_ang, outside_ang, inside_ang, track_width, wheel_base, steering_ration): |
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is there a reason this is in breakbeam.py?
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No, I must have forgot to switch branches when working on the break-beam
| def ackerman_calculations (steer_ang, left_ang, right_ang, outside_ang, inside_ang, track_width, wheel_base, steering_ration): | ||
| pass | ||
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| class Breakbeam: |
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breakbeam class changes not relevant to current pr; remove from current pr
engine/robot_logic/traversal.py
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| if not robot_state.is_sim: | ||
| robot_state.motor_controller.spin_motors(0, 0) | ||
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| def ackerman_calculations (left_ang, right_ang, inside_ang, wheel_base, |
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do we have specs for these functions?
engine/robot_logic/traversal.py
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| steering_ratio): | ||
| #calculate ideal wheel angle | ||
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| ackerman_percentage = 0 #This value needs to be determined by mechanical |
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can we document what this is?
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for that matter, what the other vars mean in this func
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Can we also make that a global variable since I assume it will stay constant
engine/robot_logic/traversal.py
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| track_width = wheel_base * ((1/np.tan(left_ang) - (1/np.tan(right_ang)))) | ||
| ackerman_ratio = (inside_ang / steering_ratio) | ||
| new_left_ang = 1/ np.tan((wheel_base * np.tan(ackerman_ratio)) / (wheel_base + (.5 * track_width )(np.tan(ackerman_ratio)))) |
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i dont believe tan^-1(x) = 1/tan(x)
engine/robot_logic/traversal.py
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| ackerman_ratio = (inside_ang / steering_ratio) | ||
| new_left_ang = 1/ np.tan((wheel_base * np.tan(ackerman_ratio)) / (wheel_base + (.5 * track_width )(np.tan(ackerman_ratio)))) | ||
| new_right_ang = 1/ np.tan((wheel_base * np.tan(ackerman_ratio)) / (wheel_base - (.5 * track_width )(np.tan(ackerman_ratio)))) | ||
| new_inside = new_left_ang #(change to new_right_ang based on above logic) ^ |
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is this accurate for both left and right turns?
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Yes, you resolve this based on the dependency of a left or right turn
engine/robot_logic/traversal.py
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| return [track_width, ackerman_ratio, new_left_ang, new_right_ang, new_inside, outside_ang] | ||
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| def parallel_ackerman_right (left_ang, right_ang, inside_ang, wheel_base, |
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for now, it might be a good idea to throw an error that the function is unimplemented
| FULL2 = 24 | ||
| # class BEAM_PINS(Enum): | ||
| # HALF1 = 17 | ||
| # HALF2 = 22 |
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You might want to remove this commented code if its not needed. It seems BEAM_PINS is in the class now so its not needed
engine/robot_logic/traversal.py
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| data = ackerman_calculations(left_ang, right_ang, inside_ang, wheel_base, | ||
| steering_ratio) | ||
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| #continue to implement |
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Maybe just raise an exception with a comment TODO so you know what parts need to be finished and if you run any test cases with this the exception will tell you you have to finish the function.
AdityaKompella6
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AdityaKompella6
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Overall Good Just some styling things I saw but the refactor seemed correct so it looks good.
jinlin270
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- Implemented the preliminary step in removing all hard-coded values from the break_beam sensors - The next part entails initializing the sensor with other values that are determined when the bucket/robot are starting a mission
- Created ackerman_calculations which calculates the needed angles to turn the wheels in order to turn - Still to implement: how to actually turn the wheels - What speed to rotate wheels/move - Rotate the wheels at the same time or different times?
…_left, turn_right
References
https://www.mathworks.com/help/vdynblks/ref/kinematicsteering.html
Summary
TLDR: Replace this with 1-3 sentence TLDR
Created the calculation function for Ackerman turning. This calculates the angles the wheel needs to turn in order to make turns to the right and left
Description
Implemented using the trig functions in multiple articles.
Still to implement:
How to actually turn the wheels, what speed to rotate the inner vs outer wheel.