https://www.rocketsandrigs.com/blog daily 0.75 2021-04-10 https://www.rocketsandrigs.com/blog/kalman-filter-2 monthly 0.5 2021-08-17 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629171298988-FICBIAAGB4XJUPFT4AXS/badQ.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629171438628-RKGSYOHK3NWZ6YFSRCIC/Qscaling.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1628959996203-QCJ4C2BNLK1YJ43PIFPG/covariance+values.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629171115823-CBJVH06LKGUZ7FRFF5CF/wrongH.png Blog - Kalman Filter Pt. 2 - Make it stand out Incorrect H-function leads to possibly the worst Kalman filter. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629171867850-BGGYLLS68UKWX2GJK3J2/residualCheck.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629172667671-Q9RE96UYUTQ4TPX9NBN9/IMG-4626.jpg Blog - Kalman Filter Pt. 2 - Make it stand out Truck on desktop test stand https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1628960479134-5PUUDZPMSO7JRXUCKUOU/State+transition.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629171700955-NYSW95W6O2WG5CJ0M5QA/staticDT.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1629172642228-OD7ZH71V4RAYI14WRWAY/IMG-4625.jpg Blog - Kalman Filter Pt. 2 - Make it stand out Motor speed encoder https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1628959394842-VI7HH59MAXWBOFKBNQR7/state+variable.png Blog - Kalman Filter Pt. 2 - Make it stand out Whatever it is, the way you tell your story online can make all the difference. https://www.rocketsandrigs.com/blog/rc-truck-differential-mkii monthly 0.5 2021-05-06 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271792809-IV4MEK0THDI3JDAY9C06/ideal+gear.png Blog - RC Truck Differential MkII Ideal gear meshing with no backlash https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271855889-EPZ9HJXCAGT42D9ZSOS0/backlash+-+narrow+teeth.png Blog - RC Truck Differential MkII https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620272658848-BVNMNW7GXT2W86K8GD1D/differential+case.png Blog - RC Truck Differential MkII https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620272560066-T9DUCKQB3BZHXGFP45LM/suspension+on+rock.png Blog - RC Truck Differential MkII https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271707298-N4DIDO3JS2WRQSUR2E3P/new+spider+with+pinion.png Blog - RC Truck Differential MkII New design with a more rigid central case https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620272589586-PS38HP08B7SFRR9O9TCT/new+suspension+mounting.png Blog - RC Truck Differential MkII https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620272775817-83M5Z4N8J2M9JE6FUQGB/kinematic+constraints.png Blog - RC Truck Differential MkII https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271825447-WKGFNA9VIE7PKUG5YOKA/backlash+-+mounting+distance.png Blog - RC Truck Differential MkII Backlash via adjusted mounting distance https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271449870-7DA062JHYYNIPRV6NLAK/walking+beam.png Blog - RC Truck Differential MkII Walking beam suspension https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271646597-I00KLG9ULWHANUWAQZY0/old+spider+with+pinion.png Blog - RC Truck Differential MkII Previous design with simplified spider gear constraints https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271398329-6W1CIJR2YYZ0JXPNOIWQ/camelback+suspension.png Blog - RC Truck Differential MkII Camel back suspension https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1620271486684-3QJ2N22YSN5J0KJAP631/air+ride.png Blog - RC Truck Differential MkII Air ride suspension The last major update for the suspension is to incorporate some kinematic restraints in order to restrict the movement of suspension and axles with respect to the chassis. The previous designs were more or less rigid connections with no real suspension. This was fine initially, but as the design has expanded, the constraints become a necessary component for the axles and drive train to function properly. https://www.rocketsandrigs.com/blog/angular-speed-encoder monthly 0.5 2021-04-13 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618281531841-3Q7KHJBAVYBU6UW3NRJG/encodersPrinted.jpg Blog - Angular Speed Sensor https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618166338344-ZEADHWJMYXEV3WLL4SLM/raw.png.png Blog - Angular Speed Sensor https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618279769366-6SKNSTLLIC04GMBQN3MS/mechanical.png Blog - Angular Speed Sensor A purely mechanical tachometer used to be a common solution in vehicles. The principal of operation relies on the flyball governor, originally used for speed control on steam engines! https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618281166281-7V60VEML4ASCXJVBA7HB/encoderDesigns.png Blog - Angular Speed Sensor There are two main designs I tried for this experiment. One design embedded magnets into the wheel and utilizes a simple hall effect sensor. This sensor output is nominally high and drops low in the presence of a magnetic field. The light gate design uses a common IR emitter-detector pair with regularly spaced slots in the wheel. Examples of the printed designs are below. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618280076095-KPIF18XT21S553RTOCD6/hardwareCounter.png Blog - Angular Speed Sensor This design uses a hardware-based, pulse counting strategy. In this case, the number of pulses per revolution is known, the sampling time is fixed or at least can be measured. The microcontroller or single board computer can periodically read the value from the counter, divide by the time between readings, and voila - rotational speed. