This picture considers a simple quasi-adaptive constrained control strategy that can be used for fin, rudder, or combined fin-rudder stabilizers. The strategy estimates the parameters of a linear output disturbance model for the wave induced roll motion using roll and roll rate measurements taken before closing the control loop. This model is then used to implement a constrained predictive control strategy. The strategy can thus be adaptive with respect to changes in the sea state and sailing conditions. The work also explores the benefit of penalizing roll accelerations as well as roll angle in the associated cost.In a previous work, we have proposed the use of constrained model predictive control (MPC) to
address the control system design problem forfin and/or rudder-based stabilizers- see Perez etal. (2000) and Perez and Goodwin (2003). This approach offers a unified framework for minimizing the impact of roll motion on ship performance,handling input and output constraints and
also provides a means for implementing adaptive
strategies.In order to implement the proposed MPC strategy,
two models are necessary: a model describing the dynamic behavior of ship motion due to control action (rudder and/or fins) and a model describing the wave induced roll motion. The first model can be obtained using system identification
techniques together with tests performed in calm waters-see, for example, Zhou et al. (1994). This model should be updated for different ship speeds. The wave induced roll motion can be modelled using a second order shaping filter, which is then
used to predict the wave induced roll motion in the MPC Formulation. This model cannot be es timated before hand since it depends on the sea state and sailing conditions (speed and encounter angle.) Adaptation is necessary.
The purpose of this paper is twofold. First, to propose a simple way to estimate the parameters of the wave-induced roll model; and thus, extend our previous work. Second, to incorporate a penalty on the roll acceleration in the associated cost. The effect of roll acceleration on ship performance has long been recognized in the naval
environment (Warhurst, 1969). Nonetheless, direct roll acceleration reduction has often been omitted from
stabilizer control system design in literature and
reported practical implementations. is shown in Figure 1. Because the control will be ultimately implemented on a computer, we will adopt a discrete-time framework to describe the models and control system design problem.
In many business organizations, there is still much confusion about the role of strategic brand development and brand management and who within the organization should lead it.
Brand strategy and brand management is too important to be left to marketing people. That’s my spin on the famous David Packard quote (as in Hewlett Packard) about marketing being too important an activity to the well-being of a business enterprise to be left in the hands of marketing people alone.
Business leaders have notoriously looked at marketing with a critical eye. Marketing is not a “hard discipline” like engineering, sales and finance. Business leaders love quantified activities that facilitate a predictable return. Marketing doesn’t provide predictable returns. And in today’s social media, permission and privacy driven world, marketing is even more suspect by consumers. Customers want real, authentic connections and engagement to brands, not more marketing and selling. Brand strategy and brand management is not a sub-discipline of marketing. As brand strategy and brand management becomes more essential for marketplace success, enlightened business leaders have moved it further away (and upstream) from the core competencies within marketing organizations. Yet for many organizations, brand strategy and brand management is an activity mostly managed within the marketing discipline. Consequently everybody in the marketing profession does “branding” these days. Branding gets bundled into a plethora of tactical marketing activities like PR, advertising, social media, sales promotion, packaging and marketing communications. Brand strategy and brand management is not marketing, advertising or communications. This by no means diminishes the essential role of marketing for creating awareness and demand. Brand strategy and brand management is not about creating awareness, it’s about guiding the quality and relevance of organizational behavior in serving a specific group of customers/consumers. It’s a more sacred and strategic process defining the who, the what, and why an organization or a product exists in the first place – beyond money making. Brand strategy and brand management is about the soul of the thing–the intangible, the unseen, the meaning rather than the physical. Brands make promises to people. Break the sacred promise and no amount of clever marketing will rebuild lost trust. Just ask Netflix or Tropicana what can happen to your business when the bonds of trust breaks. The value of brands lies in the perception customers have in their minds about what makes a brand matter to them. To matter nowadays, requires brands build deeply rooted emotional connections and never fail to deliver on the promise. The discipline of brand strategy and brand management is centered in creating a set of unchanging, universal principles that guides the behavior of organizations and the products they bring to the marketplace over the life of the enterprise. It’s not about informing the next advertising campaign. Brand strategy and brand management is a top down discipline. The principles that guide the strategy and management of a brand have to be driven by the leadership of the organization. Brand leadership begins with business leadership. Business strategy informs brand strategy which, in turn, informs marketing tactics. When marketing organizations (or worse their advertising agencies) attempt to define and lead brand strategy, it becomes more marketing. Consumers / customers loathe marketing. Marketing now gets in the way of real engagement with a brand. Marketing needs to be baked into brand strategy, not the other way around. Business leaders must drive brand strategy. Leaders determine the higher purpose, vision and values of the business enterprise, not their marketing organizations. Consequently, when leaders have clarity on “why” their brand exists, it’s much easier and more effective to weave the elements of brand strategy into the fabric of the organizational culture and guide the behavior of the organization at every customer touch point in the value chain. Brand strategy and brand management is internal, marketing is external. Brand strategy informs everyone within the organization why they exist and matter to people, what values they share, what markets they serve, what products they innovate and bring to market, what processes they use, and what experiences they are to create for customers and the community at large. Without this solid foundation firmly established, marketing organizations (and their agency partners) have nothing to go on – no map, no guidance, and no discipline – an aimless ship adrift without a rudder. Brand strategy and brand management is the rudder that steers the ship. This today’s picture continues to have to make do with fewer resources to accomplish more
objectives. Competition for scare resources is an annual statistic challenge. To work without an effective formal strategy is to sail without a rudder 🙂 A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull (watercraft) or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft’s stern, tail, or after end. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may be used to link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics.
