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The wrist is an articular group that joins the hand to the forearm. It gathers the different articular spaces between the forearm bones (radius and ulna), the carpal bones, and the palm bones (the metacarpals). In the sagittal plane, the wrist can move in flexion, carrying the palm forward and upward, and extension, carrying the palm backward and downward. In the volar plane, the motions allowed are the radial inclination, or abduction, carrying the axis of the hand outward, and the ulnar inclination, or adduction, carrying the axis of the hand inward. The elbow is a complex structure that allows flexion of the forearm on the arm and also pronation and supination of the forearm in order to provide the human ability to interact both with himself and with the environment. Combination of mobility and stability is the main challenge that is met by this very congruent set of joints, which make possible subtle and accurate motions as well as weight-bearing. Flexion and extension of the elbow are provided by the ulnohumeral and radiohumeral joints, whereas pronation and supination motions involve the radiohumeral joint and the radioulnar joint., SCOPUS: ch.b, info:eu-repo/semantics/published

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

A structure of present gait analysis laboratory has several cameras located around a walkway, which are linked to a computer. The patient has markers placed at various reference points of the body, or groups of markers covered to half of the body segments. The subject walks down the pathway or the treadmill and the computer with cameras measures the trajectory of each marker located on body in three dimensions. A model is preferred to evaluate the movement of the subject joints. This gives a complete overview of the orientation of each joint. The instruments and tools used in present gait analysis laboratory are very expensive, so it is not possible to implement it in every clinic of India. In proposed system walking video is used for gait analysis. A Video is captured from the sagittal plane as well as frontal plane; a pathway will be prepared for volunteer walking. Volunteer walking video will be captured by the frontal and sagittal plane camera. The captured video is going to be processed by MATLAB software for feature extraction like joint angles. A program is going to developed in MATLAB to perform operations like video to frame conversion, selection of gait phase frames, location extraction of markers, forming stick figure and angle measurement

This paper presents a real-time gait analyzer used to record the gait pattern of a subject which can beprimary input to lower extremity exoskeletons. Studies have been carried out on walking behaviour ofsubjects indicating that lower extremity exoskeletons can take inputs as hip and knee joint movement anglesin sagittal plane. Wearable gait motion analyzer can be used to operate lower extremity exoskeletons in twodifferent modes: real-time gait and pre-defined gait. For pre-defined gait mode, wearable gait motionanalyzer provides wearer specific gait pattern of hip and knee joint angles in sagittal plane. A comparisonstudy on gait data obtained from gait lab and wearable gait motion analyser was carried out and showed 98%correlation match. Gyroscopes of IMU are also used to measure angular velocity of hip and knee joints toestimate specifications of exoskeleton actuators.

3D non-contact surface scanners capture highly accurate, calibrated images of surface topography for 3D structures. This study sought to establish the efficacy and accuracy of using 3D surface scanning (3DSS) to characterise thoracolumbar spinal curvature and sagittal plane profile. A comparison of the observed trends for change in spinal alignment measured from 3DSS and MRI, suggested the surface markers provide a useful method for measuring internal changes in sagittal curvature. Future work will include a larger cohort and coronal plane measurements.

This research examined the sample of 79 pre-school boys 6 and 7 years old, of which 40 participants in experimental group and 39 in control group, the present condition of the postural status and body composition, and their relationship after implemented six months treatment of fitness exercising in the experimental group of participants in order to examine the effect of the same. The experimental group, in addition to regular programme activities in the children school of sport (three times per week) had two more classes per week in 48 additional training classes 6 months in duration in sport fitness clubs. To estimate the body components the following variables have been applied obtained by the Bio-electric impedance In Body 230: muscle mass, percentage of muscle mass, body fat mass, percentage of the body fat mass, fat free mass, percentage of fat free mass. For the estimation of the postural status characteristics in the sagittal and frontal planes and foot vault decrease the following variables are used by the application of the device 3D analysis of the backbone Spinal Mouse and Foot Disc: degree of curvature in thoracic spine, degree of curvature in lumbar spine, spine inclination, and degree of the foot vault decrease. The findings obtained by the double ANOVA are small to moderate and they show that the experimental group had significantly higher advancement than the control group. Regarding the individual findings of the eta coefficient in relation with each group separately between measurements it is visible that value of obtained effects differentiates between groups in favour to the experimental one. Results of this research should serve the function of the most informative indicators that will enrich technological process of managing, monitoring, control improving, and optimizing the programmed exercising in the given population. Permanent implementation of the proposed programme could contribute improvement of the final postural status in children and

