Research on Friction Compensation Control for Electric Power Steering System

A novel friction compensation control method is proposed to compensate both the dynamic and static friction torque of steering system. The change of EPS assist torque under fixed amplitude friction compensation torque can cause the diver’s steering feeling fuzzy. That is due to the fact that the friction torque felt by driver varies with EPS assist gain. Therefore, a further modified friction compensation control method is proposed based on EPS assist gain to make the driver have similar friction feeling. Finally, computer simulation and vehicle test are performed to verify the effectiveness of adaptation method in the proposed controller. Test results indicate that the proposed controller improved the driver’s steering performance

Slip Control of Electric Vehicle Based on Tire-Road Friction Coefficient Estimation

The real-time change of tire-road friction coefficient is one of the important factors that influence vehicle safety performance. Besides, the vehicle wheels’ locking up has become an important issue. In order to solve these problems, this paper comes up with a novel slip control of electric vehicle (EV) based on tire-road friction coefficient estimation. First and foremost, a novel method is proposed to estimate the tire-road friction coefficient, and then the reference slip ratio is determined based on the estimation results. Finally, with the reference slip ratio, a slip control based on model predictive control (MPC) is designed to prevent the vehicle wheels from locking up. In this regard, the proposed controller guarantees the optimal braking torque on each wheel by individually controlling the slip ratio of each tire within the stable zone. Theoretical analyses and simulation show that the proposed controller is effective for better braking performance

Improvement in the Thermal Stability of Pyrophosphatase by Conjugation to Poly(<i>N</i>‑isopropylacrylamide): Application to the Polymerase Chain Reaction

Polymerase chain reaction (PCR) is a powerful method for nucleic acid amplification. However, the PCR is inhibited in its yield due to its byproduct, pyrophosphate (PPi), a byproduct of the reaction; the yield is thereby limited. The conventional method for hydrolysis of PPi by pyrophosphatase (PPase) is not well adapted for operation at elevated temperatures over long times as required during the PCR. In this work, we reported a strategy to improve the PCR yield using a conjugate of the enzyme with the thermally responsive polymer poly­(<i>N</i>-isopropylacrylamide) (PNIPAM). Pyrophosphatase (PPase) was conjugated to PNIPAM site-specifically near the active center. As compared to the free enzyme, the optimum temperature of the conjugate was shown to increase from 45 to 60 °C. For the conjugate, about 77% enzyme activity was retained after incubation at 60 °C for 3 h, representing a 6.8-fold increase as compared to the unconjugated enzyme. For the PCR using the conjugate, the yield was 1.5-fold greater than using the unconjugated enzyme. As well as improving the yield of the PCR (and possibly other biological reactions) at elevated temperature, polymer conjugation may also provide a strategy to improve the heat resistance of proteins more generally

6G Near-field Technologies White Paper

No abstract available