Chinese naval developments occurred far earlier than similar western technology.
The first recorded use of rudder technology in the West was in 1180. Chinese pottery models of sophisticated slung axial rudders (enabling the rudder to be lifted in shallow waters) dating from the 1st century have been found. Early rudder technology (c 100 AD) also included the easier to use balanced rudder (where part of the blade was in front of the steering post), first adopted by England in 1843 – some 1700 years later. In another naval development, fenestrated rudders were common on Chinese ships by the 13th century which were not introduced to the west until 1901. Fenestration is the adding of holes to the rudder where it does not affect the steering, yet make the rudder easy to turn. This innovation finally enabled European torpedo boats to use their rudders while traveling at high speed (about 30 knots).Junks employed stern-mounted rudders centuries before their adoption in the West for the simple reason that Western hull forms, with their pointed sterns, obviated a centreline steering system until technical developments in Scandinavia created the first, iron mounted, pintle and gudgeon ‘barn door’ western examples in the early 12th century CE. A second reason for this slow development was that the side rudders in use were, contrary to a lot of very ill-informed opinion, extremely efficient. Thus the junk rudder’s origin, form and construction was completely different in that it was the development of a centrally mounted stern steering oar, examples of which can also be seen in Middle Kingdom (c.2050-1800 BCE) Egyptian river vessels. It was an innovation which permitted the steering of large ships and due to its design allowed height adjustment according to the depth of the water and to avoid serious damage should the junk ground. A sizable junk can have a rudder that needed up to twenty members of the crew to control in strong weather. In addition to using the sail plan to balance the junk and take the strain off the hard to operate and mechanically weakly attached rudder, some junks were also equipped with leeboards or dagger boards. The world’s oldest known depiction of a stern-mounted rudder can be seen on a pottery model of a junk dating from before the 1st century AD,though some scholars think this may be a steering oar – a possible interpretation given that the model is of a river boat that was probably towed or poled. From sometime in the 13th to 15th centuries, many junks began incorporating "fenestrated" rudders (rudders with large diamond-shaped holes in them), probably adopted to lessen the force needed to direct the steering of the rudder. The rudder is reported to be the strongest part of the junk. In the Tiangong Kaiwu "Exploitation of the Works of Nature" (1637), Song Yingxing wrote, "The rudder-post is made of elm, or else of langmu or of zhumu." The Ming author also applauds the strength of the langmu wood as "if one could use a single silk thread to hoist a thousand jun or sustain the weight of a mountain landslide."
Generally, a rudder is "part of the steering apparatus of a boat or ship that is fastened outside the hull", that is denoting all different types of oars, paddles, and rudders. More specifically, the steering gear of ancient vessels can be classified into side-rudders and stern-mounted rudders, depending on their location on the ship. A third term, steering oar, can denote both types. In a Mediterranean context, side-rudders are more specifically called quarter-rudders as the later term designates more exactly the place where the rudder was mounted. Stern-mounted rudders are uniformly suspended at the back of the ship in a central position.
Although Lawrence Mott in his comprehensive treatment of the history of the rudder,Timothy Runyan,the Encyclopædia Britannica, and The Concise Oxford Dictionary of English Etymology classify a steering oar as a rudder, Joseph Needham, Lefèbre des Noëttes, K.S. Tom, Chung Chee Kit, S.A.M. Adshead, John K. Fairbank, Merle Goldman, Frank Ross, and Leo Block state that the steering oar used in ancient Egypt and Rome was not a true rudder and define stern-mounted rudder used in China as the true rudder;the steering oar has the capacity to interfere with handling of the sails (limiting any potential for long ocean-going voyages) while it was fit more for small vessels on narrow, rapid-water transport; the rudder did not disturb the handling of the sails, took less energy to operate by its helmsman, was better fit for larger vessels on ocean-going travel, and first appeared in ancient China during the 1st century AD.In regards to the ancient Phoenician (1550–300 BC) use of the steering oar without a rudder in the Mediterranean, Leo Block (2003) writes: A single sail tends to turn a vessel in an upwind or downwind direction, and rudder action is required to steer a straight course. A steering oar was used at this time because the rudder had not yet been invented. With a single sail, a frequent movement of the steering oar was required to steer a straight course; this slowed down the vessel because a steering oar (or rudder) course correction acts like a brake. The second sail, located forward, could be trimmed to offset the turning tendency of the main sail and minimize the need for course corrections by the steering oar, which would have substantially improved sail performance.
