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Development of motor actuated antilock brake system for light weight motorcycle
JSAE Review 19 (1998) 373—377
New Technologies & New Cars
Development of motor actuated antilock brake system for light weight motorcycle Takeshi Wakabayashi!, Takushi Matsuto!, Kazhuiko Tani", Atsuo Ohta! ! Engineering Design Department, Honda R&D Co. Ltd., Asaka R&D Center, 3-15-1 Senzui Asaka, Saitama, 351-8555 Japan " Engineering Research Department, Honda R&D Co. Ltd., Asaka R&D Center, 3-15-1 Senzui Asaka, Saitama, 351-8555 Japan Received 6 April 1998
Abstract A brake system with the function of a Combined Brake System on the rear brake which distributes the controlled braking force to the front, and an Antilock Brake System on front and rear brakes was developed for the light weight motorcycle. Using a single channel actuator which consists of a reversible motor, an electromagnetic brake, a double planetary differential gear, etc., this brake system has achieved a low cost and small size, and was applied successfully to a 50 cc scooter. ( 1998 Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved.
1. Introduction
2. Outline of M.A.-C. ABS
The Motor Actuated Combined Antilock Brake System (hereinafter refered to as M.A.-C. ABS), as shown in Fig. 1, for light weight motorcycles was developed aiming to release riders from the anxiety of a wheel lock during braking and to provide an easy to operate brake system with higher braking efficiency. The first objective was achieved by adopting ABS, and the second was achieved by the Combined Brake System (hereinafter referred to as CBS). The CBS for motorcycles ensures optimum brake force distribution simultaneously to the front and rear wheels by operation of just one brake lever. The M.A.-C. ABS is a combination of ABS and CBS. This combination results in a simple, compact and inexpective system with a reduced number of parts which makes a light weight motorcycle possible. (For more information, see [1—4].) This M.A.-C. ABS was applied to the scooter “Live Dio ST” with 50 cc-engine displacement shown in Fig. 2, and put onto the Japanese market from 1996.
2.1. Composition of M.A.- C. ABS Fig. 3. shows the arrangement of the components of the M.A.-C. ABS. Fig. 4 shows a diagram of the actuator and the cable damper. The M.A.-C. ABS has a single actuator. The actuator makes the CBS and the ABS compatible by controlling rotation direction and force of a single motor. 1. Independently actuated brake systems for the front and rear wheels: A hydraulic disk brake is adopted for the front wheel and a cable type drum brake is adopted for the rear wheel. Primary brake cables are used between both levers and actuator. 2. Actuator: The actuator is arranged between the levers and the front and rear brakes. The actuato r is composed of a reversible motor, and electromagnetic brake, a double planetary differential gear, front and rear brake control arms, an angle sensor, etc.
0389-4304/98/$19.00 ( 1998 Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved. PII: S 0 3 8 9 - 4 3 0 4 ( 9 8 ) 0 0 0 3 4 - 4
JSAE9835393
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T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377
Fig. 1. Motor actuated combined antilock brake system.
Fig. 3. Installation of M.A.-C. ABS.
Fig. 2. Live Dio ST.
3. Cable damper: The cable dampers are arranged on each of the primary brake cables which connect the levers and the actuator. The cable dampers are composed of a limit switch that operates when a certain cable tension is applied and springs to decrease the lever pulsation when the ABS operates. 4. ECU: The ECU consists of an 8 bit-CPU which controls the CBS and ABS and a motor drive circuit, and performs self diagnosis in addition to diagnosing the
entire system. The indicator lamp flashes when the ECU detects any abnormality of the system. 2.2. Operation principle of the M.A.-C ABS The CBS operates only when an input force is given to the left lever. The actuator generates the front wheel braking force according to the input force. Fig. 5 shows the relation of the distribution between front and rear wheel braking force. The left lever input is transmitted to the rear drum brake by the cable damper and the rear brake control
T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377
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Fig. 4. Actuator and cable damper.
