wb = xlsx_package.workbook
wb.add_worksheet(name: "Reporte") do |sheet|
    sheet.add_row ["Grupo", @vehicle.group.name]
    sheet.add_row ["Vehiculo", @vehicle.name]
    sheet.add_row ["", ""]
    sheet.add_row ["", ""]
    sheet.add_row ["Fecha", "Velocidad", 'Ubicación']
    @positions.each do |position|
        sheet.add_row [position.fixtime, position.speed, position.gm_link]
    end
end