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Constraint Validation
Listed below are key metrics that must be measured to ensure our design means competition requirements. This data may help with improving designs, but mainly is intended to verify constraint conformity. These tests will require no support from software, firmware or electrical.
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The mass of each of the following items should be recorded: Description | Measured Mass (kg) |
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title | Chassis (MR22-DT-A0014) |
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| 7.10 | Expand |
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title | Differential Bar (MR22-DT-A0007) |
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| 1.40 | Expand |
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title | Suspension Bar (MR22-DT-A0015) |
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| *Weigh and record each suspension bar separately |
| 2.25 | Expand |
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title | Wheel Module (MR22-DT-A0030) |
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| *Weigh and record each wheel module separately |
| 3.05 | Expand |
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title | Electrical Box (MR21-EB-B-Ahu) |
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| *Weigh ebox with all interior components (fan, jetson, odrives, etc) and wiring *Ensure that proper adapters are installed |
| 2.30 (Empty) | Expand |
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title | Battery Pack (P/N TBD) |
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| To be revised when proper battery pack is selected. In mean time, measure, weigh, photograph and document whatever battery solution is installed on rover |
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title | Full Drivetrain Assembly |
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| Measure and weigh a fully functional drivetrain (no gimbal, all components described above installed, wired and functional) |
| 33.5 |
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The overall dimensions of the drivetrain should be recorded. Competition Constraint: Drivetrain must fit in a 1.2m cube Image Added | Image Added |
Measured Length: 1.16m Measured Width: 1.18m Measured Height:
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Test DetailsFully assemble a functional drivetrain (drivetrain, EMPTY ebox, wheel assemblies, battery pack, no gimbal) Drop assembly from 1m height Observe any mechanical failures, failed wire connections, broken components, etc. Determine if drivetrain prototype is capable of being controlled at the same efficacy before and after drop Take video footage of drop with slo motion camera (phone camera is probably OK, just frame the video from multiple angles)
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Power Performance Testing
Listed below are tests designed to quantify and understand the motor performance of our drivetrain. These metrics are intended to provide hard data on basic electro-mechanical performance of the drivetrain, and is mainly intended to validate the following items:
motor spec’ing calculations and assumptions
power draw estimations
basic driving functionality
These tests will require electrical and firmware support, as well as odrive functionality and basic software to perform the following functions:
Independent and simultaneous control of all 6 wheel assemblies (on/off, and direction control)
Motor speed control
Logging of motor RPM, current and voltage (recording PWM cycling), preferably in CSV format
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title | No Load Current Draw |
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Test DetailsLabel each wheel module with a number (1-6). Stick this label directly on the wheel module somewhere it will not fall off Spin an unloaded wheel assembly off of nominal voltage (no PWM) and record current via multimeter over an average of 30s steady state current draw Wheel assembly should be suspended in air (no physical load on wheels) Collect current draw for each wheel / motor assy Repeat for forward / reverse wheel driving Take a picture of the physical testing setup
Test PurposeThis is a very useful test to vet out the following data points Baseline wheel assembly efficiency Determine assembly variability (poorly assembled wheel assy can draw more current / have higher current variability) Current should not vary based off of rotational direction, so collecting data to verify this fact is useful
Required HardwareWheel Module | Average Forward Current (A) | Average Reverse Current (A) |
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1 | | | 2 | | | 3 | | | 4 | | | 5 | | | 6 | | |
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title | Basic Terrain Straight Line and Drive Speed Testing |
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Test DetailsUse the same labels on the wheel modules as specified in the previous test. In a diagram, identify which wheel corresponds to which number. Record weight of total moving system prior to collecting any data Mark a start/finish point on the main bay floor of a known distance (i.e. 5m), Power all 6 wheels forward with nominal operating voltage simultaneously Record the time it takes to complete the known distance of travel (with physical stopwatch, rough physical estimation) using timer, iphone video, it doesn’t really matter Record encoder estimated RPMs for all wheels during test (CSV format preferred) Record current going into each wheel on each test (CSV format preferred) Take a video (from multiple angles) of the rover driving through this runway Repeat this test 3 times Image AddedTest PurposeThis is a very useful test to determine the following: What is our motor performance on basic terrain (current, motor RPM)? The floor in the bay is flat and smooth, and should represent the easiest driving conditions imaginable How poor is our straight line performance without PID? In an ideal world, all wheels should have the same efficiency and floor speed and the rover should go straight without any PID. This is very unlikely to happen, but it would be good to see how far off we are for a reference point
Are our encoders properly calibrated? We can compare the physical drive speed to the encoder recorded wheel speeds to determine if there is any variability between these data points
Required HardwareIf the odrives are tested and ready to use: Battery Pack Odrives Input from other leads
If odrives are still being tested / verified, we should be able to do this with just power supply, long extension cable and arduino setup. Motors can be controlled simultaenously off of one channel of the power supply connect current sensors to each of the motors which are hooked up to analog pins on an arduino encoder outputs connected to digital pins on arduino no PWM control on motor (nominal voltages only)
Metric | Test 1 | Test 2 | Test 3 |
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Overall Weight (kg) | | | | Measured Rover Speed (m/s) | | | | Wheel 1 Speed (m/s) | | | | Wheel 1 Current (A) | | | | Wheel 2 Speed (m/s) | | | | Wheel 2 Current (A) | | | | Wheel 3 Speed (m/s) | | | | Wheel 3 Current (A) | | | | Wheel 4 Speed (m/s) | | | | Wheel 4 Current (A) | | | | Wheel 5 Speed (m/s) | | | | Wheel 5 Current (A) | | | | Wheel 6 Speed (m/s) | | | | Wheel 6 Current (A) | | | |
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Competition Performance Testing
Listed below are tests designed to get a good understanding of how our drivetrain will perform at competition. This section will be revisited after the first set of testing is completed. For more details, please contact Austin Tailon Huang .