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4: Hexapod of McGhee In 1977, McGhee and his group at Ohio State University developed the OSU-Hexapod, a six-legged insect-like machine (Fig. 2.4). This vehicle was equipped with force sensors, gyroscopes, proximity sensors and a camera system and was fully controlled by a PDP 11/70. Active force sensing has been used in the control system. The parameters of the machine are as follows: body length 1,3 m body width 1,4 m, weight about 100 kg, velocity about 0,1 m/s (McGhee, 1977; McGhee & Iswandhi, 1979; Klein & Briggs, 1980). It has been used for a variety of experiments, like walking with different gaits on a flat surface, climbing up shallow stairs and walking over obstacles (Ozguner et al., 1984). These results in building optimal leg construction and the developed theory of walking layed the basis for the biggest walking machine project at that time. In 1982, Waldron and his group at Ohio State University started with realization of the Adaptive Suspension Vehicle (ASV) (Fig. 2.5). The aim of the project was an easily steerable, big and efficient machine that could be used at natural ground conditions (Song & Waldron, 1989).
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The control system algorithms and their technical realization for the robots "Masha" and "Katharina" are described in (Schmucker et al., 1996; Schmucker, 2002). Each leg of "Katharina" has its own controller based on a microcontroller INTEL 87C196KR which only controls the respective leg. The controller includes the CPU, FLASH-memory and RAM, a PWM...
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Interconnected devices are becoming attractive solutions to integrate physical parameters and make them more accessible for further analysis. The exploding number of sensors are demanding huge bandwidth and computational capabilities in the cloud. Additionally, continuous transmission of information to the remote server would hamper privacy. Deep N...
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... Providing force information to the robots increases their operational ability. Contact force estimation enables them to obtain new mechanical characteristics and enables the ability of simplifying many of the control algorithms [2]. Many approaches have been developed to give this capability to robots. ...
In this paper, we present algorithms to estimate contact locations, external forces and joint torques using skin, i.e. distributed tactile sensors, kinematic sensors and a single IMU without the need for force-torque sensors. Distributed tactile sensors are an array of discrete tactile sensors (taxels) with gaps between them. To cope with the gaps, we use interpolation techniques to improve accuracy of the measurements in the skin. Then, we estimate the external force. Finally, we use this information combined with the contact location obtained from the skin to estimate the joint torques. Validation was performed using the iCub humanoid robot. Results show a performance comparable to the joint torque estimation using expensive force-torque sensors. Since the skin is less expensive and does not required modifying the internal structure of the robot, using the skin is an interesting solution.
... The first hexapods can be identified as robots based on a rigidly predetermined motion so that an adaptation to the ground was not possible. Early researches in the 1950s were focused on assigning the motion control completely by a human operator manually [11]. One of the first successful hexapod robot was constructed at University of Rome in 1972 (Figure 1a) as a computer-controlled walking machine with electric drives [12]. ...
Hexapod walking robots have attracted considerable attention for several decades. Many studies have been carried out in research centers, universities and industries. However, only in the recent past have efficient walking machines been conceived, designed and built with performances that can be suitable for practical applications. This paper gives an overview of the state of the art on hexapod walking robots by referring both to the early design solutions and the most recent achievements. Careful attention is given to the main design issues and constraints that influence the technical feasibility and operation performance. A design procedure is outlined in order to systematically design a hexapod walking robot. In particular, the proposed design procedure takes into account the main features, such as mechanical structure and leg configuration, actuating and driving systems, payload, motion conditions, and walking gait. A case study is described in order to show the effectiveness and feasibility of the proposed design procedure.
... Similar synergies may underlie muscle activation patterns in walking (Chvatal et al. 2011;Neptune et al. 2009). The regulation of forces has also been successfully adopted in simulations of walking and in the control of legged robots (Ekeberg and Pearson 2005;Schneider and Schmucker 2006). In control systems and models, forces are often defined as vectors within a reference frame (Raptis et al. 2010). ...
The regulation of forces is integral to motor control. However, it is unclear how information from sense organs that detect forces at individual muscles or joints is incorporated into a frame of reference for motor control. Campaniform sensilla are receptors that monitor forces by cuticular strains. We studied how loads and muscle forces are encoded by trochanteral campaniform sensilla in stick insects. Forces were applied to the middle leg to emulate loading and/or muscle contractions. Selective sensory ablations limited activities recorded in the main leg nerve to specific receptor groups. The trochanteral campaniform sensilla consist of four discrete groups. We found that the dorsal groups (Groups 3 and 4) encoded force increases and decreases in the plane of movement of the coxo-trochanteral joint. Group 3 receptors discharged to increases in dorsal loading and decreases in ventral load. Group 4 showed the reverse directional sensitivities. Vigorous, directional responses also occurred to contractions of the trochanteral depressor muscle and to forces applied at the muscle insertion. All sensory discharges encoded the amplitude and rate of loading or muscle force. Stimulation of the receptors produced reflex effects in the depressor motoneurons that could reverse in sign during active movements. These data, in conjunction with findings of previous studies, support a model in which the trochanteral receptors function as an array that can detect forces in all directions relative to the intrinsic plane of leg movement. The array could provide requisite information about forces and simplify the control and adaptation of posture and walking.