The aim of this study was to evaluate the effect of an industrial exoskeleton on muscle activity, perceived musculoskeletal effort, measured and perceived contact pressure at the trunk, thighs and shoulders, and subjective usability for simple sagittal plane lifting and lowering conditions. Twelve male participants lifted and lowered a box of 7.5 kg and 15 kg, respectively, from mid-shin height to waist height, five times, both with and without the exoskeleton. The device significantly reduced muscle activity of the Erector Spinae (12%-15%) and Biceps Femoris (5%). Ratings of perceived musculoskeletal effort in the trunk region were significantly less with the device (9.5%-11.4%). The measured contact pressure was highest on the trunk (91.7 kPa-93.8 kPa) and least on shoulders (47.6 kPa-51.7 kPa), whereas pressure was perceived highest on the thighs (35-44% of Max LPP). Six of the users rated the device usability as acceptable. The exoskeleton reduced musculoskeletal loading on the lower back and assisted with hip extensor torque during lifting and lowering. Contact pressures fell below the Pain Pressure Threshold. Perceived pressure was not exceptionally high, but sufficiently high to cause discomfort if used for long durations.

Previous adolescent idiopathic scoliosis (AIS) studies suggest anterior overgrowth of vertebral bodies (VB) contribute to scoliotic curve progression and reduced kyphosis. To understand how sagittal parameters change with scoliotic curve progression, this study used a sequential series of magnetic resonance images (MRI) for both AIS patients and non-scoliotic controls. VB wedge angles, intervertebral disc (IVD) wedge angles and kyphosis were compared at three time-points during adolescent growth to assess any changes in sagittal plane measures.

Association of low back pain and standing postural control (PC) deficits are reported inconsistently. Demands on PC adaptation strategies are increased by restraining the input of visual or somatosensory senses. The objectives of the current study are, to investigate whether PC adaptations of the spine, hip and the centre of pressure (COP) differ between patients reporting non-specific low back pain (NSLBP) and asymptomatic controls. The PC adaption strategies of the thoracic and lumbar spine, the hip and the COP were measured in fifty-seven NSLBP patients and 22 asymptomatic controls. We tested three "feet together" conditions with increasing demands on PC strategies, using inertial measurement units (IMUs) on the spine and a Wii balance board for centre of pressure (COP) parameters. The differences between NSLBP patients and controls were most apparent when the participants were blindfolded, but remaining on a firm surface. While NSLBP patients had larger thoracic and lumbar spine mean absolute deviations of position (MADpos) in the frontal plane, the same parameters decreased in control subjects (relative change (RC): 0.23, 95% confidence interval: 0.03 to 0.45 and 0.03 to 0.48). The Mean absolute deviation of velocity (MADvel) of the thoracic spine in the frontal plane showed a similar and significant effect (RC: 0.12 95% CI: 0.01 to 0.25). Gender, age and pain during the measurements affected some parameters significantly. PC adaptions differ between NSLBP patients and asymptomatic controls. The differences are most apparent for the thoracic and lumbar parameters of MADpos, in the frontal plane and while the visual condition was removed.

The goal of this study was to assess whether dancers of Spanish dance had better curvatures of the thoracic and lumbar spine than the rest of the population. The study assessed 34 students of Spanish dance from a professional dance conservatory, with an average age of 17.06 ± 2.86 years, and average practice time of 10.65 ± 3.41 years. The study measured the sagittal spinal curvatures of the dancers in a relaxed standing position. The measurements were performed using a uni-level inclinometer. The main findings revealed that the average thoracic kyphosis was 34.18 ± 5.10, and the average lumbar lordosis was 28.71 ± 4.91. The average values of the sagittal plane alignment of the thoracic and lumbar spine of the dancers in the standing position were normal, according to the scale proposed by Santoja (1993) and Contreras et al. (1981). There were no statistically significant differences; however, it was observed that the more advanced dance courses, the less thoracic and lumbar curvatures.

