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| − | {{TOC right}}
| + | #REDIRECT [[Kart]] |
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| − | The [[Kart|kart's]] stepper motor controller FPGA generates 4 coil driving signals and receives a ''stepper end'' input.
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| − | [[File:Kart stepper board.jpg|center|200px|stepper motor board]]
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| − | == Stepper motor ==
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| − | === Hardware ===
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| − | The stepper motor is a [http://en.nanotec.com/ Nanotec] [[Media:SP3575M0906-A.pdf|SP3575M0906-A]].
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| − | It has a step angle of 7.5°, and as such 48 steps per turn.
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| − | === Connector ===
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| − | The cables are connected as follows:
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| − | :{| cellpadding="4" cellspacing="0" border="1"
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| − | ! Signal
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| − | ! Color
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| − | |-
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| − | | phase 1
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| − | | white
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| − | |-
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| − | | phase 2
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| − | | blue
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| − | |-
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| − | | phase 3
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| − | | red
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| − | |-
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| − | | phase 4
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| − | | yellow
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| − | |-
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| − | | power
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| − | | brown, black
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| − | |}
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| − | == FPGA design ==
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| − | The stepper motor controller has to generate the 4 phases to turn the [[Kart|kart's]] steering wheels to the desired angle.
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| − | To begin with, the [[Kart#FPGA_Design|design environment]] has to be downloaded.
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| − | It comprises the <code>stepperMotorController</code> block contains the provided I2C bus interface
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| − | and an empty <code>angleControl</code> block which is to be designed.
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| − | === Functionality ===
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| − | The block receives a <code>target</code> unsigned number and has to step the coils at each occurrence of the <code>enStep</code> signal until the desired angle is reached.
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| − | The current in the coils is given by the 4 outputs <code>coil1</code> to <code>coil4</code>.
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| − | The steering angle, <code>actual</code>, is estimated with the help of a counter which increments or decrements each time when when the coil control signals change.
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| − | The block provides the estimated angle, <code>actual</code>, together with a logic signal, <code>reached</code>, telling if the desired angle has been reached.
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| − | === Zero position ===
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| − | A switch contact, providing the signal <code>stepperEnd</code>, has to be mechanically fitted on the kart in order set one end of the wheels' direction movement.
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| − | As soon as <code>stepperEnd</code> is activated, the stepper motor is stopped and the <code>actual</code> angle is reset.
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| − | With this, the steering motor will not try to turn further than what the kart's mechanical structure allows it to in one of the directions.
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| − | In the other direction, it is the programmer's task not to request a too large <code>target</code> angle.
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| − | This also means that the angles are always considered as positive numbers, the zero position being given by the <code>stepperEnd</code> switch.
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| − | {{TaskBox|content=
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| − | Draw the schematics of the <code>angleControl</code> block.
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| − | }}
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| − | {{WarningBox|content=
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| − | * In order to limit the current consumption, turn off the current in all the coils when the stepper motor is not turning any more.
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| − | * Make sure that both the first and the last pulse of the coil control signals have the same duration as all the others.
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| − | }}
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| − | === Hardware orientation ===
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| − | The mechanical design allows the following variations:
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| − | * the <code>stepperEnd</code> switch can be placed such as to detect the maximal steering angle either on the left or on the right side
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| − | * switching the coil controls in the sequence <code>1 - 2 - 3 - 4 - 1 - 2 - …</code> can result in the kart to turn either to the left or to the right
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| − | In order to cope with all possibilities, 2 setup signals are provided to the block:
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| − | * <code>sensorLeft</code> being '1' means that the <code>stepperEnd</code> switch has been placed such as to react when the wheels are oriented to the maximal steering angle on the left side
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| − | * <code>clockWise</code> being '1' means that the sequence <code>1 - 2 - 3 - 4 - 1 - 2 - …</code> lets the wheels turn to the right
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| − | The corresponding setup bits are configured in tty [[Kart/serial_link#Hardware_control_register|hardware control register]]
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| − | {{TaskBox|content=
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| − | Update the schematics of the <code>angleControl</code> block in order to cope for the different mechanical design possibilities.
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| − | }}
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| | [[Category:Kart]] | | [[Category:Kart]] |
