A new cool-tip radiofrequency (RF) ablation therapeutic instrument based on impedance control algorithm is introduced in this paper. The equipment is composed of hardware system and software system. The RF power output and real time data acquisition are completed by the hardware system, while the software is used mainly to finish the control of the ablation range, the core of which is impedance control algorithm, and it also used to complete the display of the real time data in the course of the experiment. The impedance algorithm has solved the problem of impedance increased rapidly during the RF ablation, which has also expanded the scope of ablation. The pig liver experiments showed that the impedance control algorithm had strong adaptability. It also obtained a result of ablation range up to 3.5~4.5 cm single needle. It has the high clinical practical value of one-time inactivation of 3~5 cm tumor.
In order to stimulate the patients' active participation in the process of robot-assisted rehabilitation training of stroke patients, the rehabilitation robots should provide assistant torque to patients according to their rehabilitation needs. This paper proposed an assist-as-needed control strategy for wrist rehabilitation robots. Firstly, the ability evaluation rules were formulated and the patient's ability was evaluated according to the rules. Then the controller was designed. Based on the evaluation results, the controller can calculate the assistant torque needed by the patient to complete the rehabilitation training task and send commands to motor. Finally, the motor is controlled to output the commanded value, which assists the patient to complete the rehabilitation training task. The control strategy was implemented to the wrist function rehabilitation robot, which could achieve the training effect of assist-as-needed and could avoid the surge of assistance torque. In addition, therapists can adjust multiple parameters in the ability evaluation rules online to customize the difficulty of tasks for patients with different rehabilitation status. The method proposed in this paper does not rely on the information from force sensor, which reduces development costs and is easy to implement.