Intelligent Approaches in Locomotion - A Review <s> Introduction <s> This paper presents how neural swimming controllers for a simulated lamprey can be developed using evolutionary algorithms. A genetic algorithm is used for evolving the architecture of a connectionist model which determines the muscular activity of a simulated body in interaction with water. This work is inspired by the biological model developed by Ekeberg which repro duces the central pattern generator observed in the real lamprey (Ekeberg, 1993). In evolving artificial controllers, we demonstrate that a genetic algorithm can be an interesting design tech nique for neural controllers and that there exist alternative solutions to the biological connectiv ity. A variety of neural controllers are evolved which can produce the pattern of oscillations necessary for swimming. These patterns can be modulated through the external excitation ap plied to the network in order to vary the speed and the direction of swimming. The best evolved controllers cover larger ranges of frequencies, phase lags and speeds of s... <s> BIB001 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> We describe an evolutionary approach to the control problem of bipedal walking. Using a full rigid-body simulation of a biped, it was possible to evolve recurrent neural networks that controlled stable straight-line walking on a planar surface. No proprioceptive information was necessary in order to achieve this task. Furthermore, simple sensory input to locate a sound source was integrated to achieve directional walking. To our knowledge, this is the first work that demonstrates the application of evolutionary optimization to 3D physically simulated biped locomotion. <s> BIB002 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> Abstract This paper presents humanoid robotics platform that consists of a humanoid robot and an open architecture software platform developed in METI’s Humanoid Robotics Project (HRP). The final version of the robot, called HRP-2, has 1540 mm height, 58 kg weight and 30 degrees of the freedom. The software platform includes a dynamics simulator and motion controllers of the robot for biped locomotion, falling and getting up motions. The platform has been used to develop various applications and is expected to initiate more humanoid robotics research. <s> BIB003 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> Human motion capture embeds rich detail and style which is difficult to generate with competing animation synthesis technologies. However, such recorded data requires principled means for creating responses in unpredicted situations, for example reactions immediately following impact. This paper introduces a novel technique for incorporating unexpected impacts into a motion capture-driven animation system through the combination of a physical simulation which responds to contact forces and a specialized search routine which determines the best plausible re-entry into motion library playback following the impact. Using an actuated dynamic model, our system generates a physics-based response while connecting motion capture segments. Our method allows characters to respond to unexpected changes in the environment based on the specific dynamic effects of a given contact while also taking advantage of the realistic movement made available through motion capture. We show the results of our system under various conditions and with varying responses using martial arts motion capture as a testbed. <s> BIB004 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> This paper presents the virtual height inverted pendulum mode (VHIPM), which is a simple and effective trajectory generation method for the stable walking of biped robots. VHIPM, which is based on the inverted pendulum mode (IPM), can significantly reduce the zero moment point (ZMP) error by adjusting the height in the inverted pendulum. We show the relationship between VHIPM and other popular trajectory generation methods, and compare the ZMP errors in walking when trajectories are generated by various methods including VHIPM. We also investigate the sensitivity of the ZMP error in VHIPM to the step length, walking period and mass distribution of a robot. The simulation results show that VHIPM significantly reduces the ZMP errors compared to other methods under various circumstances. <s> BIB005 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> Biped robot with heterogeneous legs (BRHL) is a novel robot model, which consists of an artificial leg and an intelligent bionic leg. The artificial leg is used to simulate the amputeepsilas healthy leg and the bionic leg works as the intelligent artificial limb. To describe the present gait of the healthy leg and make intelligent bionic leg follow the walking of artificial leg in all phases is the target of BRHLpsilas research. So gait planning of artificial leg is the emphasis of BRHLpsilas research. This paper uses the model of central pattern generator (CPG) in the research of artificial legpsilas gait planning from the point of biology. To obtain natural and robust walking pattern, genetic algorithm is used to optimize parameters of the CPG network model and the fitness function is formulated based on zero moment point (ZMP). Simulation results testify the feasibility of this method. <s> BIB006 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> Biological