and enjoyment of walking. Examples of types of investment include pedestrian malls, and foreshoreways such as oceanways and also river walks. The first purpose-built pedestrian street in Europe is the Lijnbaan in Rotterdam, opened in 1953. The first pedestrianised shopping centre in the United Kingdom was in Stevenage in 1959. A large number of European towns and cities have made part of their centres car-free since the early 1960s. These are often accompanied by car parks on the edge of the pedestrianised zone, and, in the larger cases, park and ride schemes. Central Copenhagen is one of the largest and oldest: It was converted from car traffic into pedestrian zone in 1962. In robotics Generally, the first successful walking robots had six legs. As microprocessor technology advanced, the number of legs could be reduced and there are now robots that can walk on two legs. One, for example, is ASIMO. Although there has been significant advances, robots still do not walk nearly as well as human beings as they often need to keep their knees bent permanently in order to improve stability. In 2009, Japanese roboticist Tomotaka Takahashi developed a robot that can jump three inches off the ground. The robot, named Ropid, is capable of getting up, walking, running, and jumping. Many other robots have also been able to walk over the years like a bipedal walking robot. Mathematical models Multiple mathematical models have been proposed to reproduce the kinematics observed in walking. These may be broadly broken down into four categories: rule-based models based on mechanical considerations and past literature, weakly coupled phase oscillators models, control-based models which guide simulations to maximize some property of locomotion, and phenomenological models which fit equations directly to the kinematics. Rule-based models The rule-based models integrate the past literature on motor control to generate a few simple rules which are presumed to be responsible for walking (e.g. “loading of the left leg triggers unloading of right leg”). Such models are generally most strictly based on the past literature and when they are based on a few rules can be easy to interpret. However, the influence of each rule can be hard to interpret when these models become more complex. Furthermore, the tuning of parameters is often done in an ad hoc way, revealing little intuition about why the system may be organized in this way. Finally, such models are typically based fully