function speedChange_callback(ui,id,newVal)
    speed=minMaxSpeed[1]+(minMaxSpeed[2]-minMaxSpeed[1])*newVal/100
end

function sysCall_init()
    -- This is executed exactly once, the first time this script is executed
    bubbleRobBase=sim.getObjectAssociatedWithScript(sim.handle_self) -- this is bubbleRob's handle
    leftMotor=sim.getObjectHandle("bubbleRob_leftMotor") -- Handle of the left motor
    rightMotor=sim.getObjectHandle("bubbleRob_rightMotor") -- Handle of the right motor
    noseSensor=sim.getObjectHandle("bubbleRob_sensingNose") -- Handle of the proximity sensor
    rightSensor=sim.getObjectHandle("bubbleRob_rightSensor") -- Handle of the right sensor
    leftSensor=sim.getObjectHandle("bubbleRob_leftSensor") -- Handle of the left sensor
    minMaxSpeed={50*math.pi/180,300*math.pi/180} -- Min and max speeds for each motor
    backUntilTime=-1 -- Tells whether bubbleRob is in forward or backward mode
    -- Create the custom UI:
        xml = '<ui title="'..sim.getObjectName(bubbleRobBase)..' speed" closeable="false" resizeable="false" activate="false">'..[[
        <hslider minimum="0" maximum="100" onchange="speedChange_callback" id="1"/>
        <label text="" style="* {margin-left: 300px;}"/>
        </ui>
        ]]
    ui=simUI.create(xml)
    speed=(minMaxSpeed[1]+minMaxSpeed[2])*0.5
    simUI.setSliderValue(ui,1,100*(speed-minMaxSpeed[1])/(minMaxSpeed[2]-minMaxSpeed[1]))
end

function sysCall_actuation()
    result=sim.readProximitySensor(noseSensor) -- Read the proximity sensor

    debrisRight=sim.readProximitySensor(rightSensor)
    debrisLeft=sim.readProximitySensor(leftSensor)

    if (debrisRight>0) then
        sim.setJointTargetVelocity(rightMotor,0)
        sim.setJointTargetVelocity(leftMotor,speed/2)
    end
    if (debrisLeft>0) then
        sim.setJointTargetVelocity(leftMotor,0)
        sim.setJointTargetVelocity(rightMotor,speed/2)
    end
    -- If we detected something, we set the backward mode:
    if (result>0) then backUntilTime=sim.getSimulationTime()+5 end

    if (backUntilTime<sim.getSimulationTime()) then
        -- When in forward mode, we simply move forward at the desired speed
        sim.setJointTargetVelocity(leftMotor,speed)
        sim.setJointTargetVelocity(rightMotor,speed)
    else
        -- When in backward mode, we simply backup in a curve at reduced speed
        sim.setJointTargetVelocity(leftMotor,-speed/2)
        sim.setJointTargetVelocity(rightMotor,-speed/8)
    end
end


function sysCall_cleanup()
    simUI.destroy(ui)
end