Joint Velocity and Acceleration Estimation in Serial Chain Rigid Body and Flexible Joint Manipulators This paper deals with the problem of accurately computing and estimating joint velocity and acceleration in robotic manipulators. Generally, it is well known that numerical differentiation of noisy position signals even with significant filtering is no viable solution. This is especially true for computing joint acceleration. Specifically, our solution to this problem fuses joint position measurement with link accelerometers, which are affordable and easy to install. Since the sensor readings are affected by noise, drift and bias, suitable data fusion and filtering methods are proposed for improving the estimation for practical use. Simulation results based on a realistic dynamics model of a 7DoF robot including various parasitic effects and experimental results with a 7DoF robot demonstrate the effectiveness of our approach. This method would have multiple use, e.g., in monitoring external joint torques and handle possibly unforeseen collisions. Furthermore, other applications such as load identification and compensation as well as state feedback linearization for flexible joint robots could finally become possible also practical.

Joint Torque Estimation for Dynamic Jumping Control of Compliant GearDriven Legged Robot * This paper is to explain compliant torque control for gear driven legged robot. In this paper, active torque compliance control is realized without torque sensor or any mechanically elastic component. The joint torque estimation is very important for torque control. However, Joint torque sensor for mediumsize legged robot is so large and heavy that it increases the inertia of the leg, slows down the dynamic response, and leads to complicated electrical system. Therefore, we only use the encoder information and the motor current to estimate the joint torque without torque sensors. Compliant torque control have advantages of absorbing impacts and saving energy. But, torque control is difficult to guarantee the position precision, because the accurate model of the robot is hard to obtain. In order to ensure both compliance and position accuracy, hybrid torque and position control is applied to our robot. In the jumping motion experiments, it is verified that the joint torque can reach peck value in 4.75 ms when jumping up. While The landing peak torque in hybrid control is lower than 16 of that under position control and 12 of that in torque control. This indicates that the compliance torque control can absorb a large part of shock.