The goal of this study was to assess whether dancers of Spanish dance had better curvatures of the thoracic and lumbar spine than the rest of the population. The study assessed 34 students of Spanish dance from a professional dance conservatory, with an average age of 17.06 ± 2.86 years, and average practice time of 10.65 ± 3.41 years. The study measured the sagittal spinal curvatures of the dancers in a relaxed standing position. The measurements were performed using a uni-level inclinometer. The main findings revealed that the average thoracic kyphosis was 34.18 ± 5.10, and the average lumbar lordosis was 28.71 ± 4.91. The average values of the sagittal plane alignment of the thoracic and lumbar spine of the dancers in the standing position were normal, according to the scale proposed by Santoja (1993) and Contreras et al. (1981). There were no statistically significant differences; however, it was observed that the more advanced dance courses, the less thoracic and lumbar curvatures.

Association of low back pain and standing postural control (PC) deficits are reported inconsistently. Demands on PC adaptation strategies are increased by restraining the input of visual or somatosensory senses. The objectives of the current study are, to investigate whether PC adaptations of the spine, hip and the centre of pressure (COP) differ between patients reporting non-specific low back pain (NSLBP) and asymptomatic controls. The PC adaption strategies of the thoracic and lumbar spine, the hip and the COP were measured in fifty-seven NSLBP patients and 22 asymptomatic controls. We tested three "feet together" conditions with increasing demands on PC strategies, using inertial measurement units (IMUs) on the spine and a Wii balance board for centre of pressure (COP) parameters. The differences between NSLBP patients and controls were most apparent when the participants were blindfolded, but remaining on a firm surface. While NSLBP patients had larger thoracic and lumbar spine mean absolute deviations of position (MADpos) in the frontal plane, the same parameters decreased in control subjects (relative change (RC): 0.23, 95% confidence interval: 0.03 to 0.45 and 0.03 to 0.48). The Mean absolute deviation of velocity (MADvel) of the thoracic spine in the frontal plane showed a similar and significant effect (RC: 0.12 95% CI: 0.01 to 0.25). Gender, age and pain during the measurements affected some parameters significantly. PC adaptions differ between NSLBP patients and asymptomatic controls. The differences are most apparent for the thoracic and lumbar parameters of MADpos, in the frontal plane and while the visual condition was removed.

This thesis explores the design of systems that can climb vertical surfaces with non-negligible dynamics in the sagittal plane. The development of a low-dimensional model addresses a lack of understanding of sagittal plane dynamics during climbing in the space of reduced-order dynamic models of legged systems. Using a construction derived from the well-known and well-studied Spring-Loaded Inverted Pendulum (SLIP), we propose a two-legged system with both torsional and linear compliance driven by a position-controlled rotational actuator. Two simple foot models are considered to explore their effect on the dynamics and stability of the system. Results of the model indicate the existence of passively stable gaits during climbing as well as during inverted running and also suggest mechanical tuning parameters for physical climbing systems. A robotic platform capable of producing dynamic climbing behaviors is introduced. A reduced profile, sprawled posture, and improved internal mechanics allow the CLASH platform to be adapted to different climbing substrates. A passive claw engagement mechanism is proposed and tested with simulated steps to verify the design. With these mechanisms, CLASH becomes the first robotic platform capable of climbing loose cloth and climbs vertically at 15cm/s or 1.5 body-lengths per second. When climbing ferromagnetic surfaces, the system is capable of climbing at 1.8 body-lengths per second. To climb smooth, hard surfaces, a foot with a passively aligning ankle with a tendon-loaded gecko-inspired adhesive is designed and tested using simulated steps. With these engagement mechanisms, the system is able to climb at 1 body-length per second on acrylic with a 70-degree incline. A simple foot-impact model is created to explain the robot's inability to climb faster or up steeper inclines due to the sagittal plane reaction forces created during rapid running.