The steering oar or steering board is an oversized oar or board to control the direction of a ship or other watercraft prior to the invention of the rudder. It is normally attached to the starboard side in larger vessels, though in smaller ones it is rarely, if ever, attached. Stern-mounted steering oar of an Egyptian riverboat depicted in the Tomb of Menna (c. 1422-1411 BC) Rowing oars set aside for steering appeared on large Egyptian vessels long before the time of Menes (3100 BC). In the Old Kingdom (2686 BC-2134 BC) as much as five steering oars are found on each side of passenger boats. The tiller, at first a small pin run through the stock of the steering oar, can be traced to the fifth dynasty (2504–2347 BC).Both the tiller and the introduction of an upright steering post abaft reduced the usual number of necessary steering oars to one each side. Apart from side-rudders, single rudders put on the stern can be found in a number of tomb models of the time, particularly during the Middle Kingdom when tomb reliefs suggests them commonly employed in Nile navigation. The first literary reference appears in the works of the Greek historian Herodot (484-424 BC), who had spent several months in Egypt: "They make one rudder, and this is thrust through the keel", probably meaning the crotch at the end of the keel (see right pic "Tomb of Menna"). In Iran, oars mounted on the side of ships for steering are documented from the 3rd millennium BCE in artwork, wooden models, and even remnants of actual boats. Steering oar of a Roman boat, 1st century AD (RG-Museum, Cologne). Roman navigation used sexillie quarter steering oars which went in the Mediterranean through a long period of constant refinement and improvement, so that by Roman times ancient vessels reached extraordinary sizes.The strength of the steering oar lay in its combination of effectiveness, adaptability and simpleness. Roman quarter steering oar mounting systems survived mostly intact through the medieval period. By the first half of the 1st century AD, steering gear mounted on the stern were also quite common in Roman river and harbour craft as proved from reliefs and archaeological finds (Zwammderdam, Woerden 7). A tomb plaque of Hadrianic age shows a harbour tug boat in Ostia with a long stern-mounted oar for better leverage. Interestingly, the boat already featured a spritsail, adding to the mobility of the harbour vessel. Further attested Roman uses of stern-mounted steering oars includes barges under tow, transport ships for wine casks, and diverse other ship types. Also, the well-known Zwammerdam find, a large river barge at the mouth of the Rhine, featured a large steering gear mounted on the stern. According to new research, the advanced Nemi ships, the palace barges of emperor Caligula (37-41 AD), may have featured 14 m long rudders.
An Eastern Han (25–220 AD) Chinese pottery boat fit for riverine and maritime sea travel, with an anchor at the bow, a steering rudder at the stern, roofed compartments with windows and doors, and miniature sailors. An early Song Dynasty (960–1279) painting on silk of two Chinese cargo ships accompanied by a smaller boat, by Guo Zhongshu (c. 910–977 AD); notice the large sternpost-mounted rudder on the ship shown in the foreground The world’s oldest known depiction of a sternpost-mounted rudder can be seen on a pottery model of a Chinese junk dating from the 1st century AD during the Han Dynasty, predating their appearance in the West by a thousand years. In China, miniature models of ships that feature steering oars have been dated to the Zhou Dynasty (c. 1050–256 BC). Sternpost-mounted rudders started to appear on Chinese ship models starting in the 1st century AD. However, the Chinese continued to use the steering oar long after they invented the rudder, since the steering oar still had limited practical use for inland rapid-river travel. One of oldest known depiction of a stern-mounted rudder in China can be seen on a 2-foot-long tomb pottery model of a junk dating from the 1st century AD, during the Han Dynasty (202 BC-220 AD). It was discovered in Guangzhou in an archaeological excavation carried out by the Guangdong Provincial Museum and Academia Sinica of Taiwan in 1958. Within decades, several other Han Dynasty ship models featuring rudders were found in archaeological excavations. The first solid written reference to the use of a rudder without a steering oar dates to the 5th century.
