Yan Jihong

Autonomous Kinematic Self-Calibration of a Novel Haptic Device

A closed loop self-calibration method for Delta mechanism and 3-RRR mechanism used in a double parallel haptic device was presented. This approach blocks successively one joint of each parallel mechanism using a simple lockup device and reforms the 3-DOF mechanism to be a 2-DOF one. The parameter errors of the mechanism are identified according to the differences between the sensor output of the redundant chain and nominal model output. Both the condition number and singular value of the error propagation Jacobian are synthesized as a new selection principle of calibration set such that the calibrating process is insensitive to the noise and the calibration precision is increased efficiently. Experiments show that the ratio of maximal error before and after calibrating is 9.6, namely, the setting accuracy of the two mechanisms are increased about 10 times and the error of re-position is less than 0.1 mm and 0.1deg

Coordinated controller of Internet-based multi telerobot cooperation

Time delay over the Internet deteriorates the performance of multi-operator-multi-robot teleoperation system (MOMR). At present, several methods aiming at the problems of the Internet-based multi-telerobot collaboration only depend on the master side. In this paper, a coordinated controller was presented based on the idea of shared control that combined the intelligence of the master side with the slave side. It is composed of three modules, task coordination, motion planning and communication, which can not only increase the efficiency and safety of the system but also relieve the burden and the requirements to the operators. The controller also can cope with the collision between two telerobots in the common environment arising from the time delay. A simulation experiment via an Ethernet local area network (LAN) subject to simulated time delay was carried out to protect the medical staff from highly dangerous virus such as SARS, bird flu etc. And the validity of the coordinated controller was evaluated in the system.

SMA-based space release device for solar panels deployment

Most of separating operations for solar panels have been achieved by utilizing explosive bolt nowadays. However, with the development of space technology, especially when new generations of small satellites start to emerge, traditional pyrotechnical products cannot provide spacecrafts with satisfied performance, since the fierce shock and contamination are not avoidable. Thus, developing novel types of non-pyrotechnical actuators has become the research focus for release mechanism. In this paper, we propose to adopt the memory effect of the shape memory alloy (SMA) for developing release devices. Brinson theory has been chosen as the theoretical foundation of performance analysis. This new type of mechanism mitigates the problem of shock and contamination, meanwhile possessing several excellent advantages such as compact volume, quick response, outstanding synchronism and reusability.