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618279902080-66REF6744R0VFYXJIRZJ/analog.png Blog - Angular Speed Sensor There are numerous designs which can generate a voltage which scales with the rotational speed. This is often done using some form of magnets and coil windings. The voltage can be read and converted by an analog-to-digital converter. The scaling needs to be calibrated in the software. There are a number of difficulties with this design from the “cleanliness” of the reference voltage to limitations on the precision of the ADC. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618280368038-78U5T98L6Y0FJFMX92R5/softwareCounter.png Blog - Angular Speed Sensor The last case is the one used in this project. It’s very similar to the pulse counting method except in this case, the uC or SBC uses software interrupts attached to a hardware pin to count up the number of ticks and calculate the speed. The downside here of course is the dependence on the software to do the work. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1618166570891-M7T8C94K189Z3XOHBPUQ/averaged+noise.png Blog - Angular Speed Sensor https://www.rocketsandrigs.com/blog/the-food-winch-part-iii monthly 0.5 2020-08-12 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1597015114188-SP5WQLIXWJWR25F62LL8/Practical+Trajectory.png Blog - The Food Winch - Part III A more practical representation of the optimal speed profile https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1597201194686-NWO0DRSR1N1G6645QTB1/peak_acceleration.png Blog - The Food Winch - Part III Plot of the equation above for peak speed as a function of acceleration capability. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1597014247944-E07KRA4Y20HJ6TAA67M5/Fastest+Speed+Profile.png Blog - The Food Winch - Part III Speed over time for the fastest, deceleration limited bucket raise https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1597016114401-4PH2DF8XIRLYU02JX51R/Peak+Speed+Derivation.png Blog - The Food Winch - Part III Peak speed for an assumed acceleration capability. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1597014569052-18Y4B7L1V8E693KK6FE3/Min+time+-+max+speed.png Blog - The Food Winch - Part III Derivation of min time and peak speed. https://www.rocketsandrigs.com/blog/the-food-winch-part-ii monthly 0.5 2020-08-06 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1596078736702-2RVCH4J31UK74N5TVAEQ/Mechanical+EOM.png Blog - The Food Winch - Part II Equations of motion for gear-a and gear-b from the overall diagram https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1596077795500-3XWMMDWK0RKWZY0PJBHX/Dynamics+Model.png Blog - The Food Winch - Part II System diagram, coordinates, reference frames, and forces https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1596081879779-KTJ65TBAGWT5BTDXOFO1/worm+gear+open+loop.png Blog - The Food Winch - Part II https://www.rocketsandrigs.com/blog/the-food-winch-part-i monthly 0.5 2020-07-30 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1595303226953-Z5QZV87KKJE19X1S13VK/System+Model+-+Building.png Blog - The Food Winch - Part I Simple view of the planned system and idea. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1595304047091-T28EXRNWV264ZRH7DEMC/Motor+EOM.png Blog - The Food Winch - Part I https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1595304893950-CFN7TSO501GCDT6JUIOG/System+Model+-+Drivetrain.png Blog - The Food Winch - Part I Simplified drive train diagram. https://www.rocketsandrigs.com/blog/3d-printed-springs-part-ii monthly 0.5 2020-05-01 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1587839675274-46JLMRTJI99OIOX59FH1/Spring+Rate+v.+Layer+Spacing.png Blog - 3D Printed Springs - Part II A cubic fit! https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1587837913078-0ZTBX0D0N57UCJFBOOF5/Spring+Stiffness+v.+Width.png Blog - 3D Printed Springs - Part II The spring stiffness appears to be a linear function of the overall width https://www.rocketsandrigs.com/blog/work-from-home-ergonomic-improvements monthly 0.5 2020-04-24 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1587699646963-9V0MY7UKF4V4EW07CDNC/IMG-2013.jpg Blog - Work from Home - Ergonomic Improvements https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1587699569497-R6HW4PH6ODTRTIVYGS50/IMG-1893.jpg Blog - Work from Home - Ergonomic Improvements https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1587699953095-5N0GU8NL1TW3OS1ITZGJ/60876969064--9132C9E0-DF92-4119-AA32-28A6FB5A8749.JPG Blog - Work from Home - Ergonomic Improvements The final version quickly put to use! https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1587699981433-2NU7K9I08KKR8AJNAOOL/60876964045--19C20F77-9445-40BE-8C93-6A4B333A2D41.JPG Blog - Work from Home - Ergonomic Improvements https://www.rocketsandrigs.com/blog/the-kalman-filter monthly 0.5 2020-04-12 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586725142925-4IJN4IAKNCFN6JI9DLUC/motor_saturation.png Blog - A Simple Kalman Filter in Practice - Part 1 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586714595555-AWAH57ZKZDBEAEE54FO7/measurement_noise.png Blog - A Simple Kalman Filter in Practice - Part 1 Motor Speed Variance as a function of throttle https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586724295524-NPLZ5334RBAPPU32BIPN/linear_motor_model.png Blog - A Simple