This thesis explores the design of systems that can climb vertical surfaces with non-negligible dynamics in the sagittal plane. The development of a low-dimensional model addresses a lack of understanding of sagittal plane dynamics during climbing in the space of reduced-order dynamic models of legged systems. Using a construction derived from the well-known and well-studied Spring-Loaded Inverted Pendulum (SLIP), we propose a two-legged system with both torsional and linear compliance driven by a position-controlled rotational actuator. Two simple foot models are considered to explore their effect on the dynamics and stability of the system. Results of the model indicate the existence of passively stable gaits during climbing as well as during inverted running and also suggest mechanical tuning parameters for physical climbing systems. A robotic platform capable of producing dynamic climbing behaviors is introduced. A reduced profile, sprawled posture, and improved internal mechanics allow the CLASH platform to be adapted to different climbing substrates. A passive claw engagement mechanism is proposed and tested with simulated steps to verify the design. With these mechanisms, CLASH becomes the first robotic platform capable of climbing loose cloth and climbs vertically at 15cm/s or 1.5 body-lengths per second. When climbing ferromagnetic surfaces, the system is capable of climbing at 1.8 body-lengths per second. To climb smooth, hard surfaces, a foot with a passively aligning ankle with a tendon-loaded gecko-inspired adhesive is designed and tested using simulated steps. With these engagement mechanisms, the system is able to climb at 1 body-length per second on acrylic with a 70-degree incline. A simple foot-impact model is created to explain the robot's inability to climb faster or up steeper inclines due to the sagittal plane reaction forces created during rapid running.

The existence of a range of optimal coefficient of friction that encompasses safety and comfort has not been addressed before. This paper assesses the existence of such a range and its relationship with the variability of human gait. Six women walked for 15 min over five ceramic tile floorings with friction coefficients (DCOF) ranging from 0.19 to 0.63. Subjective opinions (pain, comfort, etc.) and biomechanical parameters including sagittal plane knee angle, tibia acceleration, and ground reaction forces were gathered. The required coefficient of friction (RCOF) was calculated from ground reaction forces. The results show that as DCOF increases so do reports of pain in the knees and under the metatarsal heads and toes; whereas a low DCOF relates to pain in the thighs and perception of low friction. RCOF showed a quadratic relationship with DCOF indicating the existence of a range of optimal coefficient of friction outside of which walking strategy is modified either to avoid slipping (DCOF 0.55). This result is supported by the results of the analysis of gait variability using non-linear methods. Floors inside the optimal range of friction yielded statistically significant higher entropy for tibia acceleration and knee angle, confirming the hypothesis that gait is more constrained outside that range (i.e. natural variability is reduced).Relevance to the industry: Floor friction is one of the main concerns for the floor industry and for decision makers when choosing public space paving (indoor and outdoor). The false concept 'the more friction the better' can induce manufacturers and technicians to make wrong decisions. This paper can assist the industry produce and select solutions encompassing safety and comfort. © 2011 Elsevier B.V.

The three experiments reported here were tests of the effects of four variables upon the perception of the postural upright following body tilt in a forward or backward direction. The four variables studied were; (1) the degree of initial tilt, i.e., the degree to which the subject was tilted before being moved toward the vertical, (2) the time held at initial tilt, (3) the direction of initial tilt, and (4) the angular velocity of return. The fourth variable investigated in the present experiments, velocity of return, had not been evaluated before, nor had any one of the other three variables been studied systematically in the sagittal plane. Immediately bearing on the present report are certain studies dealing with the non-visual perception of the upright, most of which were conducted using lateral tilt. Briefly these reveal that: (a) the error of judgment of the upright is directly determined by the degree of initial tilt, increasing as an underestimation of the upright as the magnitude of initial tilt increases. (b) the error of judgment, either as an underestimation or an over-estimation of the vertical, does not differ significantly for the two directions of initial tilt within any one plane. (c) the error of underestimation of the vertical increases as the time held at the initial tilt increases.