arm. After the limit switch of the cable damper operates, the angle sensor of the actuator detects the operation angle of the rear brake control arm as a stroke of the left lever operation. The wheel speed sensors detect the rotation pulse of the front and rear wheels. These signals are transmitted to the ECU. To operate the actuator, the ECU sends the current to the electromagnetic brake of the actuator and the motor at the same time. The amount of motor current is calculated by the ECU based on the operation of the left lever input condition, the play of rear brake cable, the vehicle speed, etc. The motor rotates the front brake control arm according to the current value and generates the front braking force. During ABS operation, the motor of the actuator rotates in the opposite direction to that during CBS operation. The motor torque is transmitted in the direction where front and rear braking force is reduced and it controls the front and rear braking force at the time at a predetermined rate. The ECU calculates the slip ration and the deceleration of the front and rear wheels based on the signal sent from each wheel speed sensor. The ECU sends the signals of current of the electromagnetic brake to the actuator and the current necessary to avoid wheel locking to the motor. At this time, the internal springs of the cable dampers contract when the tension of the brake cable becomes above a certain value, and decrease the lever pulsation. When the ECU detects the recovery of the front and rear wheels slip ratio, it decreases the motor torque and increases the braking force again. Repeating the above operation, the actuator controls the braking force until the motorcycle almost stops or the input force is released.
2.3. Control of M.A.-C. ABS The maximum deceleration on each type of road surface condition is generated based on the ideal braking force distribution curve shown in Fig. 5. However, the CBS characteristic of M.A.-C. ABS is set increasing the rear braking force compared with the ideal distribution curve. This is a setting to assure locking of the rear wheel first, when there is an excessive input from the left lever to the rear brake. When the left lever is operated, the limit switch of the cable damper operates at point A shown in Fig. 5 and the actuator starts to generate additional front braking force. The amount of front braking force to be added is controlled responding to the state of lever operation by the rider, the vehicle speed, etc. The ABS of M.A.-C. ABS is a single channel control system. In this single channel control, when either the front wheel or rear wheel is locked, both brakes are operated by the ABS at the same time. The rear wheel slip ratio is determined by the calculation result of the ECU. The operation point of the ABS on the rear wheel is decided by the ECU judging if the road surface is slippery or not according to the relation between the differentiation value of the rear wheel slip ratio and the input force. Therefore the braking performance and the motorcycle control for various road surface conditions are assured. Moreover, the M.A.-C. ABS has a dead zone where neither the ABS nor the CBS operate, so that the brake operation changes smoothly when the control changes from the ABS to the CBS. The ABS operation repeats the process where the braking force decreases and the process where the
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T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377 Table 1 Specification of test motorcycle Items
Motorcycle A Motorcycle B
Brake system
M.A.-C. ABS
Wheel base : ¸ (m) Curb mass : M (kg) Height of C.G. : H (m) Distance between C.G. and rear axle : X (m) Distributed load of motorcycle wilth one rider, front/rear (N)
1.148 79.7 0.622
Conventional brake 1.148 74.5 0.612
0.714
0.716
525/822
464/831
Fig. 5. Brake force distribution characteristics of “CBS”.
Fig. 6. Application of CBS effect during ABS operation.
braking force increases, while the M.A.-C. ABS performs the CBS control also in the process where the braking force increases to secure the high braking performance during the ABS operation (Fig. 6).
3. Outline of test
There were three kinds of brake operation methods: operation of the right lever only, the left lever only and simultaneous operation of both levers, and the amount of deceleration was the maximum that each rider could control. The test was performed after the rider was sufficiently accustomed to riding the motorcycle, and the data for each operation method was collected five times. Moreover, after the running test, a questionnarie investigation about brake feeling was made. In the second test, the maximum deceleration was measured. This test was performed by an expert rider with high riding skill. The test motorcycle and the test method are similar to the first test.
3.1. Test motorcycle land measuring items Table 1 shows the major specifications of the test motorcycle. There are four measuring items: front wheel speed, rear wheel speed, right and left lever input force.