Chinese rudders were not supported by pintle-and-gudgeon as in the Western tradition; rather, they were attached to the hull by means of wooden jaws or sockets, while typically larger ones were suspended from above by a rope tackle system so that they could be raised or lowered into the water. Also, many junks incorporated "fenestrated rudders" (rudders with holes in them, supposedly allowing for better control). Detailed descriptions of Chinese junks during the Middle Ages are known from various travellers to China, such as Ibn Battuta of Tangier, Morocco and Marco Polo of Venice, Italy. The later Chinese encyclopedist Song Yingxing (1587–1666) and the 17th-century European traveler Louis Lecomte wrote of the junk design and its use of the rudder with enthusiasm and admiration. Pottery boat from Eastern Han Dynasty showing rudder Paul Johnstone and Sean McGrail state that the Chinese invented the "median, vertical and axial" sternpost-mounted rudder, and that such a kind of rudder preceded the pintle-and-gudgeon rudder found in the West by roughly a millennium. However, Lawrence Mott points out that the method of mounting steering gear from the stern was well known in Mediterranean navigation by the time the practice appeared in Chinese ships.
Arab ships also used a sternpost-mounted rudder.On their ships "the rudder is controlled by two lines, each attached to a crosspiece mounted on the rudder head perpendicular to the plane of the rudder blade."The earliest evidence comes from the Ahsan al-Taqasim fi Marifat al-Aqalim (‘The Best Divisions for the Classification of Regions’) written by al-Muqaddasi in 985: The captain from the crow’s nest carefully observes the sea. When a rock is espied, he shouts: "Starboard!" or ‘Port!" Two youths, posted there, repeat the cry. The helmsman, with two ropes in his hand, when he hears the calls tugs one or the other to the right or left. If great care is not taken, the ship strikes the rocks and is wrecked.
Pintle-and-gudgeon rudder of the Hanseatic league flagship Adler von Lübeck (1567–1581), the largest ship in the world at its time. Oars mounted on the side of ships evolved into quarter rudders, which were used from antiquity until the end of the Middle Ages in Europe. As the size of ships and the height of the freeboards increased, quarter-rudders became unwieldy and were replaced by the more sturdy stern-mounted rudders with pintle and gudgeon attachment. While stern-mounted rudders were found in Europe on a wide range of vessels since Roman times, including light war galleys in Mediterranean, the oldest known depiction of a pintle-and-gudgeon rudder can be found on church carvings of Zedelgem and Winchester dating to around 1180. A ship’s rudder carved in oak, 15th century, Bere Ferrers church, Devon. Heraldic badge of Cheyne and Willoughby families
Historically, the radical concept of the medieval pintle-and-gudgeon rudder did not come as a single invention into being. It presented rather a combination of ideas which each had been long around before: rudders mounted on the stern, iron hinges and the straight sternpost of northern European ships. While earlier rudders were mounted on the stern by the way of rudderposts or tackles, the iron hinges allowed for the first time to attach the rudder to the entire length of the sternpost in a really permanent fashion. However, its full potential could only to be realized after the introduction of the vertical sternpost and the full-rigged ship in the 14th century. From the age of discovery onwards, European ships with pintle-and-gudgeon rudders sailed successfully on all seven seas. Many historians’ consensus considered the technology of stern-mounted rudder in Europe and Islam World, which was introduced by travelers in the Middle Ages, was transferred from China. However, Lawrence Mott in his master thesis stated that the method of attachment for rudders in the Chinese and European worlds differed from each other, leading him to doubt the spread of the Chinese system of attachment
Boat rudders may be either outboard or inboard. Outboard rudders are hung on the stern or transom. Inboard rudders are hung from a keel or skeg and are thus fully submerged beneath the hull, connected to the steering mechanism by a rudder post which comes up through the hull to deck level, often into a cockpit. Inboard keel hung rudders (which are a continuation of the aft trailing edge of the full keel) are traditionally deemed the most damage resistant rudders for off shore sailing. Better performance with faster handling characteristics can be provided by skeg hung rudders on boats with smaller fin keels. Rudder post and mast placement defines the difference between a ketch and a yawl, as these two-masted vessels are similar. Yawls are defined as having the mizzen mast abaft (i.e. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post. Small boat rudders that can be steered more or less perpendicular to the hull’s longitudinal axis make effective brakes when pushed "hard over." However, terms such as "hard over," "hard to starboard," etc. signify a maximum-rate turn for larger vessels. Transom hung rudders or far aft mounted fin rudders generate greater moment and faster turning than more forward mounted keel hung rudders.
There is also the barrel type rudder where the ships screw is enclosed and can be swiveled to steer the vessel. Designers claim that this type of rudder on a smaller vessel will answer the helm faster.
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