---

Due to necessity of increasing performance in new generations of the humanoid robots, in this paper, a novel power transmission mechanism to actuate the ankle joint of a humanoid robot is presented in order to increase the motion speed of SURENAIII humanoid robot. Also, the energy consumption of the proposed and the previous mechanisms are studied. In the proposed mechanism, the actuators of the ankle joint are located in the shank link. Then, a combined timing belt-pulley and a harmonic drive module are exploited for power transmission for the pitch joint. Also, the roll joint drive has employed a roller screw. In order to validate the design procedure, the simulation results of the robot are compared with the experimental data. The results reveal that the dynamic model is fairly matched to the real behavior of the robot. Also, the revolutionary genetic algorithm is employed to optimize the effective path planning parameters with respect to the minimum knee joint torque. This optimization procedure which is employed in robot walking on flat terrains consist of straight motion, ensures the robot's stability. As a result, the optimal path planning parameters for proposed mechanism are obtained in such a way that has decreased the actuating torques of lower-body of SURENAIII. Also, the proposed mechanism can achieve using lighter motors and getting the robot faster by means of mass reduction of foot.

---

In recent years, knee diseases are spread especially in elderly people. Since performing daily activities such as walking and running, the knee supports the weight of the body, there is more likely to be injured. This issue is more important for elderly people who have weak muscles and almost all elderly people suffer from knee pain. One way to help this people in order to move normally is to use a wearable device to aid the knee. In this article, a passive wearable robot will be designed to improve the strength of the elderly who suffers from the knee pain. The robot uses the compliance elements to increase the power of the knee joint in parts of a cycle. This robot will be developed based on a Stephenson II six-bar mechanism. Using this mechanism has the advantage of producing the similar motion to a knee. In other words, this mechanism produces the linear and rotational motions simultaneously. Additionally, more compliance elements can be added to improve the performance of the wearable robot. The optimal dimensions of the robot will be Through the kinematics analysis and also the derivation of the dynamics equations and the numerical validations of these equations, the performance of the robot will be considered. The performance of the robot mounted on the leg is compared with the human. Obtained results show that the less power is required when a wearable robot is used. This proves the merits of the designed robot to be used for the elderly.

---

Introduction: Osteoarthritis is the most common type of arthritis and is one of the most common causes of pain and disability in adults. In the present study we investigated the level of inflammatory cytokines IL-1β and TNF-α and the amount of joint friction after non-traumatic model of knee osteoarthrosis in guinea pig.
Materials & Methods: Twenty-four matured albino male Dunkin-Hartley guinea pigs were assigned randomly into two groups; osteoarthrosis (OA) and control (n=12 in each group). The non-traumatic OA was induced by intra-articular injection of mono iodoacetate (MIA, 3 mg/kg) in the knee joint. Joint circumstance and weight of subjects were measured initially and after thirty days of MIA injection. After scarifying the animals on day 30, the level of IL-1β and TNF-α in synovial membrane and knee joint friction were measured. Control group received no intervention and all evaluations were performed on the normal knee joint.
Results: The induction of OA caused a significant increase in the joint circumstance compared to control group (P<0.05). 30 days after induced OA, the knee joint friction in flexion and extension movement was significantly increased compared to control group.  In OA group, the level of IL-1β and TNF-α showed a significant increase compared to control group (P<0.05). There was a positive correlation between IL-1β, TNF-α and knee joint friction (P<0.01).
Discussion: Non-traumatic osteoarthritis may increase the expression of inflammatory cytokines and joint friction, which in this condition the joint movement can aggravate cartilage damage.