4. Test result
3.2. The test purpose and condition
Fig. 7 shows the test result as a comparison of deceleration. The lower maximum deceleration of the motorcycle with M.A.-C. ABS increased by 105% with single operation of the right lever, 11% with single operation of the left lever and 44% with the simultaneous operation of both levers compared to the motorcycle without M.A.-C ABS. Moreover, the maximum deceleration increased by 23% with the simultaneous operation of both levers for the beginners.
The first test was performed to confirm the brake feeling and ease of brake operation. 33 beginners with limited experience of riding motorcycles were selected as test riders. Two test motorcycles were used one with the M.A.-C. ABS installed and one without M.A.-C. ABS. The vehicle speed under test conditions was 40 km/h and the test road was a straight course with dry asphalt.
4.1. Brake feeling and ease of brake operation
T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377
377
Fig. 7. Comparison of beginners’s maximum deceleration. Fig. 8. Comparison of expert rider’s maximum deceleration.
For the motorcycle with M.A.-C ABS, the brake lever input force of the riders increased as their anxiety of a wheel lock might have decreased. In the questionnarie, the majority of respondents answered that the motorcycle with M.A.-C. ABS is easier to brake and gives a good brake feeling. There were some cases where the deceleration did not increase using the motorcycle with M.A.-C. ABS. There was a case where the input force did not increase to the point of ABS operation, a case where it was not able to brake effectively as the throttle was not fully closed. On the other hand, there was a case where the input force decreased after the ABS had operated. It is considered that as the motorcycle deceleration just before ABS operation is not much higher than the average deceleration until stopping, the braking input force was decreased by feeling the lever pulsation due to the ABS operation. 4.2. Maximum deceleration by an expert rider Fig. 8 shows the test result of the maximum deceleration by an expert rider. In the figure, M.A.-C. ABS (CBS) is the test result where the rider controlled the brake in a way not to use the ABS function to stop the motorcycle, M.A.-C. ABS (ABS) is the test result when the rider completely stopped the motorcycle with the ABS function activated. The maximum deceleration of the motorcycle without M.A.-C. ABS was 8.1 m/s2 with only right lever single operation, 4.2 m/s2 with only left operation and 8.3 m/s2 with simultaneous operation of both levers. The maximum deceleration of the motorcycle with M.A.-C. ABS when the ABS was not operated was 7.0 m/s2 only using the right lever, 6.2 m/s2 only using the left lever and 7.2 m/s2 using both levers simultaneously. The maximum deceleration of the motorcycle with M.A.-C. ABS when the ABS was operated was 7.0 m/s2
only using the right lever, 5.2 m/s2 only using the left lever and 6.9 m/s2 simultaneously using both levers. ABS is device to avoid wheel lock when an excessive input force is applied but not a device to increase the maximum deceleration. Nevertheless, the maximum deceleration of the M.A.-C. ABS equipped motorcycle only using the left lever increased more than 47% compared to a similar motorcycle without M.A.-C. ABS due to the CBS function. 5. Conclusion 1. The M.A.-C ABS was effective, for beginners particularly by improving their lower maximum deceleration and generally by increasing the maximum deceleration through the simultaneous operation of the front and rear brakes which is easily possible with this system. 2. The ABS and CBS of the M.A.-C. ABS released the riders from their anxiety of a wheel lock during braking and provided a brake system which is easy to operate with higher braking efficiency for beginners. 3. Operated by an expert rider, the M.A.-C. ABS increased the maximum deceleration using only the left lever by 47% due to the CBS function. References [1] Nishimoto, Y. et al., Research on combined brake system for motorcycle, International Motorcycle Conference: Safety-Environment-Future, Germany (1991). [2] Tsuchida, T. et al., Further research on combined brake system for motorcycle, 3rd SETC, Italy (1993). [3] Matsuto T. et al., Research of compact motor driven ABS, 28th ISATA, Germany (1995). [4] Kato M. et al., Combination of antilock brake system (ABS) and combined brake system CBS for motorcycle, SAE International Congress & Exposition, USA (1996).
