Algorithm for power drive speed control
First Claim
1. A control system for a self-propelled patient-support apparatus comprisinga user input device,a motor for driving a wheel over a floor, anda controller including a processor and a memory device including instructions that, when executed by the processor, (i) monitor the user input device to determine a speed input request from a user, (ii) determine a desired direction of movement of the patient-support apparatus across the floor, (iii) normalize the speed input request, (iv) compare the normalized speed input request to a threshold value, (v) calculate an effective speed input value by evaluating a current speed input request and a previous speed output value, (vi) apply a speed transfer function to the effective speed input value to determine a current raw speed output value, (vii) scale the current raw speed output value based on the desired direction of movement to determine a current scaled speed output, (viii) weight the current scaled speed output with the previous speed output value to determine a current speed output value to transmit to the motor.
5 Assignments
0 Petitions
Accused Products
Abstract
A control system for a self-propelled patient-support apparatus includes a controller that utilizes a power drive speed control algorithm to control the power output to a motor of a drive mechanism for driving the patient-support apparatus across a floor. The control algorithm normalizes a force input by a user on a user input device, the force indicative of a desired drive speed. The algorithm varies the responsiveness of the output to the drive mechanism based on the current operating conditions of the drive mechanism.
-
Citations
21 Claims
-
1. A control system for a self-propelled patient-support apparatus comprising
a user input device, a motor for driving a wheel over a floor, and a controller including a processor and a memory device including instructions that, when executed by the processor, (i) monitor the user input device to determine a speed input request from a user, (ii) determine a desired direction of movement of the patient-support apparatus across the floor, (iii) normalize the speed input request, (iv) compare the normalized speed input request to a threshold value, (v) calculate an effective speed input value by evaluating a current speed input request and a previous speed output value, (vi) apply a speed transfer function to the effective speed input value to determine a current raw speed output value, (vii) scale the current raw speed output value based on the desired direction of movement to determine a current scaled speed output, (viii) weight the current scaled speed output with the previous speed output value to determine a current speed output value to transmit to the motor.
-
13. A patient-support apparatus comprising
a frame, a drive mechanism coupled to the frame and configured to move the patient-support apparatus across a floor, the drive mechanism including a drive wheel and a motor to drive the wheel, a controller coupled to the motor, and a user input coupled to the controller and configured to provide an input indicative of the speed and direction a user wishes to move the patient-support apparatus, wherein the controller includes a processor and a memory device including instructions that, when executed by the processor, (i) monitor the user input device to determine a speed input request from a user, (ii) determine a desired direction of movement of the patient-support apparatus across the floor, (iii) normalize the speed input request, (iv) compare the normalized speed input request to a threshold value, (v) calculate an effective speed input value by evaluating a current speed input request and a previous speed output value, (vi) apply a speed transfer function to the effective speed input value to determine a current raw speed output value, (vii) scale the current raw speed output value based on the desired direction of movement to determine a current scaled speed output, (viii) weight the current scaled speed output with the previous speed output value to determine a current speed output value to transmit to the motor.
-
15. A method of controlling the speed and direction of travel of a self-propelled patient-support apparatus including a variable user input device configured to receive a user input indicative of the direction and speed of travel, the method comprising the steps of
monitoring the variable user input device to determine a speed input request from a user, determining a desired direction of movement of the patient-support apparatus, normalizing the speed input request, comparing the normalized speed input request to a threshold value, calculating an effective speed input value by evaluating a current speed input request and a previous speed output value, applying a speed transfer function to the effective input to determine a current raw speed output value, scaling the current raw speed output value based on the desired direction of movement to determine a current scaled speed output, and weighting the current scaled speed output with the previous speed output value to determine a current speed output value to transmit to a motor.
Specification