The authors have developed a shoulder joint model considering RRR type serial manipulator. The servo motors are placed in such a way that they are dynamically balanced. For estimating the torques for each motor L-E method is employed. The joint architecture developed depicts circumduction, pronation and supination and abduction and adduction. Torque values are obtained both analytically and practically. Graphs are plotted and the results obtained are supportive to consider the joint for rehabilitation.

(далее…)

Категория: Научные статьи | Нет комментариев »

A study concerning the children locomotion system is presented through this research. The research aim is to obtain the motion laws developed by the children locomotion system’s articulations and connection forces which are produced in their structure in the walking activity. These parameters are useful for orthotic and prosthetic systems design for children with ages between 4-7 years. The study is based on an experimental analysis developed with ultra highspeed video equipment on 20 children and a dynamic analysis achieved on analytical way by using the results obtained from the experimental analysis. A new knee modular orthosis and a parameterized lower limb are designed through this research.

(далее…)

Категория: Научные статьи | Нет комментариев »

The foot-ground contact force is one of the important factors affecting the gait behaviour, balance and safety of a bipedal robotic mechanism. This force is constrained by the coefficient of friction of the foot-ground contact. This coefficient of friction is thus of high importance, as non-sliding contact and/or the knowledge of the coefficient of friction of the foot-ground contact are common assumptions among bipedal robotics literature. Failure to keep the ratio of the fric-tion force to normal force of the foot-ground contact below the coefficient of friction causes the foot to slip, resulting in a large external disturbance being applied to the biped and causing the bipedal robot to lose balance and fall. In this work an online estimation technique for estimating the coefficient of friction of the foot-ground contact is developed. It is expected that the estimation algorithm converges to the value of the coefficient of friction of the contact before the ratio of the friction and normal forces exceeds the coefficient of friction, thus allowing the robot control strategy to avoid slipping altogether by altering the forces exerted by the robot actuation. The proposed estimator is validated experimentally using real-world materials. The estimator is shown to be able to determine the coefficient of friction of the materials ahead of the applied force ratio exceeding the coefficient of friction. Finally a 6-link bipedal robot is modelled and a slip prevention algorithm based on the estimator is implemented to illustrate how a bipedal robot would be able to avoid slipping while walking on a surface of unknown coefficient of friction. The bipedal gait is achieved using a previously developed control algorithm and walks on two flat surfaces of unknown coefficients of friction under ideal simulated conditions. The resulting simulations are compared to demonstrate the effectiveness of the proposed approach. The bipedal robot is shown to be able to walk on a surface of coefficient of friction of 0.4 without slipping and without prior knowledge of this value.

(далее…)

Категория: Научные статьи | Нет комментариев »

This thesis details the design and fabrication of an advanced, hydrauli-cally actuated exoskeleton, with the intention of decreasing weight and increasing performance over a previous proof of concept device. The initial device was invented to provide a method of gait restoration to individuals with paraplegia. It combines two different ideas – functional electrical stimulation of the user’s muscles, and an external, hydraulically actuated exoskeleton. By incorporating the user’s own muscles, this method is theoretically more energy efficient than other alternatives while providing addi-tional health benefits. However, in order to fully realize these advantages, the device must be made smal-ler and lighter, in order to decrease the overhead energy requirements placed on the user’s own muscular system. To accomplish this, a new exoskeleton was designed, that utilizes all off the advanced manu-facturing and fabrication resources of the department. Part count has decreased at the cost of manu-facturing complexity, and the use of aluminum and carbon fiber composite material is now prevalent in the device. Neither the hydraulic system nor the controller was modified in any way during this process. The end result of this work is a substantial decrease in overall unit weight (30%), and an estimated decrease in user energy requirements of approximately 15.2%. This was accomplished while maintaining all previous benchmarks in range of motion. It is expected that this will have a positive influence on the operation of the device, particularly in planned future endeavors in stair climbing. Future work in this area to further increase device performance can take place in integration and redesign of all hydraulic components – replacing the existing brass pieces with lightweight, high operating pressure, potentially seal free pieces made from high strength, aerospace grade 7000 series aluminum.

(далее…)

Категория: Научные статьи | Нет комментариев »

Patients suffering from below knee amputation utilize ankle-foot prostheses to regain partial mobility. Research efforts have focused on improving device functionality to offer patients a higher standard of living. This study proposes a novel algorithm for device control, which utilizes input from two sensors to relay data into the control system. The system processes the data according to a set of rules, and outputs a respective foot angle value to mimic the normal motion of the ankle-foot complex in natural cadence. Matlab Simulink offers exceptional utility in developing a computa-tional model for evaluating the efficacy of the rule system. Comparison of the true and theoretical foot angle values produced low levels of error underlining the overall effectiveness of the algorithm.

(далее…)

Категория: Научные статьи | Нет комментариев »