New Technologies & New Cars
Development of motor actuated antilock brake system for light weight motorcycle Takeshi Wakabayashi!, Takushi Matsuto!, Kazhuiko Tani", Atsuo Ohta! ! Engineering Design Department, Honda R&D Co. Ltd., Asaka R&D Center, 3-15-1 Senzui Asaka, Saitama, 351-8555 Japan " Engineering Research Department, Honda R&D Co. Ltd., Asaka R&D Center, 3-15-1 Senzui Asaka, Saitama, 351-8555 Japan Received 6 April 1998
Abstract A brake system with the function of a Combined Brake System on the rear brake which distributes the controlled braking force to the front, and an Antilock Brake System on front and rear brakes was developed for the light weight motorcycle. Using a single channel actuator which consists of a reversible motor, an electromagnetic brake, a double planetary differential gear, etc., this brake system has achieved a low cost and small size, and was applied successfully to a 50 cc scooter. ( 1998 Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved.
1. Introduction
2. Outline of M.A.-C. ABS
The Motor Actuated Combined Antilock Brake System (hereinafter refered to as M.A.-C. ABS), as shown in Fig. 1, for light weight motorcycles was developed aiming to release riders from the anxiety of a wheel lock during braking and to provide an easy to operate brake system with higher braking efficiency. The first objective was achieved by adopting ABS, and the second was achieved by the Combined Brake System (hereinafter referred to as CBS). The CBS for motorcycles ensures optimum brake force distribution simultaneously to the front and rear wheels by operation of just one brake lever. The M.A.-C. ABS is a combination of ABS and CBS. This combination results in a simple, compact and inexpective system with a reduced number of parts which makes a light weight motorcycle possible. (For more information, see [1—4].) This M.A.-C. ABS was applied to the scooter “Live Dio ST” with 50 cc-engine displacement shown in Fig. 2, and put onto the Japanese market from 1996.
2.1. Composition of M.A.- C. ABS Fig. 3. shows the arrangement of the components of the M.A.-C. ABS. Fig. 4 shows a diagram of the actuator and the cable damper. The M.A.-C. ABS has a single actuator. The actuator makes the CBS and the ABS compatible by controlling rotation direction and force of a single motor. 1. Independently actuated brake systems for the front and rear wheels: A hydraulic disk brake is adopted for the front wheel and a cable type drum brake is adopted for the rear wheel. Primary brake cables are used between both levers and actuator. 2. Actuator: The actuator is arranged between the levers and the front and rear brakes. The actuato r is composed of a reversible motor, and electromagnetic brake, a double planetary differential gear, front and rear brake control arms, an angle sensor, etc.
0389-4304/98/$19.00 ( 1998 Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved. PII: S 0 3 8 9 - 4 3 0 4 ( 9 8 ) 0 0 0 3 4 - 4
JSAE9835393
374
T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377
Fig. 1. Motor actuated combined antilock brake system.
Fig. 3. Installation of M.A.-C. ABS.
Fig. 2. Live Dio ST.
3. Cable damper: The cable dampers are arranged on each of the primary brake cables which connect the levers and the actuator. The cable dampers are composed of a limit switch that operates when a certain cable tension is applied and springs to decrease the lever pulsation when the ABS operates. 4. ECU: The ECU consists of an 8 bit-CPU which controls the CBS and ABS and a motor drive circuit, and performs self diagnosis in addition to diagnosing the
entire system. The indicator lamp flashes when the ECU detects any abnormality of the system. 2.2. Operation principle of the M.A.-C ABS The CBS operates only when an input force is given to the left lever. The actuator generates the front wheel braking force according to the input force. Fig. 5 shows the relation of the distribution between front and rear wheel braking force. The left lever input is transmitted to the rear drum brake by the cable damper and the rear brake control
T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377
375
Fig. 4. Actuator and cable damper.
