Torque Control Apparatus Sensor Switching Delay
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Solution Overview
Problem
Existing torque control systems face challenges in accurately performing torque control while minimizing the influence of delays caused by low pass filters (LPFs) when switching between multiple torque sensors, as the continuous use of LPFs reduces processing rates and introduces unnecessary signal delays.
Innovation Solution
A torque control apparatus that includes a switching unit capable of switching between multiple torque sensors, using a first LPF for normal operation and a second LPF with a higher frequency only during sensor switching, which filters the signal for a predetermined period before reverting to direct output, thereby minimizing delay and suppressing sudden changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a low pass filter is provided after the stage at which torque sensors are switched, then the difference between output values for each sensor is reduced and resonance is suppressed, but the processing rate of the whole control system is reduced due to signal delay
Solution Approach 1:
The patent applies dynamics by making the low pass filter configuration changeable over time. Specifically, the system switches between two low pass filter settings: a first low pass filter with a lower cutoff frequency is used during normal operation to suppress resonance, while a second low pass filter with a higher cutoff frequency is activated during sensor switching transitions to minimize signal delay. This dynamic adjustment of filter characteristics resolves the contradiction between stability and processing rate.
Solution Approach 2:
The patent implements periodic action by alternating between different low pass filter configurations based on the operational state. During normal operation, the first low pass filter is continuously applied. When sensor switching is detected, the system periodically switches to the second low pass filter for the duration of the transition, then returns to the first filter configuration. This periodic switching of filter settings allows the system to maintain stability during normal operation while minimizing delay during critical switching transitions.
2Stability of the object's composition
If a low pass filter is used to pass torque sensor values, then resonance of devices connected by the torque sensors is removed, but the signal is delayed compared to the original signal
Solution Approach 1:
The patent applies local quality by using different low pass filter characteristics for different operational conditions. The first low pass filter with a lower cutoff frequency (e.g., 100 Hz) is used during normal operation to effectively suppress resonance. The second low pass filter with a higher cutoff frequency (e.g., 500 Hz) is used specifically during sensor switching transitions where signal delay must be minimized. This localized application of different filter qualities resolves the contradiction between resonance suppression and signal delay.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the cutoff frequency parameter of the low pass filter based on operational state. The system changes the filter parameter from a lower value (first low pass filter) during normal operation to a higher value (second low pass filter) during sensor switching. This parameter change allows the system to maintain effective resonance suppression when needed while minimizing signal delay during critical transitions.
Data Source
AI summary
A torque control apparatus includes a torque command output unit including a first low pass filter configured to cut off a torque command value by a first frequency, and a switching unit configured to switch, when a first torque value detected by a first torque sensor satisfies a predetermined condition, a second torque value detected by a second torque sensor to the torque command output unit. The switching unit includes a second low pass filter configured to cut off the second torque value by a second frequency which is higher than the first frequency and output the obtained value to the torque command output unit, uses the second low pass filter for a predetermined period of time after the switching, and outputs the second torque value to the torque command output unit without using the second low pass filter after the predetermined period of time has passed.