Natural disasters are becoming more prevalent attributed to climate change in this rapidly developing era. With the dramatic increase in natural disasters brought on by human innovation, there will be a correlated increase in human society’s casualties. With the rapid development of technology, we believe that constructing an autonomous or a software-controlled robotic spider where its functionalities can include avoiding obstacles and navigating in rough terrain can solve this issue. Hexapod spider robots can also benefit from vital movement in their natural surroundings and low impact on the terrain. A mechanical spider can navigate and verve places where humans don’t have the ability to, essentially acting as a rescue robot. For example, suppose there is an earthquake and a tiny space where a human cannot fit. In that case, the robot will have the ability to accomplish that task—any natural disaster such as a hurricane, exploring war zones, and even volcanic eruption. Most of the Hexapod-legged robots have been used to explore hostile and remote environments such as seabed, nuclear power stations, and even different planets. This paper’s primary goal is to implement a six-legged spider robot that can move in a fluid movement that is balanced and can navigate effectively.
This review article aims to address common research questions in hexapod robotics. How can we build intelligent autonomous hexapod robots that can exploit their biomechanics, morphology, and computational systems, to achieve autonomy, adaptability, and energy efficiency comparable to small living creatures, such as insects? Are insects good models for building such intelligent hexapod robots because they are the only animals with six legs? This review article is divided into three main sections to address these questions, as well as to assist roboticists in identifying relevant and future directions in the field of hexapod robotics over the next decade. After an introduction in section (1), the sections will respectively cover the following three key areas: (2) biomechanics focused on the design of smart legs; (3) locomotion control; and (4) high-level cognition control. These interconnected and interdependent areas are all crucial to improving the level of performance of hexapod robotics in terms of energy efficiency, terrain adaptability, autonomy, and operational range. We will also discuss how the next generation of bioroboticists will be able to transfer knowledge from biology to robotics and vice versa.
Hexapod walking robots have been widely addressed in the literature with a very large number of design and engineering solutions. However, specific design approaches and solutions are needed to cope with specific novel applications. This paper aims to address the design of a hexapod walking robot having exploration, architectonic survey, and maintenance of cultural heritage goods as its main application tasks. This specific case of study is addressed by carrying out a detailed design, which led to the construction of a novel hexapod walking robot, named Cassino Hexapod III. The proposed robot is composed of hybrid legs of a modular anthropomorphic architecture with omni-wheels as feet at its extremity. The proposed design and engineering solutions can overcome the limits of other existing prototypes and to fulfil the specific application requirements and constraints with a cost-effective and user-friendly solution. The proposed novel solutions have also originated an Italian patent No. 102014902238772.
In this contribution, several strategies of force control have been proposed to be implemented and evaluated in ROBOCLIMBER, a quadruped robot of large dimensions. A first group of strategies proposed in this paper is based on impedance control, which is intended to adapt the foot-ground contact forces according to the experimentally specified damping ratio and the undamped natural frequency. A second control strategy of interest for many practical cases is called the parallel force/position control, which has one inner loop position control and two external control loops, one of force and another of position. A third group of control strategies is the posture stabilization for ROBOCLIMBER using the feedback of the ZMP calculation and the position of its legs. Finally, a control strategy for the control of a quasi-static gait using ZMP feedback is proposed and tested by simulation.
Path planning, gait planning and trajectory planning are assuming an increasing significance for Hexapod Walking robots and more generally, in legged robotics. Indeed, the trend for walking robots is to improve the speed, the stability, the navigation autonomy and the energy efficiency. In this Chapter it will be addressed the problem of Hexapod Walking Robots (HWR) locomotion. An overview of the State of the Art is carried out with references to the numerous contributions to this field. It will be provided a background on the topics of path planning, gait and trajec-tory planning for HWR locomotion. Special attention will be given to the hexapod gaits, starting from their classification together with a detailed description of most common ones. A case of study is described as referring to previous experiences at LARM in Cassino. Examples of a path planning, gait and trajectory planning are provided through kinematic and dynamic features of Cassino Hexapod leg operation.