arm. After the limit switch of the cable damper operates, the angle sensor of the actuator detects the operation angle of the rear brake control arm as a stroke of the left lever operation. The wheel speed sensors detect the rotation pulse of the front and rear wheels. These signals are transmitted to the ECU. To operate the actuator, the ECU sends the current to the electromagnetic brake of the actuator and the motor at the same time. The amount of motor current is calculated by the ECU based on the operation of the left lever input condition, the play of rear brake cable, the vehicle speed, etc. The motor rotates the front brake control arm according to the current value and generates the front braking force. During ABS operation, the motor of the actuator rotates in the opposite direction to that during CBS operation. The motor torque is transmitted in the direction where front and rear braking force is reduced and it controls the front and rear braking force at the time at a predetermined rate. The ECU calculates the slip ration and the deceleration of the front and rear wheels based on the signal sent from each wheel speed sensor. The ECU sends the signals of current of the electromagnetic brake to the actuator and the current necessary to avoid wheel locking to the motor. At this time, the internal springs of the cable dampers contract when the tension of the brake cable becomes above a certain value, and decrease the lever pulsation. When the ECU detects the recovery of the front and rear wheels slip ratio, it decreases the motor torque and increases the braking force again. Repeating the above operation, the actuator controls the braking force until the motorcycle almost stops or the input force is released.
2.3. Control of M.A.-C. ABS The maximum deceleration on each type of road surface condition is generated based on the ideal braking force distribution curve shown in Fig. 5. However, the CBS characteristic of M.A.-C. ABS is set increasing the rear braking force compared with the ideal distribution curve. This is a setting to assure locking of the rear wheel first, when there is an excessive input from the left lever to the rear brake. When the left lever is operated, the limit switch of the cable damper operates at point A shown in Fig. 5 and the actuator starts to generate additional front braking force. The amount of front braking force to be added is controlled responding to the state of lever operation by the rider, the vehicle speed, etc. The ABS of M.A.-C. ABS is a single channel control system. In this single channel control, when either the front wheel or rear wheel is locked, both brakes are operated by the ABS at the same time. The rear wheel slip ratio is determined by the calculation result of the ECU. The operation point of the ABS on the rear wheel is decided by the ECU judging if the road surface is slippery or not according to the relation between the differentiation value of the rear wheel slip ratio and the input force. Therefore the braking performance and the motorcycle control for various road surface conditions are assured. Moreover, the M.A.-C. ABS has a dead zone where neither the ABS nor the CBS operate, so that the brake operation changes smoothly when the control changes from the ABS to the CBS. The ABS operation repeats the process where the braking force decreases and the process where the
376
T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377 Table 1 Specification of test motorcycle Items
Motorcycle A Motorcycle B
Brake system
M.A.-C. ABS
Wheel base : ¸ (m) Curb mass : M (kg) Height of C.G. : H (m) Distance between C.G. and rear axle : X (m) Distributed load of motorcycle wilth one rider, front/rear (N)
1.148 79.7 0.622
Conventional brake 1.148 74.5 0.612
0.714
0.716
525/822
464/831
Fig. 5. Brake force distribution characteristics of “CBS”.
Fig. 6. Application of CBS effect during ABS operation.
braking force increases, while the M.A.-C. ABS performs the CBS control also in the process where the braking force increases to secure the high braking performance during the ABS operation (Fig. 6).
3. Outline of test
There were three kinds of brake operation methods: operation of the right lever only, the left lever only and simultaneous operation of both levers, and the amount of deceleration was the maximum that each rider could control. The test was performed after the rider was sufficiently accustomed to riding the motorcycle, and the data for each operation method was collected five times. Moreover, after the running test, a questionnarie investigation about brake feeling was made. In the second test, the maximum deceleration was measured. This test was performed by an expert rider with high riding skill. The test motorcycle and the test method are similar to the first test.
3.1. Test motorcycle land measuring items Table 1 shows the major specifications of the test motorcycle. There are four measuring items: front wheel speed, rear wheel speed, right and left lever input force.
