The Mechanism of Extension in the Legs of Spiders

Ellis, C. H.

doi:10.2307/1537950

Cited by 73 publications

(29 citation statements)

References 7 publications

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“…Thereupon Ellis [27] disproved previous assumptions [25] that the extension is solely generated by the membrane's elasticity and provided the experimental evidence for a relationship between the internal fluidic pressure in the spider leg and the joint extension. Parry and Brown [28] then experimentally determined values and roughly calculated relations for pressure, torque, and fluidic volumes.…”

Section: Hydraulic Leg Extensionmentioning

confidence: 87%

Biomimetic Spider Leg Joints: A Review from Biomechanical Research to Compliant Robotic Actuators

et al. 2016

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Due to their inherent compliance, soft actuated joints are becoming increasingly important for robotic applications, especially when human-robot-interactions are expected. Several of these flexible actuators are inspired by biological models. One perfect showpiece for biomimetic robots is the spider leg, because it combines lightweight design and graceful movements with powerful and dynamic actuation. Building on this motivation, the review article focuses on compliant robotic joints inspired by the function principle of the spider leg. The mechanism is introduced by an overview of existing biological and biomechanical research. Thereupon a classification of robots that are bio-inspired by spider joints is presented. Based on this, the biomimetic robot applications referring to the spider principle are identified and discussed.

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Section: Hydraulic Leg Extensionmentioning

confidence: 87%

Biomimetic Spider Leg Joints: A Review from Biomechanical Research to Compliant Robotic Actuators

et al. 2016

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“…Consequently, previous research has found no extensor muscles (e.g. Ellis, 1944;Parry and Brown, 1959a;Whitehead and Rempel, 1959;Ruhland and Rathmayer, 1978). Active muscles traversing these joints induce flexion.…”

Section: Introductionmentioning

confidence: 93%

Hydraulic leg extension is not necessarily the main drive in large spiders

Weihmann

Günther

Blickhan

2012

Journal of Experimental Biology

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SUMMARYUnlike most other arthropods, spiders have no extensor muscles in major leg joints. Therefore, hydraulic pressure generated in the prosoma provides leg extension. For decades, this mechanism was held responsible for the generation of the majority of the ground reaction forces, particularly in the hind legs. During propulsion, the front leg pairs must shorten whereas the hind legs have to be extended. Assuming that hind legs are essentially driven by hydraulics, their force vectors must pass the leg joints ventrally. However, at least in accelerated escape manoeuvres, we show here for the large cursorial spider species Ancylometes concolor that these force vectors, when projected into the leg plane, pass all leg joints dorsally. This indicates a reduced impact of the hydraulic mechanism on the generation of ground reaction forces. Although hydraulic leg extension still modulates their direction, the observed steep force vectors at the hind legs indicate a strong activity of flexors in the proximal joint complex that push the legs against the substrate. Consequently, the muscular mechanisms are dominant at least in the hind legs of large spiders.

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“…Instead of using muscles, spiders extend the proximal femur-patella and the distal tibia-metatarsal joints of their legs hydraulically (Ellis, 1944;Parry and Brown, 1959;Wilson, 1970;Kropf, 2013;Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature on leg kinematics in sprinting tarantulas (Aphonopelma hentzi): high speed may limit hydraulic joint actuation

Booster

Adolph

et al. 2015

Journal of Experimental Biology

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Tarantulas extend the femur-patella ( proximal) and tibia-metatarsal (distal) joints of their legs hydraulically. Because these two hydraulically actuated joints are positioned in series, hemolymph flow within each leg is expected to mechanically couple the movement of the joints. In the current study, we tested two hypotheses: (1) at lower temperatures, movement of the two in-series hydraulic joints within a leg will be less coupled because of increased hemolymph viscosity slowing hemolymph flow; and (2) at higher temperatures, movement of the two in-series hydraulic joints will be less coupled because the higher stride frequencies limit the time available for hemolymph flow. We elicited maximal running speeds at four ecologically relevant temperatures (15, 24, 31 and 40°C) in Texas Brown tarantulas (Aphonopelma hentzi). The spiders increased sprint speed 2.5-fold over the temperature range by changing their stride frequency but not stride length. The coefficient of determination for linear regression (R 2 ) of the proximal and distal joint angles was used as the measure of the degree of coupling between the two joints. This coupling coefficient between the proximal and distal joint angles, for both forelegs and hindlegs, was significantly lowest at the highest temperature at which the animals ran the fastest with the highest stride frequencies. The coordination of multiple, in-series hydraulically actuated joints may be limited by operating speed.

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The Mechanism of Extension in the Legs of Spiders

Cited by 73 publications

References 7 publications

Biomimetic Spider Leg Joints: A Review from Biomechanical Research to Compliant Robotic Actuators

Biomimetic Spider Leg Joints: A Review from Biomechanical Research to Compliant Robotic Actuators

Hydraulic leg extension is not necessarily the main drive in large spiders

Effect of temperature on leg kinematics in sprinting tarantulas (Aphonopelma hentzi): high speed may limit hydraulic joint actuation

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