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JMC – Joint Motion JMC – Joint Motion Controller Controller Complete guide to Complete guide to building and testing each building and testing each JMC JMC

JMC – Joint Motion Controller Complete guide to building and testing each JMC

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Text of JMC – Joint Motion Controller Complete guide to building and testing each JMC

  • JMC Joint Motion ControllerComplete guide to building and testing each JMC

  • 2 channel 24v Motor ControllerThe motor controller is a flash programmable, compact servo driver that can be used for all of the power axes on the hubo. The amplifier stage contains the power electronics like the MOSFETs, filter capacitors, and current sensors.On the controller board, The Controller Area Network interface connects to the main computer, converting drive commands into servo output. The controller board reads the motor encoder and uses a PD loop for position control.

  • Soldering the PCBThe density of parts and complexity of these circuits means that soldering and assembly has to be correct the first time. A good order to solder part is:

    Large, dense chips such as quad-flat packComponents with pads underneath the part that require a lot of room to reachChip resistors, capacitors, and diodes by size: By only soldering one kind of part at a time, the chance of choosing the wrong one accidentally is reduced. Bulky components such as radial capacitors, MOSFETS, DC-DC converters, inductors, etc.Headers and connectors411333554551143

  • Check Solder JointsBad JointsLook tarnished or dirtyLack solderHave a bubble-like appearanceparts crooked or tiltedhave solder whiskers or bridges between pins

    Pictures for each point (coming soon)

  • Check Solder JointsGood JointsHave even distribution of new solderLook shiny and cleanAre aligned with the padsHave distinct edges

    Pictures for each point (coming soon)

  • ConnectorsConnector layoutEncoder for Motor 1 (8 pins)Encoder for Motor 2 (8 pins)Pot 1 (ignore)Pot 2 (ignore)CAN Bus (2 pins)24V12V (do NOT plug 24V here)Motor 1Motor 2

  • MotorsThe leg joints use 90W and 400W motors to drive each of the 6 axes. Brush DC motors were chosen for their efficiency, as well as the simplicity of the controller.For testing, the rack of motors is connected to the motor driver outputs. An embedded computer identical to that in the HUBO sends test commands to each axis, verifying that the joint motion is accurate.

  • CAN Bus Operation2 wire differential signalAddress built into the signal to allow multiple devices on a common busNRZ data transmission (similar to RS232)(need to research further, w/ diagrams)

  • Testing ProcedureIn this section is the complete procedure for testing a board

  • Flash ProgrammingOpen Codewarrior IDE for Motorola processorsOpen file C:\Metrowerks_work\KHR_3_ALPHA\JMCxx\motor.mcpConnect BDM (6 pins) to controller board, tilting it in the socket to contact all 6 pins (fiddle with this if necessary to get a good connection)Run Debugger (4th button) while BDM is connected (i.e. hold the connector in place with your finger)

  • Flash ProgrammingUnder the ICD Menu, choose Flash to bring up the flash programming window. Select the FLASHC000 (and ONLY that one) and press Erase to clear the memory of old programs. Load the new flash program in folder \bin\motor.absHit Reset Target, ignore the warning, and disconnect the BDM cable

  • Operating the Power supplyThe power distribution board connects to either the hubo's batteries or an external power supply. It delivers +/- 12V, 24V and 5V to the motor controllers and sensors.Switches 1 and 3 are computer power; Dont touch during OperationSwitch 2 toggles power to the controller (12V)Switch 7 controls power to the sensors (encoder, F/T)Switches 4,5, and 6 are not used in this test

  • The Power Bus

    12VGND24VGND12VGND24VGND12VGND-12V-

  • Joint Axis TestingTurn Power Supply OFFConnect 24V, 12V, Motor 1, Motor 2, Encoder 1, Encoder 2, CAN Bus as shownLoad Startrack Test programAfter verifying connections, turn on Power supplyPress START to connect to CAN and begin issuing commands

  • EncodersPress CONTROL OFF to shut off power to the motors (for safety)Press Encoder Zero to reset encoder valuesPress Read Encoder to bring up the encoder data screen.While manually turning the servomotor, you should see the connected encoders readout change

  • Power TestsPress Open Loop TestEnter a value in the speed textboxPress RUN and verify motor is turning.Press Motor Position ControlEnter a position for motor to seek and press Run

  • Future AdditionsTroubleshooting a non-functional boardSchematics and functional diagramsF/T sensor assembly (strain), F/T signal conditioner (there are no spares currently, so I need to wait for this part)Connecting and operating the booster amplifier for the hip joint