pxt-ev3/libs/chassis/chassis.ts

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enum ChassisProperty {
//% block="wheel radius (cm)"
WheelRadius,
//% block="base length (cm)"
BaseLength
}
namespace chassis {
/**
* A differential drive robot
*/
//% fixedInstances
export class Chassis {
// the motor pair
public motors: motors.SynchedMotorPair;
// the radius of the wheel (cm)
public wheelRadius: number;
// the distance between the wheels (cm)
public baseLength: number;
constructor() {
this.motors = motors.largeBC;
this.wheelRadius = 3;
this.baseLength = 12;
}
/**
* Makes a differential drive robot move with a given speed (cm/s) and rotation rate (deg/s)
* using a unicycle model.
* @param speed speed of the center point between motors, eg: 10
* @param rotationSpeed rotation of the robot around the center point, eg: 30
*/
//% blockId=motorDrive block="drive %chassis|at %speed|cm/s|turning %rotationSpeed|deg/s"
//% inlineInputMode=inline
//% weight=99 blockGap=8
drive(speed: number, rotationSpeed: number) {
this.driveFor(speed, rotationSpeed, 0, MoveUnit.Degrees);
}
/**
* Makes a differential drive robot move with a given speed (cm/s) and rotation rate (deg/s)
* using a unicycle model.
* @param speed speed of the center point between motors, eg: 10
* @param rotationSpeed rotation of the robot around the center point, eg: 30
* @param value the amount of movement, eg: 2
* @param unit
*/
//% blockId=motorDriveFor block="drive %chassis|at %speed|cm/s|turning %rotationSpeed|deg/s|for %value|%unit"
//% inlineInputMode=inline
//% weight=95 blockGap=8
driveFor(speed: number, rotationSpeed: number, value: number, unit: MoveUnit) {
// speed is expressed in %
const R = this.wheelRadius; // cm
const L = this.baseLength; // cm
const PI = 3.14;
const maxw = 170 / 60 * 2 * PI; // rad / s
const maxv = maxw * R; // cm / s
// speed is cm / s
const v = speed; // cm / s
const w = rotationSpeed / 360 * 2 * PI; // rad / s
const vr = (2 * v + w * L) / (2 * R); // rad / s
const vl = (2 * v - w * L) / (2 * R); // rad / s
const sr = vr / maxw * 100; // %
const sl = vl / maxw * 100; // %
this.motors.tankFor(sr, sl, value, unit)
}
/**
* Sets a property of the robot
* @param property the property to set
* @param value the value to set
*/
//% blockId=chassisSetProperty block="set %chassis|%property|to %value"
//% blockGap=8
//% weight=10
setProperty(property: ChassisProperty, value: number) {
switch (property) {
case ChassisProperty.WheelRadius:
this.wheelRadius = Math.max(0.1, value); break;
case ChassisProperty.BaseLength:
this.baseLength = Math.max(0.1, value); break;
}
}
/**
* Sets the motors used by the chassis, default is B+C
* @param motors
*/
//% blockId=chassisSetMotors block="set %chassis|motors to %motors"
//% weight=10
setMotors(motors: motors.SynchedMotorPair) {
this.motors = motors;
}
}
//% fixedInstance whenUsed
export const chassis = new Chassis();
}