The Kinematic and Dynamic Modeling and Numerical Calculation of Robots with Complex Mechanisms Based on Lie Group Theory

The kinematic and dynamic models of robots with complex mechanisms such as the closed-chain mechanism and the branch mechanism are often very complex and difficult to be calculated. Aiming at this issue, in this paper, the pose of the component in robots is represented by the Euclidean group and its subgroups with the proposed method. The component’s velocity is derived using the relationship between the Lie group and Lie algebra, and the acceleration and Jacobian matrix are then derived on this basis. The Lagrange equation is expressed by the obtained kinematic parameter expressions. Establishing the model with this method can obtain clear physical meaning and make the expressions uniform and easy to program, which is convenient for computer-aided calculation and parameterization. Calculating by the properties of the Lie group can reduce the calculation and model complexity, especially for calculating the velocity and acceleration, which reduces the calculation error and eases the calculation. Therefore, the proposed modeling and calculation method of kinematics and dynamics of robots is especially suitable for robots with complex mechanisms. As an example, the kinematic and dynamic model of the manipulator developed in our laboratory is established and a working process of it is numerically calculated. Then, the results of the numerical calculation are compared with the results of virtual prototype simulation in ADAMS to verify the correctness.

Use of the kinematic radius in the rolling mechanics of an elastic wheel

The analysis of the physical essence of the kinematic and dynamic radii of the wheel is given. It is stated that the rolling radius of the wheel is a conditional kinematic parameter that characterizes only the rolling mode of the wheel. It is not the shoulder of all longitudinal forces acting on the wheel and should not be used to determine tractive forces, rolling resistance and wheel braking forces. Specific examples are given to illustrate the inappropriateness of using the kinematic radius to determine forces and moments. Keywords: elastic wheel, rolling radius, kinematic radius, dynamic radius, arm of force, traction force, rolling resistance force, braking force, rolling mode

OPTIMIZATION TECHNIQUE OF DRIVING DISC PARAMETERS

Flat circular discs in powered operation mode create driving forces. These forces enable to decrease the wheel slippage of the energy saturated tractor of tillage unit and to reduce the specific energy consumption. The objective of this study was to develop a technique that enables to determine the driving disc optimal parameters for maximum efficiency criterion. The earlier developed mathematical model of soil-disc interaction was used for this purpose. Soil properties in the model are characterized by means of two empirical constants. The relative depth and the kinematic parameter determine the disc operation mode. It was shown that the driving disc can operate with high efficiency, if the disc operates at the optimal values of the parameters. The driving disc efficiency can achieve the value about fifty percent. The experimental results confirmed the adequacy of the technique. The discrepancy between the predicted and field experimental values of driving forces and applied moments was about 25%. The proposed technique can be modified to optimize the parameters of other powered rotary tools of tillage machines and units.

AMRTA-X: Grasp Kinematic Analysis during Myoelectric Prehension Orthosis and Body Powered Prehension Orthosis's Usage on Brachial Plexus Injury Patients

Brachial Plexus Injury (BPI) results in decreased motor function in upper extremity and leads to reduced hand grasping movement. Orthotic prehension is designed to create artificial grasp movements in paralyzed hand. This study was to compare grasp kinematic improvement between body powered and myoelectric prehension orthosis usage in patients with BPI. This study was a single group without control and post test with experimental study. The subjects of the study (n = 11) were brachial plexus injury patients with non-functional hand strength. Joint motion and angular velocity of metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joint of index finger were evaluated. There was an improvement in joint motion and angular velocity after both orthosis usage. Joint motion in MCP and PIP, Angular velocity in MCP were not significantly different between myoelectric and body powered and myoelectric prehension orthosis usage. PIP angular velocity improvement were better after body powered prehension orthosis usage (p= 0.03).In conclusion, body powered and myolectric prehension orthosis usage improved kinematic parameter of index finger’s MCP and PIP joint. PIP angular velocity was better after body powered prehension orthosis usage.

Breath-Jockey: Development and Feasibility Assessment of a Wearable System for Respiratory Rate and Kinematic Parameter Estimation for Gallop Athletes

In recent years, wearable devices for physiological parameter monitoring in sports and physical activities have been gaining momentum. In particular, some studies have focused their attention on using available commercial monitoring systems mainly on horses during training sessions or competitions. Only a few studies have focused on the jockey’s physiological and kinematic parameters. Although at a glance, it seems jockeys do not make a lot of effort during riding, it is quite the opposite. Indeed, especially during competitions, they profuse a short but high intensity effort. To this extend, we propose a wearable system integrating conductive textiles and an M-IMU to simultaneously monitor the respiratory rate (RR) and kinematic parameters of the riding activity. Firstly, we tested the developed wearable system on a healthy volunteer mimicking the typical riding movements of jockeys and compared the performances with a reference instrument. Lastly, we tested the system on two gallop jockeys during the “137∘ Derby Italiano di Galoppo”. The proposed system is able to track both the RR and the kinematic parameters during the various phases of the competition both at rest and during the race.