Clamping Force Estimation for a Brake-by-Wire Actuator

Estimating clamp force for brake-by-wire systems: Thermal considerations

“…To overcome these problems, the sensor can be embedded deep within the caliper. However, this leads to a hysteresis effect which causes a misleading clamp force to be sensed [8]. This hysteresis is caused by friction between the sensed location and inner pad.…”

“…5 that the characteristic curve varies with increased temperatures as a result of braking. Schwarz et al [8] algorithm for estimating clamp force has limitations for certain scenarios. One scenario is after vehicle braking has taken place followed by a period of cooling.…”

“…Therefore, a method to adjust the characteristic curve parameter values is required to handle pad wear. Schwarz et al [8] developed a method to achieve this, however some background detail is necessary before their approach can be explained.…”

“…Inertial torque is linearly proportional to the motor shaft acceleration (d 2 h m /dt 2 ) via a lumped inertia gain (J tot ) which is normally determined experimentally. Schwarz et al [8] use a torque balance approach to adapt characteristic curve parameter variations to accommodate for pad wear. They do not require a friction model within their use of the torque balance.…”

Analysis of a Regenerative Braking System for a Hybrid Electric Vehicle Using Electro-Mechanical Brakes

“…The loop has a low level control logic consisting of the current and velocity control loop shown in Figure 7. This structure requires particularly expensive sensors to measure the clamping force and braking torque; therefore, this paper uses a technique that estimates their values by sensing the voltage, current and position of the DC motor based on the dynamic model of the EMB (Schwarz et al, 1999). Figure 8 shows the EMB performance analysis simulator developed in this paper.…”