4. Test result
3.2. The test purpose and condition
Fig. 7 shows the test result as a comparison of deceleration. The lower maximum deceleration of the motorcycle with M.A.-C. ABS increased by 105% with single operation of the right lever, 11% with single operation of the left lever and 44% with the simultaneous operation of both levers compared to the motorcycle without M.A.-C ABS. Moreover, the maximum deceleration increased by 23% with the simultaneous operation of both levers for the beginners.
The first test was performed to confirm the brake feeling and ease of brake operation. 33 beginners with limited experience of riding motorcycles were selected as test riders. Two test motorcycles were used one with the M.A.-C. ABS installed and one without M.A.-C. ABS. The vehicle speed under test conditions was 40 km/h and the test road was a straight course with dry asphalt.
4.1. Brake feeling and ease of brake operation
T. Wakabayashi et al. / JSAE Review 19 (1998) 373—377
377
Fig. 7. Comparison of beginners’s maximum deceleration. Fig. 8. Comparison of expert rider’s maximum deceleration.
For the motorcycle with M.A.-C ABS, the brake lever input force of the riders increased as their anxiety of a wheel lock might have decreased. In the questionnarie, the majority of respondents answered that the motorcycle with M.A.-C. ABS is easier to brake and gives a good brake feeling. There were some cases where the deceleration did not increase using the motorcycle with M.A.-C. ABS. There was a case where the input force did not increase to the point of ABS operation, a case where it was not able to brake effectively as the throttle was not fully closed. On the other hand, there was a case where the input force decreased after the ABS had operated. It is considered that as the motorcycle deceleration just before ABS operation is not much higher than the average deceleration until stopping, the braking input force was decreased by feeling the lever pulsation due to the ABS operation. 4.2. Maximum deceleration by an expert rider Fig. 8 shows the test result of the maximum deceleration by an expert rider. In the figure, M.A.-C. ABS (CBS) is the test result where the rider controlled the brake in a way not to use the ABS function to stop the motorcycle, M.A.-C. ABS (ABS) is the test result when the rider completely stopped the motorcycle with the ABS function activated. The maximum deceleration of the motorcycle without M.A.-C. ABS was 8.1 m/s2 with only right lever single operation, 4.2 m/s2 with only left operation and 8.3 m/s2 with simultaneous operation of both levers. The maximum deceleration of the motorcycle with M.A.-C. ABS when the ABS was not operated was 7.0 m/s2 only using the right lever, 6.2 m/s2 only using the left lever and 7.2 m/s2 using both levers simultaneously. The maximum deceleration of the motorcycle with M.A.-C. ABS when the ABS was operated was 7.0 m/s2
only using the right lever, 5.2 m/s2 only using the left lever and 6.9 m/s2 simultaneously using both levers. ABS is device to avoid wheel lock when an excessive input force is applied but not a device to increase the maximum deceleration. Nevertheless, the maximum deceleration of the M.A.-C. ABS equipped motorcycle only using the left lever increased more than 47% compared to a similar motorcycle without M.A.-C. ABS due to the CBS function. 5. Conclusion 1. The M.A.-C ABS was effective, for beginners particularly by improving their lower maximum deceleration and generally by increasing the maximum deceleration through the simultaneous operation of the front and rear brakes which is easily possible with this system. 2. The ABS and CBS of the M.A.-C. ABS released the riders from their anxiety of a wheel lock during braking and provided a brake system which is easy to operate with higher braking efficiency for beginners. 3. Operated by an expert rider, the M.A.-C. ABS increased the maximum deceleration using only the left lever by 47% due to the CBS function. References [1] Nishimoto, Y. et al., Research on combined brake system for motorcycle, International Motorcycle Conference: Safety-Environment-Future, Germany (1991). [2] Tsuchida, T. et al., Further research on combined brake system for motorcycle, 3rd SETC, Italy (1993). [3] Matsuto T. et al., Research of compact motor driven ABS, 28th ISATA, Germany (1995). [4] Kato M. et al., Combination of antilock brake system (ABS) and combined brake system CBS for motorcycle, SAE International Congress & Exposition, USA (1996).