Kalman Filter in Practice - Part 1 rpm = throttle * 30,655 - 1,981 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586714392793-Q1G9KHIYO0G1WRCZVS5P/dc_motor_model.png Blog - A Simple Kalman Filter in Practice - Part 1 DC Motor Model: rpm as a function of motor throttle rpm = throttle * 30,848 - 1,629 slope: 30,848 (+/- 120.9) intercept: -1,629 (+/- 93.2) https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586727108770-TAOLTKIUEI0KXWB5YRKI/ticks_10v20.png Blog - A Simple Kalman Filter in Practice - Part 1 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586718004930-58Q2SEKI81EKP11Q5822/ee_setup.png Blog - A Simple Kalman Filter in Practice - Part 1 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586716636774-SJ5HIUCF33HEQSQ97750/motor_encoder.jpg Blog - A Simple Kalman Filter in Practice - Part 1 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586729657543-RHF97I9AAZI0BRHVUKM1/kf_results.png Blog - A Simple Kalman Filter in Practice - Part 1 Kalman Filter results with step inputs https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1586725642575-T27VTLPOVK1PM82B019T/steps.png Blog - A Simple Kalman Filter in Practice - Part 1 https://www.rocketsandrigs.com/blog/3d-printed-springs monthly 0.5 2020-03-29 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1585499075003-NJ4MPN2KC334KUKDN5JR/spring+rate.png Blog - 3D Printed Springs - Part 1 Here we see a highly non-linear relationship, when considering the stiffness as a function of width. R^2 = 0.986 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1585500467486-0410E7FVUHDDWIHFHKGJ/Test+Fixture.jpg Blog - 3D Printed Springs - Part 1 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1585499050288-8FVB9EFIHPFVUID8K2ME/displacement+vs+loading.png Blog - 3D Printed Springs - Part 1 The widest spring appears to be the stiffest https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1585501098698-MOSJIC71N3ANJ2I3HXUR/Spring+Drawing.PNG Blog - 3D Printed Springs - Part 1 https://www.rocketsandrigs.com/blog/category/Travel monthly 0.5 https://www.rocketsandrigs.com/blog/category/Relationships monthly 0.5 https://www.rocketsandrigs.com/blog/category/Health monthly 0.5 https://www.rocketsandrigs.com/blog/category/Culture monthly 0.5 https://www.rocketsandrigs.com/blog/category/Sports monthly 0.5 https://www.rocketsandrigs.com/about daily 0.75 2020-03-29 https://www.rocketsandrigs.com/home daily 1.0 2020-02-20 https://www.rocketsandrigs.com/donate daily 0.75 2025-05-09 https://www.rocketsandrigs.com/projects daily 0.75 2020-05-17 https://www.rocketsandrigs.com/projects/air-rocekts monthly 0.5 2020-05-17 https://www.rocketsandrigs.com/projects/3dp-semi-truck monthly 0.5 2020-05-17 https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1589752653214-84SQPXL4A51QXJ72I7XU/IMG-1389.jpg Projects - 3D Printed Semi-Truck https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1589753104014-86H3TRDHOVDMDNYRP52C/59522734139--5D089BE4-50C0-490F-A974-BAE191719C03.jpg Projects - 3D Printed Semi-Truck - Steering System The front steering system is only actuated on the driver side via the Pitman arm from the steering servo. In order to actuate the passenger side tire, the steering spindle are connected via a ball-joint tie-rod. The wheel end assemblies capture some skateboard bearings and use m3 bolts as functional lug nuts. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1589752253825-NLIRT8UQ81WIKO6T7KTF/IMG-1350.jpg Projects - 3D Printed Semi-Truck - Steering Gear The steering system is configured as a Pitman-arm, drag-link configuration. These have been used in vehicles of the early 20th century for their simplicity, high mechanical advantage, and robustness. They’re still the primary steering design for semi-trucks today! https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1589754353892-XZZH8DV02JF5LA1XH6OR/File_001.png Projects - 3D Printed Semi-Truck - Software In order to get the vehicle to drive like a full scale truck would, there are some artificial limitations placed on the response of the vehicle. For example, if hitting the gas at full throttle, the small dc motor can accelerate the truck way faster than in reality. Instead, the simulation estimates how a real truck would response, scales down the values based on size of the toy truck and uses a basic feedback controller to keep the toy matching the target values. Future features include gear shifting, coasting, engine brakes, and other fun aspects of full-size trucks. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1589753433578-P2RZQ46I9ZUHHZXAQRUU/IMG-2241.jpg Projects - 3D Printed Semi-Truck - Tandem Differentials The truck is configured as a 6x4 - that is a vehicle with 3 total axles and two of them driven. In order to improve the general drive ability, the differentials allow the truck to turn without scrubbing the tires. The differentials use a spiral bevel gear configuration with lots (10) bearings per differential to keep them running smoothly! The ratio of the pinion-ring gear pair is 2:1, giving the powertrain a final mechanical advantage of approximately 20:1. https://images.squarespace-cdn.com/content/v1/5e4e162c844fc744d0656668/1589752620802-D36CPBOG7920XV47V9QG/IMG-2240.jpg Projects - 3D Printed Semi-Truck - Gearbox This is a simple gearbox with a total mechanical advantage of 9.4:1. The gearing is designed to reduce the motor speed to keep the top speed of the motor close to the scaled max speed for a truck driving at highway speeds, around 65 mi/hr (~30 m/s).