systems seem to have a simpler but more robust locomotion strategy than that of the existing biped walking controllers for humanoid robots. We show that a humanoid robot can step and walk using simple sinusoidal desired joint trajectories with their phase adjusted by a coupled oscillator model. We use the center-of-pressure location and velocity to detect the phase of the lateral robot dynamics. This phase information is used to modulate the desired joint trajectories. We do not explicitly use dynamical parameters of the humanoid robot. We hypothesize that a similar mechanism may exist in biological systems. We applied the proposed biologically inspired control strategy to our newly developed human-sized humanoid robot computational brain (CB) and a small size humanoid robot, enabling them to generate successful stepping and walking patterns. <s> BIB007 </s> Intelligent Approaches in Locomotion - A Review <s> Introduction <s> The objective of the work presented here is to develop a low cost active above knee prosthetic device exploiting bipedal robotics technology which will work utilizing the available biological motor control circuit properly integrated with a Central Pattern Generator (CPG) based control scheme. The approach is completely different from the existing Active Prosthetic devices, designed primarily as standalone systems utilizing multiple sensors and embedded rigid control schemes. In this research, first we designed a fuzzy logic based methodology for offering suitable gait pattern for an amputee, followed by formulating a suitable algorithm for designing a CPG, based on Rayleigh's oscillator. An indigenous probe, Humanoid Gait Oscillator Detector (HGOD) has been designed for capturing gait patterns from various individuals of different height, weight and age. These data are used to design a Fuzzy inference system which generates most suitable gait pattern for an amputee. The output of the Fuzzy inference system is used for designing a CPG best suitable for the amputee. We then developed a CPG based control scheme for calculating the damping profile in real time for maneuvering a prosthetic device called AMAL (Adaptive Modular Active Leg). Also a number of simulation results are presented which show the stable behavior of knee and hip angles and determine the stable limit cycles of the network. <s> BIB008
This paper presents a review of published locomotion control methods. The objective of the paper is to present a comparative overview of the field, so that the reader may make informed choices in investigating techniques suitable for their application. To accomplish this, each major technique identified in the literature is summarised, assessed and compared in the final discussion. Over 140 papers were reviewed, with comparison of techniques acheived by categorising them, establishing key properties and comparing in terms of scope of application, ease of parameterisation, and any desirable or undesirable characteristics. As many of the reviewed techniques require extensive parameter specification, this review also outlines key techniques of learning and optimisation as applied in the field. The rest of the paper is organised as follows. In section 2, analytical approaches are presented and subdivided into such that control bipeds (a major topic with demanding stability issues), and such that control other types of systems. In section 3, approaches inspired by biological solutions are presented and central pattern generators (CPGs) , that create patterns based on oscillator primitives, are introduced. They allow more generalized ways of parameterisation of the movement patterns than the analytical approaches. Neural networks based solutions are discussed in section 4. They offer an even more generalized approach than the CPGs and give more options for learning rules and optimisation. In section 5, Hidden Markov Model (HMM) techniques are presented and their use for skill observation, classification and imitation is analysed. Transition table and fuzzy logic approaches are discussed as generalized state based methods in section 6. Finally, a comparison and summary of the presented methods are given in section 7. Numerous parameterisation techniques have been used in the literature, from simple manual specification, through to optimisation. A summary is given in each section, and an overall grouping of references by technique is given in Table 1 . Locomotion is the process of moving an organism or synthetic creature around an environment. Artificially producing locomotion is required in a range of disciplines including robot control BIB005 - BIB002 , artificial limb control BIB006 , BIB008 , computer animation BIB004 , and biological studies BIB001 . Locomotion may be needed for simulated models BIB005 or real world systems such as robots BIB003 . Generation of the movement patterns in locomotion is often a non-trivial task, for which a range of analytical and intelligent solutions have been developed BIB005 , BIB007 , BIB001 . The complexity of the problems ranges from producing straight line movement in a flat environment, to steerable Table 2 : Reviewed references organised by control method and target system. For each target system, the references are grouped into those that examine only simulated systems or theoretical work (Sim) , and those that have tested the methods in real-world hardware (Hard).