Methods and apparatus to determine loads encountered by a steering rack
Methods and apparatus to determine rack force are disclosed. An example apparatus includes a rack to couple to a steering knuckle of a vehicle, a ball nut engaged with the rack, a first ring gear coupled to the ball nut, a first pinion fixed to a motor, the first pinion engaged with the first ring gear, the motor to rotate the ball nut to move the rack, a motor encoder to detect a rotation of the first pinion, a second ring gear coupled to the ball nut, and a sensor fixed to a second pinion, the second pinion engaged with the second ring gear, the second pinion to rotate as the second ring gear rotates, the sensor to detect a rotation of the second pinion, the rotation of the second pinion and the rotation of the first pinion corresponding to a force on the rack.
1. An apparatus comprising:
a rotary encoder to generate a first signal based on a position of a motor shaft that includes a first pinion engaged with a first ring gear;
a sensor to generate a second signal based on a rotation of a second pinion that is engaged with a second ring gear;
machine readable instructions; and
processor circuitry configured to execute or execute the machine readable instructions to determine a load on a steering rack of a vehicle based on the first signal and the second signal.
2. The apparatus of claim 1 , wherein the processor circuitry is to control a torque on a steering wheel based on the load.
3. The apparatus of claim 1 , wherein the processor circuitry is to:
determine a first position of the steering rack based on the first signal;
determine a second position of the steering rack based on the second signal;
when the first position is different from the second position, determine the steering rack has a non-zero load; and
when the first position matches the second position, determine the load is zero.
4. The apparatus of claim 3 , wherein, when the first position is different from the second position, the processor circuitry is to determine a value of the non-zero load based on a difference between the first position and the second position.
5. The apparatus of claim 4 , wherein, when the first position is different from the second position, the processor circuitry is to determine the value of the non-zero load based on a spring rate of a spring that resists linear movement of the first ring gear and the second ring gear.
6. The apparatus of claim 1 , wherein the processor circuitry is to determine a steering angle implemented by wheels of the vehicle based on at least one of the first signal or the second signal.
7. The apparatus of claim 6 , wherein the processor circuitry is to:
determine whether the steering angle matches a target steering angle associated with a position of a steering wheel; and
when the steering angle is different from the target steering angle, control an output of a motor to adjust the steering angle based on a difference between the steering angle and the target steering angle.
8. A non-transitory machine readable storage medium comprising instructions to cause processor circuitry to at least determine a load encountered by a steering rack of a vehicle based on (i) a first signal corresponding to a position of a motor shaft and (ii) a second signal corresponding to a rotation of a pinion separate from the motor shaft.
9. The non-transitory machine readable storage medium of claim 8 , wherein the instructions cause the processor circuitry to control a torque on a steering wheel based on the load.
10. The non-transitory machine readable storage medium of claim 8 , wherein the instructions cause the processor circuitry to:
determine a first position of the steering rack based on the first signal;
determine a second position of the steering rack based on the second signal;
when the first position is different from the second position, determine the steering rack has a non-zero load; and
when the first position matches the second position, determine the load is zero.
11. The non-transitory machine readable storage medium of claim 10 , wherein, when the first position is different from the second position, the instructions cause the processor circuitry to determine a value of the non-zero load based on a difference between the first position and the second position.
12. The non-transitory machine readable storage medium of claim 11 , wherein, when the first position is different from the second position, the instructions cause the processor circuitry to determine the value of the non-zero load based on a spring rate of a spring that resists linear movement of a geared thrust bearing engaged with the motor shaft and the pinion.
13. The non-transitory machine readable storage medium of claim 8 , wherein the instructions cause the processor circuitry to determine a steering angle implemented by wheels of the vehicle based on at least one of the first signal or the second signal.
14. The non-transitory machine readable storage medium of claim 13 , wherein the instructions cause the processor circuitry to:
determine whether the steering angle matches a target steering angle associated with a position of a steering wheel; and
when the steering angle is different from the target steering angle, control an output of a motor to adjust the steering angle based on a difference between the steering angle and the target steering angle.
15. A method comprising:
determining a load encountered by a steering rack of a vehicle based on (i) a first signal corresponding to a position of a motor shaft and (ii) a second signal corresponding to a rotation of a pinion separate from the motor shaft.
16. The method of claim 15 , further including controlling a torque on a steering wheel based on the load.
17. The method of claim 15 , further including:
determining a first position of the steering rack based on the first signal;
determining a second position of the steering rack based on the second signal;
when the first position is different from the second position, determining the steering rack has a non-zero load; and
when the first position matches the second position, determining the load is zero.
18. The method of claim 17 , further including, when the first position is different from the second position, determining a value of the non-zero load based on a difference between the first position and the second position.
19. The method of claim 18 , further including, when the first position is different from the second position, determining the value of the non-zero load based on a spring rate of a spring that resists linear movement of a geared thrust bearing engaged with the motor shaft and the pinion.
20. The method of claim 15 , further including:
determining a steering angle implemented by wheels of the vehicle based on at least one of the first signal or the second signal;
determining whether the steering angle matches a target steering angle associated with a position of a steering wheel; and
when the steering angle is different from the target steering angle, adjusting an output of a motor to cause an adjustment to the steering angle based on a difference between the steering angle and the target steering angle.